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3-21.38 | 29 | Plans, Organization, Conduct, and Threat
Figure 2-2. Comparison of air routes with and without a high-threat environment. |
3-21.38 | 31 | THIS CHAPTER IMPLEMENTS STANAGs 2863 and 3281.
Chapter 3
Air Traffic Control
This chapter discusses the pathfinder air traffic controller, not the regular air traffic
controller. The latter has radar and other sophisticated tools to monitor weather and
guide aircraft. The pathfinder has only his training, so he can only advise and inform
the pilot. Based on what the pathfinder tells him and on his own observations, the
pilot must then decide whether to land, take off, or drop equipment or personnel.
Unless clearly stated otherwise, “air traffic controller” refers to the pathfinder air
traffic controller. This chapter also includes other terms peculiar to air traffic control
(ATC) tasks.
SECTION I. PATHFINDER AIR TRAFFIC
The pathfinder air traffic controller uses radio or directional light signals to provide flight information, expedite
traffic, and prevent collisions.
SAFETY
.
3-1. Pathfinders issue specific commands regulating vehicles, equipment, or personnel in the
movement area. They help with search-and-rescue operations (STANAGs 2863 and 3281). They also
promote the safe, efficient flow of air traffic by issuing clearances, instructions, and information.
3-2. Pathfinders survey all visible air traffic operating within and around the airspace of the LZ, DZ, or
airfield. They also bear the responsibility for all aircraft, vehicles, and personnel in the movement area of
the LZ, DZ, or airfield.
3-3. Pathfinders acting as air traffic controllers provide control service by observing or knowing of
traffic and airfield conditions that might constitute a hazard. These include—
y Surface conditions.
y Parachutists within control zones.
y Vehicular traffic.
y Temporary obstructions on or near the LZ, DZ, or airfield.
y Other aircraft.
y Enemy or friendly activities.
3-4. Because of their communication capability and expertise, pathfinders might have to transmit
medical evacuation (MEDEVAC) requests for the ground unit, the aviation unit, or even themselves.
Therefore, they must be thoroughly familiar with request procedures and the capabilities of MEDEVAC
aircraft.
VOICE CONTROL
3-5. To communicate vocally, pathfinders and pilots must speak clearly and listen to each other.
A clear, decisive tone of voice indicates control of the situation. Pilots might mistrust instructions delivered |
3-21.38 | 32 | Chapter 3
in a vague or hesitant voice. To ensure that traffic flows safely and smoothly, the pathfinder must speak
firmly and confidently, using standard words and phrases. Pathfinders use the phonetic alphabet to indicate
single letters or initials, or to spell words, whenever similar sounds or difficulties in communication require
them to do so.
3-6. Voice transmission offers a brief, concise, uniform flow of communication. The pathfinder
controller must speak distinctly and pay special attention to numbers. When the accuracy of a message is
doubtful, he repeats the complete message or essential parts. Radio operators use the following techniques
to ensure clear understanding:
y Speak directly into the microphone.
y Speak in a normal, conversational tone.
y Vary your pitch—avoid speaking in a monotone.
y Speak at a comfortable speed—avoid speaking too slow or too fast.
y Keep your tone clear, professional, and firm. Avoid showing fear, indecision, anger, or other
negative emotions in your tone of voice.
y Speak with confidence, especially in emergencies.
3-7. The pathfinder ATC must transmit messages only as necessary for control or to help ensure safety.
Specific procedures and control techniques vary, but the following rules apply regardless of the
techniques used:
y The pathfinder issues instructions and information about all known traffic conditions.
y The pilot uses at lease one component of a standard traffic pattern (final approach), consistent
with the pathfinder's instructions.
y The pilot has the final authority about whether to accept clearances issued by a controller.
FORMATS
3-8. A pathfinder controller uses the following formats and sequences for ground-to-air radio
communication:
y To initially call up an aircraft, he--
– Identifies the aircraft he wishes to call.
– Says, "THIS IS."
– Identifies the calling unit.
– Identifies the type of message to follow (when this will help the pilot).
– Says, "OVER."
Example: TANGO TWO SIERRA TWO SIX (T2S26), THIS IS CHARLIE THREE
DELTA THREE SIX (C3D36) (short pause), OVER.
y To reply to an aircraft's initial call-up, he--
– Identifies the aircraft initiating the call-up.
– Says, "THIS IS."
– Identifies the pathfinder control unit.
– Says, "OVER." After establishing communications with an aircraft, shortens the
transmission by using only the last three numbers (or letters) of each party's (his and the
aircraft's) identification.
Example: SIERRA TWO SIX, THIS IS DELTA THREE SIX, OVER. |
3-21.38 | 33 | Air Traffic Control
3-9. The controller always starts a clearance (instruction) intended for a specific aircraft by identifying
that aircraft. If he thinks that using the shortened identification could cause or is causing confusion, he can
go back to using the full identification.
Example: SIERRA TWO SIX, WIND CALM, CLEAR TO LAND, OVER.
3-10. The controller can omit "THIS IS" from the reply.
Example: SIERRA TWO SIX, DELTA THREE SIX, OVER.
3-11. The controller can omit the facility identification.
Example: SIERRA TWO SIX, TURN TO HEADING ZERO FOUR FIVE, OVER.
3-12. Right after call-up, without waiting for the aircraft to reply, the controller can send a short
message that he expects the aircraft to receive.
Example: SIERRA TWO SIX, EXTEND DOWNWIND, OVER.
3-13. If the message obviously requires a reply, he can omit "OVER."
Example: SIERRA TWO SIX, WHAT IS YOUR LOCATION?
3-14. To distinguish between similar aircraft identifications, he might emphasize appropriate numbers,
letters, or words. The controller never transmits to an aircraft during the final approach, touchdown,
landing roll (touchdown), takeoff (liftoff), initial climb, or turnaway from the field. At these times, the pilot
must concentrate on flying the aircraft. However, he transmits at once any condition or information that
could affect the safety of the aircraft. Under no circumstances does the controller withhold from the pilot of
an approaching aircraft any information about hazardous runways, fields, weather, or traffic conditions.
NUMBERS
3-15. A pathfinder controller transmits numbers by units or digits (Table 3-1).
To Transmit Say
CEILING HEIGHTS "CEILING FIVE HUNDRED" (one unit) or "CEILING FIVE-ZERO-ZERO" (digits for emphasis).
and FLIGHT
"ALTITUDE ONE THOUSAND THREE HUNDRED" (two units) or "ALTITUDE
ALTITUDES
ONE-THREE-ZERO-ZERO" (in digits).
TIME Use the word TIME followed by the number. For example, "0115 HOURS TIME,
ZERO-ONE-ONE-FIVE" or "1315 HOURS TIME, ONE-THREE-ONE-FIVE."
ELEVATION Use the words FIELD ELEVATION and the number. For example, for a 17-foot elevation, say,
NUMBERS "FIELD ELEVATION SEVENTEEN." For a 50-foot elevation, say, "FIELD ELEVATION FIFTY."
WIND SPEED Use the word WIND followed by compass direction and velocity (knots). For example, "WIND
TWO-SEVEN-ZERO AT FIVE."
HEADING Use the word HEADING followed by compass numbers (degrees); omit the word DEGREES.
For example, "HEADING ONE TWO ZERO," "HEADING ZERO-ZERO-FIVE," or "HEADING
THREE-SIX-ZERO." (The latter indicates a North [direction] heading.)
Table 3-1. Numbers transmitted by units or digits. |
3-21.38 | 34 | Chapter 3
PHRASES AND TERMS
3-16. A pathfinder controller uses particular phrases (Table 3-2) and terms (Table 3-3) to control and
communicate with aircraft. He must know these phrases and how to use them.
Intent Example
Issue takeoff, liftoff, or departure SIERRA TWO SIX, CLEARED FOR IMMEDIATE TAKEOFF (or
clearance when delay is undesirable. DEPARTURE), OVER.
Issue takeoff (liftoff) clearance when SIERRA TWO SIX, TAKE OFF (or DEPART) IMMEDIATELY OR
aircraft is delaying on the runway. TAXI OFF THE RUNWAY, OVER.
Authorize a requested straight-in SIERRA TWO SIX, STRAIGHT-IN APPROACH (to landing strip
approach after issuing landing or LZ) APPROVED, OVER.
instructions.
Authorize a right-hand traffic pattern. SIERRA TWO SIX, RIGHT TRAFFIC APPROVED, OVER.
Issue the landing sequence. SIERRA TWO SIX, YOU ARE NUMBER THREE TO LAND;
FOLLOW THREE EIGHT FIVE (aircraft identification number) ON
DOWNWIND, OVER.
Instruct pilot to extend downwind leg SIERRA TWO SIX, EXTEND DOWNWIND FOR TRAFFIC
to obtain necessary aircraft SPACING, OVER.
separation.
Advise pilot of information not SIERRA TWO SIX, BE ADVISED WE ARE RECEIVING
included in landing instructions, but AUTOMATIC FIRE FROM THE EAST, OVER.
important to aircraft safety.
Try to establish communication with UNIFORM HOTEL ONE, TWO MILES WEST OF BLUE STRIP,
and learn the identification of an STATE CALL SIGN, OVER.
aircraft in the area.
Instruct pilot to circle the LZ or SIERRA TWO SIX, MAINTAIN LEFT (RIGHT) CLOSED
landing strip. TRAFFIC, OVER.
Issue clearance to land. SIERRA TWO SIX, CLEAR TO LAND, OVER.
Instruct a pilot on his final landing SIERRA TWO SIX, CONDUCT GO-AROUND, OVER.
approach that his clearance to land
has been cancelled.
Inform pilot to continue his approach SIERRA TWO SIX, CONTINUE APPROACH, OVER.
to the landing area.
Inform pilot of observed aircraft SIERRA TWO SIX, LANDING GEAR APPEARS DOWN AND IN
condition upon request or when PLACE, OVER.
necessary.
Describe vehicles, equipment, or SIERRA TWO SIX, AIRCRAFT TO LEFT OF RUNWAY, OVER.
personnel in the movement area in a SIERRA TWO SIX, VEHICLES ON TAXIWAY, OVER.
way that will help pilots see or
recognize them.
Describe military traffic as SIERRA TWO SIX, BE ADVISED HELICOPTER ON
appropriate. DEPARTURE END, OVER. SIERRA TWO SIX, BE ADVISED,
CHARLIE HOTEL FOUR SEVEN (CH-47) ON RIGHT SIDE OF
RUNWAY, OVER.
Describe the relative positions of SIERRA TWO SIX, UNIFORM SIX, YOUR THREE O'CLOCK,
traffic using the clock FIVE HUNDRED METERS, OVER.
direction-and-distance method.
Table 3-2. Phrases. |
3-21.38 | 35 | Air Traffic Control
Term Meaning
ABORT Do not complete landing or takeoff (liftoff).
ACKNOWLEDGE Did you receive and understand the message?
AFFIRMATIVE Yes.
BE ADVISED Indicates additional information is forthcoming, such as an unusual condition
or hazard to flight.
BREAK That is the end of my transmission to you. The following message is for
another aircraft. OR, that is the end of this part of the message. The next
portion follows.
CONDUCT GO-AROUND Do not land. Circle the landing area, and begin another approach.
CORRECTION I gave you some incorrect information. The correct information follows.
EXECUTE Drop personnel or equipment.
FORM YOUR OWN You might enter the traffic pattern at your discretion. (Most suitable for
APPROACH. aircraft with a slingload or for aircraft flights.)
GO AHEAD Proceed with your message.
I SAY AGAIN I am about to repeat my previous message.
LAST CALLING I do not know the identity of the station trying to establish communication.
STATION
MAYDAY This is an emergency—clear the airways.
NEGATIVE No.
NO DROP Do not drop personnel or equipment.
OUT That is the end of my transmission; you need not respond.
OVER That is the end of my transmission; please respond.
READ BACK Repeat message.
REPORT Contact the control facility when you reach the location (or distance from the
control station) that I am about to designate.
ROGER I received and understand your transmission.
SAY AGAIN Repeat your message.
STAND BY Pause for a few seconds. OR, prepare to drop personnel or equipment.
STATE CALL SIGN Identify your aircraft.
STATE INTENTIONS Tell me your plans.
STATE LOCATION Tell me your exact location.
UNABLE TO APPROVE I must refuse your request.
VERIFY Check with the originator.
WILCO I understand and will comply.
WORDS TWICE Communication is difficult; transmit each phrase twice.
YOU ARE I do not understand the transmission.
UNREADABLE
(BROKEN OR
GARBLED)
Table 3-3. Terms. |
3-21.38 | 36 | Chapter 3
SECTION II. LANDINGS
The safe landing of aircraft requires control of the airspace and grounds around the site. Managing air traffic
involves using traffic patterns and maintaining separation of aircraft.
TRAFFIC PATTERNS
3-17. The pathfinder uses a traffic pattern to help manage airspace over his location, that is, in and
around a landing site, airfield, LZ, or DZ (Figure 3-1). A traffic pattern normally extends out 1 statute mile
from the final approach of the landing area in all directions, depending on the type of aircraft or size of
the facility.
3-18. In a normal (left) traffic pattern, the aircraft makes only left turns. The pilot keeps the airfield,
landing site, LZ, or DZ to his left. In a right traffic pattern, the aircraft makes all right turns. The pilot
keeps everything to his right.
3-19. The controller uses traffic patterns to manage aircraft separation around a no-threat landing site.
Rotary-wing aircraft can enter the pattern from any direction as long as they meet safety requirements. The
height of the obstacles or aircraft requirements determines the altitude, which the controller can adjust
as needed.
3-20. While in the traffic pattern, the aircraft flies between 1,000 and 1,200 feet (known as civil
altitude), though this might vary depending on the nature and requirements of the mission.
METHODS OF ENTRY
3-21. An aircraft might enter the traffic pattern from any point and direction within the area around the
landing strip or zone, consistent with safety requirements.
3-22. Fixed wing aircraft normally enter the traffic pattern in the first one-third of the closest leg, at a
45-degree angle or less. Rotary wing aircraft might enter at any point in a leg, normally at a 45-degree
angle or less.
3-23. A straight-in approach might work best if it falls within safety requirements. On a straight-in
approach, the aircraft must remain within 30 degrees to either side of the land heading.
3-24. When circling to approach from any direction, the aircraft overflies the landing site then circles to
the direction of landing. Normally, the pathfinder advises the pilot which direction to circle. This saves
time and helps the aircraft avoid other traffic in the same airspace. The pathfinder most often encounters
this type approach.
3-25. Departing aircraft normally leave on the same heading as landing aircraft, or as close to the same
heading as they can, up to 45 degrees left or right of the land heading, depending on the wind direction.
When the destination does not fall in the same direction as the departure, the aircraft might fly a portion of
the traffic pattern. The pathfinder ensures that arriving and departing traffic do not conflict.
3-26. The controller commands GO-AROUND if for some reason the aircraft does not land after the
pilot reaches the final approach leg of the traffic pattern.
3-27. The pathfinder uses closed traffic in either of two cases:
y When an aircraft fails to land on the first approach.
y During DZ operations, when an aircraft must make more than one pass over the DZ. |
3-21.38 | 37 | Air Traffic Control
Figure 3-1. Air traffic patterns. |
3-21.38 | 38 | Chapter 3
TRAFFIC PATTERN LEGS
3-28. The traffic pattern has five possible legs. The pathfinder does not use them all at once. The pilot
must at least fly the final approach leg, regardless of the type of approach (Table 3-4).
Leg Flight Course Direction
UPWIND Parallel to land heading Landing direction
CROSSWIND Right angle to land heading Landing direction
DOWNWIND Parallel to land heading Direction opposite of landing direction
BASE Right angle to landing runway Extends from downwind leg to intersection of
runway centerline (extended)
FINAL Along runway centerline Landing direction; extends from base leg down
(APPROACH) to the runway
Table 3-4. Traffic pattern legs.
ADVISORY SERVICE
3-29. The pathfinder controller issues advisories for the safe operation of aircraft in his area of
responsibility. He might include such information as the temporary or permanent conditions on the
landing field.
3-30. Temporary conditions can include—
y Construction work on or immediately next to the movement area.
y Rough portions of the movement area.
y Degraded runway braking conditions due to ice, snow, mud, slush, or water.
y Parked aircraft on the movement area.
3-31. Permanent conditions can include—
y Excessive slope.
y Obstacles 18 inches high, wide, or deep on the HLZ.
y Elevation.
3-32. No two landing areas and situations are the same. Each location presents its own problems with
respect to environmental conditions, peculiar weather, preferred landing directions, and so forth.
For example—
y The final approach to a particular runway or HLZ might require a higher-than-normal glide
slope angle.
y Under certain wind conditions, unusual terrain features near the airfield or HLZ can cause
turbulence. This could threaten nearby aircraft. Helicopters also can create turbulence that
could result in harm to light aircraft.
y Prohibited areas, trees, mountains, or other obstacles and hazards directly in line with the end
of the runway or around the HLZ can require the pilot to turn or maneuver the aircraft abruptly
right after takeoff (liftoff).
y If friendly forces fire either artillery or mortars within the control zone, the pathfinder might
need to tell the pilot the origin, range, direction, and maximum ordinate of the firing. He also
tells the pilot about any air strikes in the control zone, especially those by high-performance
aircraft. He also gives the pilot any available information about the enemy situation. |
3-21.38 | 39 | Air Traffic Control
SPACING TECHNIQUES
3-33. Spacing provides more separation between aircraft in the traffic pattern. This relieves traffic
congestion. The pathfinder controller uses two methods to obtain the required separation: the 360-degree
turnout and the traffic pattern extension.
360-DEGREE TURNOUT
3-34. Except on the final approach, the pathfinder can issue instructions for the 360-degree turnout (a
two-minute maneuver) at any point in the traffic pattern. When a pilot receives instructions to begin a
360-degree turnout, he turns away from the center of the landing site, makes a wide circle, and reenters the
traffic pattern at about the same point where he left it (Figure 3-2 and Table 3-5). If the first turnout does
not give him enough room, he might have to make more turnouts.
Pathfinder: DELTA THREE SIX, BEGIN THREE SIX ZERO DEGREE TURNOUT
FOR SPACING, AND REPORT REENTRY.
Pilot: ROGER. (After completing turnout) LIMA ONE SIX, DELTA THREE SIX
HAS REENTERED.
Pathfinder: DELTA THREE SIX, ROGER, REPORT BASE.
Pilot: ROGER.
Figure 3-2. 360-degree turnout.
Situation Reporting Point
AIRCRAFT IN TRAFFIC BASE LEG OF TRAFFIC
PATTERN
STRAIGHT-IN APPROACH FINAL
AIRCRAFT AUTHORIZED TO FINAL
FORM OWN APPROACH
Table 3-5. A 360-degree turnout. |
3-21.38 | 40 | Chapter 3
THREE LEGS OF TRAFFIC PATTERN
3-35. The pathfinder can only extend the traffic pattern on three legs: upwind, crosswind, and
downwind (Figure 3-3). He can only extend one leg at a time. He cannot extend the base leg or the final
approach, because they run back into the traffic pattern itself. When giving instructions to extend the traffic
pattern, the pathfinder includes the length of the extension. The extension normally measures twice the
original length of that leg (1 statute mile). The pathfinder takes care to ensure that he does not extend the
leg so far that he loses visual contact with the aircraft.
Figure 3-3. Traffic pattern extension.
FINAL LANDING INSTRUCTIONS
3-36. Final landing instructions consist of a current wind reading (direction and velocity) and clearance
to land. The pathfinder includes any change to the situation in the final landing instructions, which he
issues as soon as the pilot reports from the designated point. As a rule, once the pathfinder clears an aircraft
to land, he can only rescind that clearance in extreme situations.
3-37. The best reporting points vary with the situation.
3-38. Aircraft flying in formation, except those flying in trail, and aircraft with a slingload, usually form
their own approach.
3-39. If two or more missions arrive at the same time, the controller gives first landing priority to
in-flight emergencies, followed by MEDEVAC aircraft. His next priority is coded aircraft, multiple aircraft
in formation, and aircraft with slingloads. His last priority is single aircraft.
TAXIING AIRCRAFT
3-40. When issuing taxiing instructions, the pathfinder includes a route for the aircraft to follow in the
movement area. He also includes instructions for the pilot to hold the aircraft at a specific point, if needed.
The pilot moves the aircraft in the loading, maintenance, dispersal, or parking areas without the
pathfinder's help but sometimes aided by signalmen. The controller holds a taxiing aircraft short of an
active runway by at least two airplane lengths. This ensures that landing aircraft have sufficient clearance.
The controller issues concise, easy-to-understand information.
Example: SIERRA TWO SIX, TURN RIGHT AT SIGNALMAN.
TANGO THREE SIX, TURN LEFT AT END OF RUNWAY, OVER. |
3-21.38 | 41 | Air Traffic Control
MINIMUM AIRCRAFT SEPARATION REQUIREMENTS
3-41. During normal operations, pathfinders ensure pilots follow minimum separation criteria. Combat
situations might dictate less separation (Figure 3-4).
ARRIVING AIRCRAFT
3-42. The preceding aircraft (1) taxis off the landing strip before the arriving aircraft (2) crosses the
approach end on its final glide (A, Figure 3-4).
DEPARTING AIRCRAFT
3-43. The preceding aircraft either crosses (1) the opposite end of the runway or turns away from the
projected path of the departing aircraft (2) before the latter begins its takeoff run (B, Figure 3-4).
DEPARTING AND ARRIVING AIRCRAFT
3-44. The departing aircraft (1) crosses the opposite end of the runway before the arriving aircraft (2)
crosses the approach end on its final glide path (C, Figure 3-4).
DEPARTING, PRECEDING, AND ARRIVING AIRCRAFT
3-45. The preceding aircraft (1) and the arriving aircraft (2) both taxi off the runway before the
departing aircraft (3) begins the takeoff run (D, Figure 3-4).
Figure 3-4. Minimum separation requirements. |
3-21.38 | 42 | Chapter 3
DANGER
Arriving and departing aircraft with slingloaded cargo must never
fly over personnel, equipment, or other aircraft.
SECTION III. GROUND-TO-AIR COMMUNICATIONS
Air traffic control requires a rapid and efficient means of communication between aircraft and ground stations.
Two-way radio offers the most efficient means because it allows clear and rapid exchange of information. Not
all aircraft have radios that work. A system of visual signals serves as a backup or standby means of
communication when the control center or aircraft radio does not work, or if the aircraft does not have the
control frequency (Table 3-6). Pathfinders might also use colored smoke signals but must coordinate with the
aviation unit so that the pilots will know what each color means.
ELECTRONIC WARFARE ENVIRONMENT
3-46. The pathfinder should expect an active EW environment for all operations. He should make sure
he knows the proper ECCM. These include prowords that signal a switch to an alternate radio frequency,
transmission authentication procedures, brevity codes, and required reports when he suspects enemy
interference. The pathfinder uses proper communications procedures and signal operating instructions
(SOI) during all operations.
3-47. To limit the possibility of compromise, the pathfinder reduces the electronic signature at the LZ or
DZ. For this, he depends on thorough mission planning and coordination. He plans control procedures that
enable him to execute the mission under radio listening silence. All pathfinder missions seek to achieve
this goal.
3-48. Sometimes, the pathfinder has little time to plan the mission. At other times, tactical or
meteorological conditions can affect the operation. In either case, the pathfinder might have to use GTA
communications to resolve possible conflicts between friendly airspace users and to advise them of
previously-unknown restrictive landing conditions. These conditions could include wind gusts, hazardous
slopes, obstacles, soft landing surfaces, or a limited number of landing points. Training and close liaison
with aviation aircrews enable the pathfinder to develop an understanding of what information pertains to
the situation. This reduces transmission time.
3-49. The pathfinder manages any variation due to unknown influences just as he would manage any
other exception to set procedure. The landing site is the variable most subject to change. Many conditions
could require its relocation. For example, ground fog could cause a delay while the pathfinders move the
site to a higher elevation.
3-50. Before they know whether a site will support sufficient landing points or an assembly area for the
ground unit, the pathfinders must first secure the site, and then conduct air and ground reconnaissance and
surveillance.
3-51. If the mission is to reinforce or resupply a ground unit in contact, a change in the tactical situation
could render the proposed location unsuitable. If the pathfinders locate the proposed site near enemy
activity, they will most likely have to move it sometime between planning and execution to ensure that it
continues to meet mission requirements.
3-52. Maintaining radio silence within the LZ is important. Because of this, most air movements require
the establishment of a CCP. This ensures a common point where the pathfinders and the aircraft can refer
their relative positions and give each other time to adjust to other changes.
3-53. The GTA net is reserved for communications, but the pathfinder cannot assume that all
transmissions originate from aircraft. The headquarters in charge of flight plans logs all arrivals. They will |
3-21.38 | 43 | Air Traffic Control
know if an aircraft fails to arrive at its destination on time. When this happens, they contact intermediate
stop points to identify the last known location, and to aid in search-and-rescue operations.
Color And Type What This Means to an What This Means to an
of Signal Lights Aircraft on the Ground Aircraft in Flight
Steady green Cleared for takeoff (or liftoff) Cleared to land
Flashing green Cleared to taxi Return for landing (followed
by a steady green light at the
proper time)
Steady red Stop Give way to other aircraft
and continue circling
Flashing red Taxi clear of landing area of Airport unsafe—do not land
runway in use
Flashing white Return to starting point (on NA
airfield)
Alternating red and green Use extreme caution Use extreme caution
(general warning signal)
Red pyrotechnic NA Do not land for the time
(red flare) being, despite previous
instructions.
Table 3-6. Light signals on or near a landing zone.
GROUND-TO-AIR TRANSMISSIONS
3-54. The pathfinder might encounter endless situations while using GTA. If he can master the
following four most common ones, he can handle most situations:
SITUATION 1, KNOWN AIRCRAFT LOCATION
3-55. Known aircraft location is the simplest of the GTA transmissions. |
3-21.38 | 44 | Chapter 3
Initial Contact
3-56. The pilot radios transmissions at coordinated time and location. After establishing two-way
communications, the controller can abbreviate call signs. With multiple flights, instructions issued by
pathfinder GTA communications should identify the particular situation by including that station's call sign
at the beginning of the transmission, for example--
Pilot: ALPHA ONE LIMA ONE SIX (A1L16), THIS IS ROMEO TWO BRAVO
TWO SEVEN (R2B27), OVER.
Pathfinder: ROMEO TWO BRAVO TWO SEVEN, THIS IS ALPHA ONE LIMA ONE
SIX, OVER.
Pilot: THIS IS BRAVO TWO SEVEN, CCP INBOUND, OVER.
Pathfinder: THIS IS LIMA ONE SIX, STATE TYPE, NUMBER, AND INTENTIONS,
OVER.
Pilot: THIS IS BRAVO TWO SEVEN, FOUR UNIFORM HOTEL SIXTIES
(UH-60s), TROOP DROP-OFF AND SLINGLOAD, FOR YOUR SITE,
OVER.
Pathfinder: THIS IS LIMA ONE SIX, ROGER, HEADING THREE-TWO-FIVE (325),
THREE THOUSAND (3,000) METERS. LAND THREE TWO FIVE,
SIGNAL ON CALL, LAND ECHELON RIGHT, SLINGLOAD AIRCRAFT
USE NUMBER FOUR LANDING POINT, CONTINUE APPROACH FOR
VISUAL CONTACT, OVER.
Air Traffic Control Information
3-57. An example of what the air traffic controller might say follows:
Example: HEADING THREE TWO FIVE, (distance) THREE THOUSAND
METERS, OVER. LAND THREE TWO FIVE, OVER.
Pertinent Information
3-58. The air traffic controller also gives any other pertinent information, for example--
Example: SIGNAL ON CALL (prepare to establish positive visual contact).
FOUR UNIFORM HOTEL SIXTIES (UH-60s) IN ECHELON RIGHT
(advises pilot of the size of landing site).
SLINGLOAD POINT ON NUMBER FOUR TOUCHDOWN POINT
(night only).
FIELD ELEVATION, FOUR TWO FIVE FEET (actual field elevation). |
3-21.38 | 45 | Air Traffic Control
Advisory Information
3-59. See Table 3-7.
Type of Advisory Information Included
FLIGHT The enemy situation, if it presents a threat to the aircraft.
LANDING Surface conditions on the landing site such as the presence of
sand, mud, or blowing snow.
DEPARTURE Obstacles in the path of aircraft leaving the site (obstacles above
the obstacle departure lights).
Table 3-7. Information included in advisories.
Aircraft in Sight
3-60. The following shows what the pilot and pathfinder say when an aircraft is in sight of the runway:
Pathfinder: BRAVO TWO SEVEN, THIS IS LIMA ONE SIX, I AM AT YOUR
TWELVE O'CLOCK, FIVE HUNDRED METERS, IDENTIFY SIGNAL,
OVER.
Pilot: THIS IS BRAVO TWO SEVEN, I IDENTIFY GREEN SMOKE, OVER.
3-61. At night, during specialized activities such as external load drop-off or pickup, or when unsafe
surface conditions require pathfinders to mark specific landing points, the flight leader must know all
arrangements. This allows him to organize the flight for landing. Pathfinders identify the site by flashing a
visible or infrared light source in a dot-dash sequence.
Pathfinder: THIS IS LIMA ONE SIX, VISUAL CONTACT (and, once the pilot
identifies the site), WIND THREE TWO FIVE AT EIGHT, CLEAR TO
LAND, OVER.
3-62. Once the pilot identifies the site, the pathfinder issues final landing instructions. If the controller
already has other aircraft flying in a traffic pattern, he places the incoming aircraft into the traffic pattern at
a safe and convenient location. Then, he instructs the pilot to report base. When the pilot reports base, the
pathfinder issues final landing instructions. For special situations, instead of placing the aircraft in the
traffic pattern, the controller might tell the pilot to circle left or right. Then the controller will issue final
landing instructions.
Departure Instructions
3-63. If the departure heading differs from the land heading, the controller gives the departure heading
as the first element of the departure instructions.
Pilot: LIMA ONE SIX, THIS IS BRAVO TWO SEVEN, READY FOR
DEPARTURE, OVER.
Pathfinder: THIS IS LIMA ONE SIX, WIND THREE TWO FIVE AT EIGHT, CLEAR
TO DEPART, STATE INTENTIONS, REPORT CLEAR OF LANDING
ZONE, OVER.
Pilot: THIS IS BRAVO TWO SEVEN, RIGHT BREAK, AFTER DEPARTURE,
OVER.
Pathfinder: THIS IS LIMA ONE SIX, ROGER, OVER.
Pilot: THIS IS BRAVO TWO SEVEN, CLEAR TO THE WEST, OVER.
Pathfinder: THIS IS ALPHA ONE LIMA ONE SIX, ROGER, OUT. |
3-21.38 | 46 | Chapter 3
SITUATION 2, AIRCRAFT REPORTING FROM A CARDINAL DIRECTION AND DISTANCE
3-64. Often, units conduct mutually-supporting helicopter operations to increase the security of an LZ
operation. For example, a team of observation and attack helicopters might screen the LZ
3-65. Because no aircraft plan to land there, and because the utility or lift aircraft know the LZ and
screen team's location from communications over internal UHF or VHF radio nets, the screening
helicopters need not contact the pathfinder. However, if they learn an aircraft does need to land at the LZ,
the screening helicopter team responds differently to initial contact.
3-66. Due to a possible conflict with aircraft departing the landing site in the same direction, the
pathfinder must track the inbound aircraft's course and advise mission aircraft of the unexpected arrival. To
accurately track the aircraft and control the situation, the pathfinder uses a commonly known point in the
direction of the aircraft. He can use a prominent terrain feature, a checkpoint, or an aerial control point
previously established by the ground unit for maneuver control. This situation matches Situation 1 exactly,
except that the controller does not give the aircraft's heading and distance.
SITUATION 3, AIRCRAFT WITH IN-FLIGHT EMERGENCY
3-67. An in-flight emergency occurs when an aircraft develops a mechanical problem that challenges
the pilot's ability to maintain control. Because the pilot must focus on the problem with the aircraft, the
pathfinder helps by moving other air traffic away from the one having the problem, which has first priority.
If the emergency develops before initial contact, OPSEC requires a full information exchange, just like in a
standard transmission. After the pilot declares the emergency, the situation continues as follows:
Pilot: ALPHA ONE LIMA ONE SIX (A1L16), THIS IS CHARLIE ZERO
WHISKEY ZERO TWO (C0W02), IN-FLIGHT EMERGENCY
(MAYDAY), OVER.
Pathfinder: THIS IS LIMA ONE SIX, WIND ZERO THREE FIVE AT SIX, CLEAR TO
LAND, STATE INBOUND HEADING, OVER.
Pilot: THIS IS WHISKEY ZERO TWO, HEADING TWO SIX ZERO, OVER.
Pathfinder: ALL STATIONS, THIS IS ALPHA ONE LIMA ONE SIX, BE ADVISED,
IN-FLIGHT EMERGENCY APPROACHING FROM THE EAST,
REMAIN CLEAR OF LANDING SITE AND MAINTAIN RADIO SILENCE
UNTIL EMERGENCY HAS BEEN TERMINATED - BREAK - WHISKEY
ZERO TWO, CAN I BE OF FURTHER ASSISTANCE, OVER.
Pilot: THIS IS WHISKEY ZERO TWO, NEGATIVE, OVER.
Pathfinder: THIS IS LIMA ONE SIX, ROGER, OVER.
3-68. The controller tells the emergency aircraft of any aircraft that remain on the landing site.
Pathfinder: WHISKEY ZERO TWO, BE ADVISED, TWO UNIFORM HOTEL ONES
ON NORTH END OF SITE. |
3-21.38 | 47 | Air Traffic Control
3-69. Only the pilot who originally declared the emergency can terminate that same emergency. Once
the pilot does so, the pathfinder transmits a net call to inform all stations that normal operations
can continue.
Pathfinder: ALL STATIONS, THIS IS ALPHA ONE LIMA ONE SIX, EMERGENCY
HAS TERMINATED, I CAN ACCEPT TRAFFIC, OVER.
3-70. Departure instructions are the same as those given for Situation 1.
SITUATION 4, DISORIENTED AIRCRAFT
3-71. During limited visibility, adverse weather, in-flight emergencies or, when he has no map, a pilot
might not know the location of the LZ. Also, he might not see any easily-identifiable land point.
3-72. In such cases, the pathfinder can help the pilot by directing him either to a known location or to
the LZ. At terrain flight altitudes, and in some environments, the pilot might experience disorientation of as
little as 200 meters. The pathfinder might hear but not see the aircraft. Pilots who have FM homing
equipment onboard might use that to orient themselves during the initial contact, without having to ask for
a long or short count. Because it requires the ground station to increase transmissions, FM homing risks
loss of signal security (SIGSEC).
3-73. In this example, an aircraft at the CCP cannot establish voice communication with the pathfinder
due to low altitude or radio interference. Knowing the LZ location, but unsure of the exact location of the
landing site, the pilot continues his flight closer to the center of the zone.
Pilot: ALPHA ONE LIMA ONE SIX (A1L16), THIS IS CHARLIE TWO ECHO
THREE FOUR (C2E34), OVER.
Pathfinder: CHARLIE TWO ECHO THREE FOUR, THIS IS ALPHA ONE LIMA
ONE SIX, OVER.
Pilot: THIS IS ECHO THREE FOUR, FOUR UNIFORM HOTEL ONES
(UH-1s) ARE INBOUND FOR LANDING, REQUEST NAVIGATIONAL
ASSISTANCE, OVER.
Pathfinder: THIS IS LIMA ONE SIX, DO YOU HAVE FM HOMING CAPABILITY?
Pilot: THIS IS ECHO THREE FOUR, AFFIRMATIVE, OVER.
Pathfinder: THIS IS LIMA ONE SIX, SHORT COUNT FOLLOWS:
1-2-3-4-5-5-4-3-2-1. END SHORT COUNT, STATE INBOUND
HEADING, OVER.
Pilot: THIS IS ECHO THREE FOUR, SAY AGAIN, OVER.
Pathfinder: THIS IS LIMA ONE SIX, ROGER, ORBIT PRESENT LOCATION,
DESCRIBE PROMINENT TERRAIN FEATURES, STATE LAST
KNOWN LOCATION, HEADING, AND DISTANCE FLOWN, OVER.
Pilot: THIS IS ECHO THREE FOUR, CCP HEADING THREE SIX ZERO,
TWO THOUSAND METERS, I SEE A THREE-ACRE POND WITH
DAM ON THE SOUTH, ORIENTED EAST-WEST, OVER.
Pathfinder: (Plots the course correction and continues with the standard
transmission.) THIS IS LIMA ONE SIX, HEADING TWO NINE ZERO,
EIGHT HUNDRED METERS, (gives advisories if any), OVER.
3-74. The standard ATC information continues as in Situation 1 and ends with—
Pathfinder: DESCRIBE PROMINENT TERRAIN FEATURES EN ROUTE, OVER. |
3-21.38 | 49 | THIS CHAPTER IMPLEMENTS QSTAG 585 AND STANAGs 3281 AND 3619.
Chapter 4
Helicopter Landing Zones
Helicopter landing zones contain one or more helicopter landing sites. Each landing
site has a control center and, in most cases, a manned or unmanned release point
(STANAG 3619). Each landing site might have one or more specific landing points
for individual aircraft to touch down.
SECTION I. SELECTION OF LANDING SITES
The ground unit commander coordinates with the supporting aviation unit to select helicopter landing zones
that can support the ground tactical plan.
CONSIDERATIONS
4-1. Tactical considerations are those that pertain to the actual mission of the supported ground unit.
These considerations are the responsibility of the ground unit commander and staff. The pathfinder must
understand the ground tactical plan to best support the ground unit and facilitate mission accomplishment.
TACTICAL CONSIDERATIONS
4-2. These include—
y An estimate of the situation based on METT-TC.
y The location of the objective in relation to the tentative HLZ.
y The size and type of unit being supported.
TECHNICAL CONSIDERATIONS
4-3. These pertain to the technical aspect of the operation of a day or night HLZ. These are the
responsibility of the pathfinder. The minimum landing space requirements and minimum distance between
helicopters on the ground depend on many factors. If the aviation unit SOP fails to spell out these
requirements, the aviation unit commander works with the pathfinder leader. The final decision about
minimum landing requirements rests with the aviation unit commander. In selecting helicopter-landing
sites from maps, aerial photographs, and actual ground or aerial reconnaissance, the pathfinder considers
the following factors (Figure 4-1, page 4-2):
NUMBER AND TYPE(S) OF HELICOPTERS
4-4. To land a large number of helicopters at the same time, the commander can provide another
landing site(s) nearby or he can have the helicopters land at the same site, but in successive lifts. A larger
site might also be required for cargo aircraft with external loads as compared to several utility aircraft. The
required size of the site is determined by the size and number of aircraft that will be required to land at a
given time. A landing point, or touchdown point (TDP), is the specific point on the ground for a specific
aircraft. The size of the landing point is determined by the aviation unit commander and is based on—
y Pilot or unit proficiency.
y Size and type of aircraft.
y Atmospheric conditions. |
3-21.38 | 50 | Chapter 4
y Visibility (day/night).
y Type of mission (insertion, extraction, resupply, slingload drop-off, forward area arming and
refuel point [FAARP], and so forth).
Figure 4-1. Landing point sizes.
4-5. Standard landing point uses and types of aircraft are listed in Table 4-1. Standard landing point
sizes are listed in Table 4-1.
4-6. In a landing site, pathfinders measure the minimum distances between landing points, from center
to center. When aircraft sizes vary, pathfinders separate landing points by the most generous measure,
allowing 100 meters for size 5; 125 meters for size 6; 150 meters for size 7, measured center to center on
the landing points.
4-7. The aviation unit commander, during coordination, might have authorized pathfinders to reduce the
TDP by one size. Reducing TDP is a last-resort means to make an HLZ suitable to accomplish the mission.
TDP sizes are reduced in a deliberate manner after careful consideration of all factors. If mixed aircraft
types will use the TDP, the size should be reduced for utility (lighter) aircraft before slingload aircraft. |
3-21.38 | 51 | Helicopter Landing Zones
Landing Minimum Diameter
Point Of Landing Point Type Of Helicopter/Operation
Size 1 80 ft (25 m) Light observation helicopters such as the OH-6 and OH-58D.
Size 2 125 ft (35 m) Light utility and attack helicopters such as the UH-1H, H-65, and
AH-1W.
Size 3 160 ft (50 m) Medium utility and attack helicopters such as the UH-60, H-2, and
AH-64.
Size 4 265 ft (80 m) Cargo helicopters such as the CH-47, H-3 and CH-53, or with prior
coordination
Size 5 328 ft (100 m) Slingload helicopters and aircraft of an unknown origin.
Size 6 410 ft (125 m) Slingload long-line operations.
Size 7 492 ft (1,505 m) Slingload operations with night vision goggles (NVG).
Table 4-1. Landing point uses.
LANDING FORMATIONS
4-8. Helicopter pilots should try to match the landing formation to the flight formation. Pilots should have
to modify their formations no more than necessary to accommodate the restrictions of a landing site
(Figure 4-2, page 4-4), but it might be necessary to land in a restrictive area. TDPs are established in the
same order as indicated in the formation.
SURFACE CONDITIONS
4-9. Pathfinders choose landing sites that have firm surfaces; are free of dust, sand, and debris that might
create problems when disturbed by rotor wash; and are cleared of obstacles.
Choose a Hard Surface
4-10. Pathfinders choose a landing point with a hard surface to support the weight of the aircraft to
prevent helicopters from becoming mired, creating excessive dust, or blowing snow. The surface of the
landing point must allow a fully-loaded helicopter to land, restart, and leave again, all without sinking into
the ground. If the surface does not meet these conditions, an advisory must be given and the aircraft must
either terminate at a hover or touch down while under power. If the mission is one that requires the aircraft
to firmly land, such as an FAARP or unload an internal load, a new site must be selected.
Clear to Ground Level
4-11. Pathfinders must clear the entire landing point of any loose material that the rotors could blow up.
The term is “cleared to ground level.” Unless a fire risk exists, they need not clear grass less than 0.3 meter
(1 foot) high, as long as the field is level. They can cut down on dust by wetting down dry dirt. They can
reduce snow to reveal hazards, and then pack it down firm, which will also reduce the amount blowing
around. Rotor wash stirs up any loose dirt, sand (brownout), or snow (whiteout). This can obscure the
ground and other aircraft, especially at night. If a site must be used with obscuring conditions, pathfinders
note these conditions and provide advisories and radio guidance as required. Pathfinders also remove any
debris from landing points because airborne debris could damage the rotor blades or turbine engine(s). |
3-21.38 | 52 | Chapter 4
Figure 4-2. Standard flight and landing formations. |
3-21.38 | 53 | Helicopter Landing Zones
Clear Around Obstacles
4-12. Ground troops must do everything they can to improve landing point surfaces so aircraft can land.
In general, an obstacle is a stump, rock, hole, or other object, 18 inches or larger, that might damage the
aircraft or impede aircraft landing. No obstacles can be in a TDP in which an aircraft is going to land.
Note, however, that even if pathfinders cannot clear ground obstructions, they can perform some helicopter
operations without the helicopter landing. They must still clear and mark the area just as they would if the
helicopter were going to land. Helicopters are given an advisory and hover above the ground obstructions
that prevent them from landing.
GROUND SLOPE
4-13. Pathfinders choose landing sites with relatively level ground. For the helicopter to land safely, the
slope should not exceed 7 degrees (Figure 4-3, page 4-6). Whenever possible, pilots should land upslope
rather than downslope. All helicopters can land where ground slope measures 7 degrees or less and no
advisory is required. When the slope exceeds 7 degrees, observation and utility helicopters that utilize
skids for landing must terminate at a hover to load or off-load personnel or supplies. When the slope
measures between 7 and 15 degrees, large utility and cargo helicopters that use wheels for landing are
issued an advisory, and they land upslope. When the slope exceeds 15 degrees, all helicopters must be
issued an advisory and terminate at a hover to load or off-load personnel or supplies.
Note: To determine slope in percentage or degrees, express all measurements in either feet or
meters, but not both. If the map sheet expresses elevation in meters, multiply by three to convert
into feet. If the map sheet expresses elevation in feet, divide by three to convert to meters.
CAUTION
Never land an aircraft facing downslope, if possible. |
3-21.38 | 54 | Chapter 4
Figure 4-3. Determination of ground slope. |
3-21.38 | 55 | Helicopter Landing Zones
APPROACH AND DEPARTURE DIRECTIONS
4-14. Ideally, to land or take off, especially at night, the helicopter pilot generally chooses the approach
or departure path facing into the wind, over the lowest obstacle, and along the long axis of the site. The
departure heading must be within 45 degrees left or right of land heading.
Prevailing Wind
4-15. Always attempt to land a helicopter facing into the wind. Wind direction within 45 degrees left or
right of land heading is considered a head wind. Depending on the helicopter's capabilities, if only one
direction offers a good approach, or to make the most of available landing area, the pilot might be able to
land with a crosswind of 0 to 9 knots or a tailwind of 0 to 5 knots. When wind speeds exceed 9 knots, the
pilot must land into the wind. The same considerations apply to departures from landing sites. Except when
the crosswind velocity exceeds 9 knots during a landing, the prevailing wind requires less attention than it
does on the approach and departure routes. The wind affects smaller aircraft more than larger, more
powerful ones.
Approach and Departure Obstacle Ratio
4-16. For HLZs that are bordered on the approach and departure ends by tall obstacles such as trees,
power lines, or steep mountains, planners figure on an obstacle ratio of 10 to 1. That is, if a helicopter must
approach or depart directly over a 10-foot tall tree, then the landing point must have 100 feet of horizontal
clearance. If they have coordinated with the aviation unit commander, qualified pathfinders might have the
authority to reduce the obstacle ratio to no less than 5 to 1. Reducing obstacle ratio is a last-resort means to
make an HLZ suitable to accomplish the mission, second only to reduction of TDP size. Obstacle ratios are
reduced in a deliberate manner after careful consideration of all factors, and only to the minimal reduction
possible. The obstacle ratio should first be reduced over the route that the helicopters will be the lightest.
For example, if the mission of the aviation unit is an insertion, they will be loaded on the approach and will
require the most power to ingress and land, needing the longest glide path possible. After the unloading of
troops and equipment, the aircraft will be lighter and will be able to use a shorter departure route. In this
case, the pathfinder would reduce the obstacle ratio on the departure end and maintain a 10 to 1 or greater
ratio on the approach end (Figure 4-4).
Figure 4-4. Maximum angle of approach (daylight). |
3-21.38 | 56 | Chapter 4
Night Approach
4-17. Within the night approach and exit path, the maximum obstruction angle should not exceed 4
degrees measured from the center of the landing point to a distance of 3,000 meters (9,843 feet,
Figure 4-5). The maximum obstacle height at 3,000 meters is 210 meters (689 feet). The field-expedient
formula is that for every meter of vertical obstacle, you must have 14 meters from the center of the landing
point to the obstacle. That is, a landing point must be 280 meters from a 20-meter tree if the helicopter
must approach or exit directly over the tree. Another night operation planning consideration is the
helicopter approach and exit path area and the maximum obstacle height within that area. These criteria
apply to both the approach path to the landing point as well as the exit path from the landing point. First,
we must define the area that is the approach and exit path.
Figure 4-5. Maximum angle of approach (night).
APPROACH AND EXIT PATH
4-18. The approach and exit path is a 16-degree (277 mils) sector or arc extending outward and is
measured from the center of the landing point (Figure 4-6). The "V"-shaped approach and exit path is
shown by the dashed and dotted line in the illustration. The 4-degree maximum obstruction angle applies to
the entire area within the approach and exit path (both the dark and light shaded area) measured from the
landing point center to a distance of 3,000 meters.
Figure 4-6. Approach and exit path. |
3-21.38 | 57 | Helicopter Landing Zones
Night Operations
4-19. During night operations, as the pilot gets closer to the landing point, he needs a wider area for a
safe approach than just the 16-degree sector. Therefore, the minimum width of the approach and exit path,
illustrated by the darker shaded area, must be equal to or wider than the width of the landing point that
must be cleared to a maximum height of 2 feet (Figure 4-1). The length of the minimum width area,
dimension X, will vary depending on the size of the landing point (Table 4-2). Follow along as we use a
UH-60 Blackhawk as an example to help clarify the night approach and exit path criteria. Table 4-1
identified the UH-60 Blackhawk as a size 3 helicopter. Next, you must determine the landing point area
that must be free from obstructions and grass cut to maximum height of 2 feet. Figure 4-2 shows 50 meters
as the area needed for a size 3 landing point. Therefore, the minimum width of the night approach and exit
path is 50 m. The minimum width distance intersects the 16-degree V-shaped arc (night approach and exit
path) 180 meters from the center of the landing point. In other words, the night maximum obstruction angle
applies to the complete approach and exit path; both the rectangular-shaped wedge (dark shaded area of the
diagram) as well as the 16-degree "V"-shaped arc (light shaded area and dotted line).
Table 4-2. Length of minimum width area.
Note: The aviation unit commander makes the final decision on minimum landing requirements.
He bases his decision on the effects of air density, slope, and surface conditions. He explains
these requirements verbally during early mission planning.
Along the Long Axis
4-20. Allows the pilot a better opportunity to identify the TDP and obstacles, select the best flight path,
and prevent overflying the TDP. It also allows the pathfinder to maximize the space available in the site.
DENSITY ALTITUDE
4-21. Altitude, temperature, and humidity determine the density altitude. As each of these conditions
increase, aircraft lift capabilities decrease. Planners should try to remember that as the density altitude
increases, the size of the LZ also increases. This will also be a consideration for the aviation unit
commander when determining the authority for Pathfinders to reduce TDP size or obstacle ratio.
LOADS
4-22. When fully loaded, most helicopters can neither climb nor descend vertically. They need a larger
area and better approach or departure routes than when they carry lighter loads. Other load
considerations are—
y Equipment or personnel.
y Internal or external load. |
3-21.38 | 58 | Chapter 4
y Insertion or extraction mission.
y Weight.
OBSTACLES
4-23. These include any obstruction that might interfere with aircraft operation on the ground. Landing
zones should have no tall trees, power lines, or similar obstructions on the landing site. Pathfinders must
remove or reduce any obstacles within the landing site. This includes any rocks, stumps, holes, and thick
grass or brush that might hinder safe landing over 0.45 meters (18 inches). Obstacles that cannot be
removed or reduced must be marked (preferably in red) and an advisory given to the pilots. Marking will
be done as follows:
y If the obstacle is on the approach route, both the near and far sides of the obstacle will
be marked.
y If the obstacle is on the departure route, only the near side of the obstacle will be marked.
y If the obstacle protrudes into the LZ, but not on the flight route, the near side of the obstacle
will be marked.
y Large obstacles on the flight route and on the LZ will be marked on all sides of the obstacle. At
a minimum, one light is required on each of the four sides.
ALTERNATE SITES
4-24. Enemy action, unfavorable terrain, or changes in the tactical or logistical situation can require
alternate landing sites. The ground unit commander usually selects these to support the tactical plan. He (or
his representative) decides when to use them based on the recommendations of the aviation unit
commander and the pathfinder on the site. The commander uses the fastest means to get instructions for
using alternate sites to the pathfinders. Neither pathfinder nor aviation unit commanders can shift to an
alternate LZ(s) unless the supported ground unit commander has delegated that authority to them.
SECTION II. ORGANIZATION AND DUTIES
The commander task organizes the pathfinder element to set up and operate the installations required by the
supported unit's tactical plan. They might set these up within a single LZ or separate them widely throughout a
large AO. The pathfinder leader normally stays at the most important site. To set up and operate one helicopter
LZ, the commander task organizes the pathfinder element into two working parties: a reconnaissance party and
a marking party. Each site requires its own landing site party. The control center party and the release point
party provide the same function for LZs or DZs.
CONTROL CENTER
4-25. The control center (CC) coordinates aircraft in and around an LZ or DZ and promotes a safe,
orderly, and speedy flow of air traffic. Upon arrival in the area, the pathfinder leader selects the exact
location of the CC. He positions it to allow visual control of aircraft in and around the LZ or DZ.
4-26. For helicopter LZs, the most desirable CC location is along the aircraft flight route, but displaced
from the landing site. This helps prevent enemy EW assets from compromising the actual landing site
location, even if the tactical situation dictates that the pathfinder leader remain on the site for control
purposes. For an LZ with more than one landing site, or for any LZ during reduced visibility, the
pathfinder leader locates the CC where it can act as a manned RP or final approach fix to provide positive
navigational assistance to arriving aircraft.
4-27. The RP is an established traffic control checkpoint. It is the final navigational checkpoint for
aircraft approaching the landing site or approaching air-delivery facilities in an LZ or DZ.
4-28. During the air movement phase of an air assault operation, helicopter serials also use the RP as a
final coordination point for control of planned ground or aerial supporting fires in and around LZs. The air |
3-21.38 | 59 | Helicopter Landing Zones
movement commander staffs the RP only when he expects tough navigational problems. He tentatively
chooses its location from maps or from aerial photographic studies. He looks for an easily-identifiable
point on the planned flight route to the landing site. He looks for a location that will take advantage of
long-range electronic and visual navigation aids.
4-29. For single helicopter landing sites within a single LZ, the site itself offers the best location for
GTA communication. Especially at night, positioning here allows the pathfinder air traffic controller to
observe the final approach of helicopter formations. It helps him make sure pilots align correctly on the
required landing direction. It also helps him ensure that they clear any obstacles.
4-30. The pathfinder leader organizes the control center to meet mission requirements. The control center
can consist of a single pathfinder. This Soldier can operate the GTA radio for a limited period at a small
site, or the control center can consist of the following staff:
LZ OR DZ COMMANDER
4-31. He supervises aircraft landings and departures, airdrops, and other pathfinder activities in the LZ or
DZ. He might also serve as the GTA radio operator.
GTA RADIO OPERATOR
4-32. He operates the radio used to maintain communications with pilots. He also provides advisories for
his airspace as needed.
INTERNAL NET RECORDER
4-33. Some situations require pathfinders to set up an internal net to communicate with other pathfinder
elements. An internal net recorder (INR) runs this net and helps control aircraft at his HLZ. He logs details
of all arrivals and departures on DA Form 7461-R, Internal Net Record, (Figure 4-7, page 4-12). If an
aircraft fails to arrive at its destination, search and rescue medical units check the DA Forms 7461-R so
they know where to focus their search. The recorder might copy the blank, reproducible form from the
back of this manual onto 8½ by 11-inch paper. He might also download it from http://www.usapa.army.mil
or copy it from the Army Electronic Library (AEL) CD-ROM (EM0001). Then he completes the form
as follows:
PFDR Det. Write the name of the pathfinder detachment operating the landing zone.
Supported Unit. Write the name of the supported unit.
Period (DTG). Write the date and time of the mission.
Operation. Write the name of the mission.
Designation. Write the name and location of the site.
Recorder. Write your name.
No. A/C. Write the number of aircraft in the formation.
Type A/C. Write the nomenclature of each type of aircraft in the formation.
Contact Time. Write the time of the initial contact with the flight commander.
Call Sign. Write the flight commander's call sign.
Time, Arr. Write what time the aircraft or formation inserted.
Time, Dep. Write what time the aircraft or formation extracted.
Load Type, Ins. Write what type of load the aircraft inserted.
Load Type, Ext. Write what type of load the aircraft extracted.
Destination. Write the name of the aircraft's or formation's destination on leaving.
Remarks. Write anything else here that you think you need to record. |
3-21.38 | 60 | Chapter 4
LANDING SITE PARTY
4-34. The landing site party consists of a site team leader and other pathfinders and attached personnel,
as required. A single pathfinder might establish and operate a small landing site for a limited time. He
maintains a record of all aircraft and their respective cargos on DA Form 7461-R, Internal Net Record.
Figure 4-7 shows an example of the completed form. A blank copy is provided in the back of this book for
local reproduction on 8 1/2- by 11-inch paper. The form may also be downloaded from the Internet at
Army Knowledge Online (http://www.army.mil/usapa/eforms/) or the Army Publishing Directorate Web
site (http://www.apd.army.mil/USAPA_PUB_formrange_f.asp).
Figure 4-7. Example completed DA Form 7461-R.
SITE TEAM LEADER
4-35. The site team leader reconnoiters, establishes, and operates the landing site. He supervises it and, at
any time, might supervise the GTA radio operator. Some of his responsibilities include the following:
y Organizing at an objective rally point.
y Reconnoitering to determine—
-- Long axis.
-- Usable area.
-- Ground slope (compute).
-- Land heading.
-- Best landing formation.
y Designating sling-load point(s). |
3-21.38 | 61 | Helicopter Landing Zones
y Emplacing and briefing the GTA radio operator.
y Clearing touchdown and slingload points.
y Organizing personnel and loads for air movement.
y Clearing or marking obstacles.
y Preparing for night and day missions.
y Continuing to improve the site.
EXTRA PATHFINDERS
4-36. These Soldiers operate the GTA radio and the pathfinder internal radio net (if established), position
and operate navigation and assembly aids, and clear or mark obstacles. Four factors dictate the number of
extra pathfinders employed:
y The size of the landing site.
y The expected density of air traffic.
y The number and type of visual and electronic aids used.
y The tactical situation.
COMMANDER
4-37. The commander can attach other Soldiers from supported units to the landing site party. The
pathfinders brief and rehearse attached Soldiers. Only pathfinders reconnoiter actual landing areas, but
attached personnel can—
y Reconnoiter other areas.
y Provide security.
y Help pathfinders set up and operate the landing site.
y Reconnoiter and mark assembly areas.
y Operate assembly aids.
SECTION III. LANDING SITE OPERATIONS
Before they can start using a landing site, pathfinders need only pick its location and set up communications
there. They continue marking and improving the site until it can support the ground tactical plan.
COMMUNICATIONS
4-38. As soon as they arrive at the landing site, pathfinders set up communications in the GTA net. If
needed, they also set up the pathfinder internal net. They monitor these radio nets continuously, unless
directed otherwise, until they complete operations at the site.
4-39. Tactical situation permitting, pathfinders locate each helicopter landing site within ground
communication range of the other sites and manned RPs. The range of available radios dictates whether
facilities within the LZ can communicate with each other.
4-40. The commander of the landing site for utility and cargo helicopters quickly reconnoiters the area to
determine the exact direction of landing. He calculates an intercept heading from the RP if necessary. He
selects the location of the landing point of the lead helicopter of each flight. Then he decides if the terrain
or situation dictates any change to the planned landing formation. The site commander has pathfinders or
other personnel compile landing instructions for transmittal to inbound helicopters. He also has them
remove or mark obstacles in or around the site. |
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FLIGHT FORMATIONS
4-41. Ideally, all helicopters land at the same time in a planned flight formation. The landing site
commander includes this information in his landing instructions to the flight leader. Pathfinders lay out the
landing site in a location where helicopters will not fly directly over aircraft on the ground. The layout of
the site also depends on the landing space available, the number and type of obstacles, unit SOPs, and
prearranged flight formations.
LANDING ZONE AND OBSTACLE MARKINGS
4-42. For daylight operations, pathfinders use only panels or some other minimal identification means to
mark LZs (Figure 4-8 through Figure 4-11, pages 4-15 through 4-18). Smoke might also be used to
identify an LZ and assist the pilot in determining wind conditions. However, smoke is also easily identified
by the enemy. For daylight operations, mark the number one landing point using a single VS-17 panel,
with the international orange side visible. Other TDPs might be marked, as coordinated. Mar obstacles
using the cerise colored side of the panel. For night operations, they use chem-lights, lanterns, field
expedients, or other methods to show the direction of landing and to mark individual landing points
(Figure 4-12 and Figure 4-13, pages 4-19 and 4-20). For day and night air assault operations, they mark all
obstacles. (Section V provides detailed information about conducting night operations.)
4-43. At night, pathfinders can use lights of different colors (except red, which marks obstacles) to
designate different helicopter sites or to separate flights within a larger formation. A lighted "T" or inverted
"Y" indicates both the landing point for the lead helicopter of each flight and the direction of approach
(Figure 4-14, page 4-21). Other lights mark touchdown points for the other helicopters in the flight. Each
helicopter should land with its right landing gear or its right skid 5 meters left of the lights. Large cargo
helicopters (CH-47) land 10 meters to the left of the lights.
4-44. For security, pathfinders and the ground unit turn off, cover, or turn all lights upside down until the
last practical moment before a helicopter arrives. Then they orient the lights in the direction from which the
lead helicopter is approaching, and a signalman directs its landing.
Note: Because the marking lights could be too bright for the aircrew member's NVGs, he might
have to look under it to distinguish the colors. Also, aircrew members wear NVGs with filtered
lenses. These filters do not allow the aircrews to see blue or green chem-lights. Colors such as
yellow, orange, red, and infrared can be seen by pilots wearing ANVIS.
AIR ASSAULTS
4-45. During daylight air assault operations, pathfinders use red-colored panels or other red,
easily-identifiable means to mark any hard-to-detect, impossible-to-remove obstacles such as wires, holes,
stumps, and rocks. During nighttime air assault operations, pathfinders use red lights to mark any obstacles
within the landing site that they cannot reduce or remove.
4-46. In most combat situations, the need for security keeps pathfinders from using red lights to mark
treetops on the departure end of a landing zone. However, in training or in a rear area landing site, they do
use red lights. If they cannot mark obstacles or hazards, they must fully advise aviators of existing
conditions by GTA radio. In any case, the pathfinder landing site leader makes sure that pathfinders mark
the most dangerous obstacles first and, if possible, that they remove them.
4-47. If required to do so by the supported unit, pathfinders can mark initial assembly points for troops,
equipment, and supplies. They should choose locations that help ensure the quick, efficient assembly and
clearing of the helicopter site. If the unit will use the assembly areas, the ground unit commander selects
their locations. If needed, supported ground unit Soldiers go with the pathfinders to reconnoiter and mark
the unit assembly areas, set up assembly aids, act as guides, and help with landing and unloading |
3-21.38 | 63 | Helicopter Landing Zones
operations. Having this help ensures that the pathfinders can rapidly clear troops, supplies, and equipment
from the landing points.
4-48. Pathfinders have a limited capability to secure a landing site. If they precede the initial assault
elements into a landing site, Soldiers from the supported ground unit can go with them for security. |
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Figure 4-8. Helicopter day landing site, staggered trail-right formation. |
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Figure 4-9. Helicopter day landing site, echelon right formation. |
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Figure 4-10. Day or night slingload operation site. |
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Figure 4-11. Day or night cargo landing site, "V" formation. |
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Figure 4-12. Night landing site with landing points
for aircraft and slingloads. |
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Figure 4-13. Utility helicopter night landing site, diamond formations. |
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Figure 4-14. Lighted night landing symbols as the pilot would see them from different approach angles. |
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INTERCEPT HEADINGS
4-49. The heading from the RP (or from the CCP if the pathfinders do not use an RP) to the landing site
coincides as closely as possible with the landing direction to keep the helicopter from having to turn
sharply. The larger the formation, the more important this becomes. If a pilot cannot approach the landing
site straight on, pathfinders will set up an intercept heading (Figure 4-15). They choose an intercept point
far enough from touchdown to allow helicopters in formation a final approach of at least 1 to 2 miles.
Flight leaders might need visual steering commands, time and distance information, terrain features, and
electronic or visual navigation aids to help them determine the intercept point and the landing direction at
the landing site.
Figure 4-15. Intercept heading technique.
SECTION IV. LANDING ZONE OPERATIONS
Helicopters approach the LZ along a designated flight route. They normally travel in serials containing four or
five helicopters, but they sometimes travel as platoon-sized lifts. One serial might contain a flight for each
helicopter site. Flights of medium or heavy transport helicopters (CH-47) carrying artillery or other bulk cargo
often arrive at LZs one or two helicopters at a time (Figure 4-16). Later flights follow at the smallest time
intervals. These intervals depend on the number of helicopters in each flight, the configuration and conditions
of the landing site, and the nature of the cargo to be loaded or unloaded. During planning, the aviation unit
commander determines the time between successive flights. Once an operation starts, pathfinders at the site
recommend any changes needed to ensure helicopter safety or expedite operations. Night operations often
require more time and distance between formations.
COMMUNICATIONS CHECKPOINT
4-50. As each helicopter serial reaches the CCP on the flight route, the flight leader contacts the
appropriate helicopter landing site control center.
4-51. The CC then gives the flight leader the heading from the CCP to the landing site, the landing
direction, and other relevant and important information, as follows:
y Enemy situation.
y Friendly fires. |
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y Field elevation.
y Landing formation.
y Terrain conditions.
y Traffic situation.
y Obstacles.
y Availability of visual signals (smoke, light gun, and so forth).
y Next reporting point.
Figure 4-16. Terrain flight modes.
4-52. Before reaching the CCP, IAW instructions from the flight leader, all helicopters in a flight switch
to the pathfinder control frequency.
Note: Pathfinders must stay prepared to provide ATC and navigational aid to all aircraft in and
around the landing site in case those aircraft have no specified flight plan.
4-53. The helicopter formation continues along the flight route to the RP. The electronic and visual aids
at the RP (if manned) help pilots navigate. As each helicopter passes over or near the RP, its flight serial
leader reports this to the respective landing site CC. Then the helicopter flies directly to the assigned
landing site. The CC at the individual landing site uses visual signals, steering commands, or electronic
homing techniques to help any flight that cannot find its landing site.
Day Operation Signals
4-54. For daylight operations, you can use different smoke colors for each landing site. You can use the
same color more than once, just spread them out. Use smoke only if you have to, because the enemy can
see it, too. Try to use it only when the pilot asks for help locating his helicopter site.
Night Operation Signals
4-55. For night operations, IR strobe or other visual signals in lieu of smoke. As in daylight, red signals
mean "DO NOT LAND," but you can also use them to indicate other emergency conditions. All concerned
must plan and know emergency codes. Each flight lands at the assigned site according to CC messages and |
3-21.38 | 73 | Helicopter Landing Zones
the visual aids displayed. You can use arm-and-hand signals to help control the landing, hovering, and
parking of helicopters.
AIR CONTROL POINTS
4-56. Pathfinders might have to manage air control points (ACPs) to help aircraft en route to the LZ.
ACP PARTY RESPONSIBILITIES
4-57. The ACP party consists of two or three pathfinders, or at least one pathfinder and assistants. The
party positions and operates electronic navigation aids, visual navigation aids, or both. The party also
operates radios in the pathfinder internal net (if used) and the GTA net. The ACP party monitors the GTA
net so they can respond at once to any pilot's request for help finding an ACP.
NAVIGATION AID ORDER
4-58. The ACP party installs navigation aids as soon as it arrives at the site or as planned. They try to set
up all of the aids at the same time. However, if they cannot do this because they have too few people, or for
some other reason, then they set them up in the following order:
GTA Radio
4-59. The party sets this up first. Then, if the aviation unit commander has asked them to do so, they
install the electronic homing beacon. This beacon allows the party to offer long-range guidance. If they do
use the beacon, the party sets it up far enough away to prevent excessive radio interference. This also helps
keep the enemy from destroying the radios and the beacon at the same time.
Visual Navigation Aids
4-60. These navigation aids vary in number and type, depending on aviation unit SOPs and requirements
and on the need for security. The ACP party removes any grass or brush that masks their usage of these
aids, but they also plan a way to conceal the markings in case they sight enemy aircraft.
Internal Net Recorder
4-61. The pathfinder internal net recorder sets up communications with the landing zone CCs as fast as
he can. He immediately reports the state of ACP readiness and any information about the local enemy
situation, if any. Unless directed to operate a beacon on a definite time schedule, he constantly monitors
the radio.
Security Personnel
4-62. The ACP party can include attached personnel from the supported units. These personnel provide
security. They both move to their assigned locations and take up security positions, or they help set up and
operate navigation aids and communications equipment.
SECTION V. NIGHT OPERATIONS
Daytime visual references (checkpoints for positive identification) are difficult to see at night. Visual aids for
night navigation emit illumination. Having too few visual references can cause pilots to concentrate on a single
light or group of lights in a concentrated area. This can cause visual illusions, which can then cause vertigo. To
prevent this hazardous situation, pathfinders mark LZs with multiple lights and mark landing areas with two or
more widely separated lights. |
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TACTICAL LANDING LIGHTS
4-63. The tactical landing light system provides visual cues for landing in a tactical landing site. When
the aircraft approaches from terrain flight altitudes, it should use the inverted "Y" system. Aircraft
normally approach a tactical landing site without the aid of the search landing light. The lighting for a
tactical LZ can consist of handheld flashlights or "beanbag" lights arranged on the ground.
4-64. Regardless of the type lighting device used, pathfinders identify the touchdown point with at least
two lights. At night, they can designate different helicopter sites with lights of different colors. They might
also use different colors to separate flights within a larger formation. A lighted (inverted) "Y" indicates the
landing point of the lead helicopter (Figure 4-17).
Figure 4-17. Placement of the inverted "Y" or NATO "T" at the number one touchdown point.
4-65. At night, all landing lights should be placed in directional holes that can only be seen from the
direction of approach and from above, but not from the ground. If this is not possible, the pathfinder turns
his hood upside down, or keeps all lights off for security purposes until the last practical moment.
4-66. At other touchdown points, helicopters land with the right landing gear or skid just to the left of the
light (Figure 4-18). They also place a signalman at a sling-load point. Then they beam the lights in the
direction from which the helicopters approach.
Figure 4-18. Placement of additional touchdown point markings for night use. |
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4-67. Pathfinders display an inverted "Y" for cargo aircraft. This marker consists of five lights.
Pathfinders place the fifth light IAW prior coordination with the supporting aviation unit (Figure 4-19).
The fifth light can go 7 meters from furthest stem light in the direction of landing, or 10 meters opposite
the landing direction (below) the right flank light.
Figure 4-19. Placement of fifth light using inverted "Y," when coordinated.
4-68. Pathfinders will display a NATO landing "T" if an aircraft approaches the LZ from at least 500
above ground level (AGL), or anytime the pathfinders coordinate in advance with the supporting
aviation unit.
4-69. Noncargo aircraft require a 5-meter separation between touchdown point and lights, with a 5-meter
separation between lights.
4-70. Cargo aircraft require a 10-meter separation between touchdown point and lights, with a 10-meter
separation between the lights.
4-71. During darkness, helicopters approach slightly steeper and slower than they would in daylight.
4-72. Vehicle headlights offer one kind of emergency night lighting. Pathfinders place two vehicles
about 35 meters apart and 35 meters downwind of the landing point. They shine their headlights so that
their beams intersect at the center of the landing point (Figure 4-20). The helicopter approaches into the
wind, passes between the vehicles, and lands in the lighted area. This method does not work well for large
helicopters.
Figure 4-20. Emergency night lighting by vehicle headlights. |
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CAUTION
When fully adapted to the night, the eyes grow extremely sensitive to
any light. Sudden exposure to a light source causes partial to complete
loss of night vision. Thus, take care to avoid exposing pilots to light
sources. Also, if pilots are using NVG, avoid shining a light directly at
the aircraft, or use light sources compatible with the NVG.
EXTERNAL LOADS
4-73. Employing external loads presents a challenge in the dark. Even so, the pathfinder can use one of
several methods. If he lacks sufficient signalmen, he marks the load by placing three reference lights 25
meters in front of the load landing and pickup point. He spaces them in a triangle, 5 meters apart. This
helps the flight crew during hookup, liftoff, and landing. On liftoff, the aircraft climbs vertically until the
load clears the ground. As the helicopter begins to move forward, the pilot applies enough power to
maintain a climb that allows the slingload to clear any obstacles on the liftoff path. The shorter the sling,
the less altitude is required to clear obstacles.
MULTIHELICOPTER OPERATIONS
4-74. Only by using NVG can pilots fly safely in formation in a complete blackout and at terrain flight
altitudes.
NIGHT VISION GOGGLES
4-75. To operate at terrain flight altitudes during low- or mid-light levels, pathfinders use night vision
goggles. If the lights used in the tactical lighting and marking are too bright for night vision goggles,
pathfinders must place a filter over the light cover, paint the light covers, cover them with plastic tape, or
use other means to reduce the intensity of the light. The night vision goggles commonly used by aviators
(AN/PVS-8) generally have a filter to prevent the cockpit instruments and lighting from blinding the
aircrew. However, these filters also prevent the aircrew from observing green and blue chem-lights. These
colors might be seen with the unaided eye if the aircrews adjust their goggles to look below them, but they
will not be able to see the light source through the NVDs.
WARNING
When your unit trains with or employs the tactical light set, wear
a filter over your night vision goggles to prevent eye injury. If you
do not have a filter, paint the lens cover or cover it with plastic
tape to reduce light intensity. |
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SECTION VI. ENVIRONMENTAL CONSIDERATIONS
The pathfinder unit can expect to support the aviation commander and ground unit commander in many
climates and types of terrain. The requirements for establishing a landing site or zone are similar. For aircraft to
land safely and quickly in challenging environments, pathfinders must choose and prepare LZs carefully.
PILOT INPUT
4-76. The pilot considers his experiences and his responsibilities to the crew and aircraft before
determining whether a proposed landing site is safe.
4-77. Challenging climatic and terrain environments include extreme hot and cold weather and jungle,
desert, and mountainous terrain. (For more detailed information on the climate, terrain, and operational
aspects of these areas, see FM 90-3, FM 90-5, and FM 3-97.6.)
4-78. Each area requires the pilot to know and follow special procedures. The pathfinder who also knows
these procedures can better advise and assist aviators and the supported ground unit.
COLD WEATHER
4-79. Many parts of the world experience cold weather. Extreme cold and blowing snow pose special
problems in ground operations and flight. Pathfinder mission planning includes considering the problems
presented by ice, snow, or rain. The pathfinder's knowledge of flight procedures helps him advise the pilot
about the existing surface conditions.
COMMUNICATIONS
4-80. Most locations allow generally-good radio communications. However, atmospheric electricity,
such as the aurora borealis, can disrupt them. These events could disturb or block some frequencies.
Mountainous terrain also restricts communications. Pathfinders might need to set up relay stations. "Radio
skipping" happens often in cold weather areas. Radio operators often hear long-distance radio traffic on
tactical FM networks.
NAVIGATION
4-81. In snow-covered areas with flat terrain, pilots might need marked and manned RPs. When aircraft
fly over loose snow, the air movement lifts the snow and circulates it into a snow cloud. This often
produces a zero-visibility condition known as "whiteout," through which the pilot must take off or land
blind (Figure 4-21). Whiteout conditions place extra demands on the landing site party.
SURFACE CONDITIONS
4-82. The pathfinder evaluates the surface of the ground to see whether aircraft can land without sinking
too deep into the snow. He can use a tactical vehicle to test the hardness of the surface. The landing site
party might also try to determine the degree of ground slope, and whether obstacles lie under the cover of
snow at each landing point.
Distance Between Aircraft
4-83. Pathfinders might need to increase the distance between aircraft to 100 meters and the size of the
landing point to 100 meters in diameter.
Landing Point Markings
4-84. Marking the landing points presents other problems. A pilot's depth perception is impaired in
snow-covered areas. A signalman on the ground provides a useful reference for estimating height. In
daytime, pathfinders mark touchdown points so the pilot can find a clear and safe landing area. |
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Whiteouts
4-85. If the tactical situation permits, the GTA radio operator advises the pilot of the surface conditions
so the pilot can plan how to approach. Using the echelon left or right landing formation reduces the effect
of snow clouds (also called "whiteouts") on subsequent landings. The pathfinder plans to stagger aircraft
arrivals to let the snow clouds settle.
Figure 4-21. Lessening the effects of loose snow on the ground. |
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Multiple Landing Sites
4-86. Depending on the mission requirements, climatic conditions, and the expected times of the
landings, the pathfinder leader might decide to use multiple landing sites.
Night Approaches
4-87. Aircraft making night approaches to snow sites need a visual reference point on the ground such as
runway or tactical landing lights. These lights help the pilot judge the angle of descent and rate of closure.
He plans the approach to land short of the touchdown point. This ensures that he does not overshoot the
point and have to decelerate rapidly in the snow cloud produced by his own aircraft. Approaching short
allows the pilot to maintain airspeed after leveling off, and to keep the aircraft in front of the snow cloud
until touchdown.
Adjustment of Inverted "Y"
4-88. If he coordinates with the flight commander before the landing, the pathfinder can adjust his
inverted "Y" forward 10 meters in front of his designated Number 1 touchdown point. This way, the
landing site party takes advantage of all usable areas on the site.
SIGNALMAN
4-89. The pathfinder leader positions any extra personnel to act as signalmen for aircraft approaching
other touchdown points. While aircraft approach and land, he makes sure that signalmen remain in safe
areas. Other signalmen should also control the loading of personnel on the aircraft, as instructed by the
crew chief or the crew. The technique for landing on snow with a slingload resembles other types of
approach, but the pilot hovers at a higher altitude because of the load (A, Figure 4-21). He has a hard time
judging the height of the slingload (the height above the ground) as it nears the snow surface. He relies on
a signalman to keep him informed. To avoid building up a snow cloud, the pilot puts the load on the
ground as fast as he can (B, Figure 4-21).
SLINGLOAD OPERATIONS
4-90. The CH-47 requires a sling length of at least 50 feet. Other aircraft allow a shorter sling. Normally
an aircraft hovers during hookup and liftoff with a slingload. Doing this above snow produces a snow
cloud (B, Figure 4-21). The pilot must expect this and plan for it. In fact, when operating over
snow-covered terrain, the pilot can use the most common technique—hovering the helicopter over the load
while the ground crew attaches the sling to the hook—or not.
4-91. The pilot can land to the left of the load, but close enough for hookup personnel to attach the
sling to it.
4-92. When ready for liftoff, the pilot starts a slow, vertical ascent, with enough lateral movement to
position the aircraft over the load (C, Figure 4-21). He keeps ascending until the load clears the ground,
and then he checks hover power, starts accelerating, and continues to climb.
WARNING
Rotor wash increases the risk of frostbite. Make sure you and
anyone else on the ground dresses for the conditions and keeps
or uses a face mask and goggles. |
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STATIC ELECTRICITY
4-93. During cold weather, static electricity creates serious problems. Moving an aircraft through the air,
brushing snow and ice from an aircraft, or dragging steel cables over the snow can generate static
electricity. During external load operations, aviators key the FM radio just before load pickup. This
discharges the aircraft's static electrical charge. Because the charge rapidly builds up again, hookup
personnel use a grounding device to avoid electrical shock (Chapter 5 says more about static
discharge wands).
SAFETY
4-94. Accumulated ice on aircraft structural and moving parts presents a danger to nearby ground
personnel. The aircraft can accumulate ice up to three-quarters of an inch thick during flight in
temperatures and altitudes where icing conditions exist. During flight at less extreme temperatures, this ice
begins to loosen and fall off. Ice might shed while the helicopter loses altitude during the landing approach
and during touchdown, and pieces of ice shed by the main rotor can fly outward as much as 300 feet.
Ground personnel should stay a safe distance away from helicopters during landing and shutdown (after
flight in icing conditions), and passengers should not exit until the rotor blades have stopped.
JUNGLE
4-95. Jungle areas impede military operations. Jungle areas promise heat, humidity, rainy seasons, and
other weather conditions that reduce aircraft performance.
COMMUNICATIONS
4-96. Jungle tends to obstruct military lines of communication. Thick vegetation, irregular terrain, and
adverse atmospheric conditions screen radio transmissions. The ground or supported might have to use
radio relays. They might also have to staff and mark the CCP. If communications are limited in range,
pathfinders might also have to provide GTA communications to advise and direct the pilot to the
landing site.
LANDING SITES
4-97. Jungle conditions mean small landing sites that can handle only a few aircraft at a time. Small
landing sites also mean a reduced allowable cargo load (ACL). Pathfinders evaluate surface conditions at
the landing site to make sure the aircraft will not sink or bog down in the soil. Then they survey the site for
vines, trees, and other obstructions in the approach path and near the touchdown point.
NAVIGATION
4-98. On an approach to a jungle landing site, the pilot avoids using a high rate of descent. He uses a
steep enough angle of descent to just clear any obstacles. He normally uses a ten-to-one obstacle ratio, but
for a jungle operation, he should reduce this ratio to no less than five to one. Due to density altitude
problems in tropical areas, the aircraft might not be able to develop enough lift to clear tall obstacles. So,
the pathfinder leader considers obstacle height on the approach and departure ends. When site size and
terrain conditions permit, the pilot might run the liftoffs and landings. However, the small size of a jungle
site, soft terrain, or obstacles can keep him from doing so.
LIGHTS
4-99. The tactical situation might restrict the use of lights in nighttime jungle LZ operations. |
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SECURITY
4-100. Success of the ground unit commander's mission relies on site security. Because jungle terrain
provides cover and concealment, landing site security presents a constant challenge. The pathfinder team
leader coordinates with the flight commander to set a specific time to light the site.
LIFTOFFS AND LANDINGS
4-101. The pathfinder orients the site to the direction of the wind. He keeps departure obstacle ratios low
due to climatic conditions, jungle vegetation, and helicopter's reduced lift capability. Because ground
effects reduce the aircraft's lift efficiency, the pilot hovers as low as possible and lingers no longer than
necessary.
DESERT
4-102. The typical desert is a dry, barren region, generally treeless and sandy. It has environmental
extremes, with violent and unpredictable weather changes. Its terrain conforms to no particular model.
Frequent clear days offer unequaled visibility and flight conditions, but a sudden sandstorm immediately
halts all operations. Successful desert operations require special training, acclimatization, and great
self-discipline.
COMMUNICATIONS
4-103. In desert operations, the radio offers the best way to communicate. The low, rolling terrain allows
good radio range. Due to the increased distances involved in military desert operations, FM radio
communications might prove inadequate, especially in the higher FM frequencies. Pathfinders, aircraft, and
ground crew must all have high-frequency radio equipment. Sand or dust in equipment or a poor electrical
ground cause most communication problems. Due to the increased distances between land force units
engaged in desert operations, helicopters might provide air or ground relay or help deploy ground radio
rebroadcast facilities.
NAVIGATION
4-104. Many of the conditions experienced in cold weather operations resemble those in desert operations.
Pathfinders and pilots find distances and altitudes hard to judge in the desert. The lack of definable terrain
features makes navigation difficult, especially at night and over long distances. Also, the sameness of the
terrain can influence a pilot to pay less attention to his surroundings. Pathfinders might have to mark and
man release points.
LANDING SITES
4-105. The climatic conditions in the desert profoundly affect the setup and operation of landing sites.
Most importantly, the pathfinder must consider density altitude, wind, and sand (dust). Sand on a landing
site can produce brownout conditions similar to those in snowy areas, so the same precautions apply. This
makes a rocky area a better landing site than a sandy hollow, depression, or valley.
WIND
4-106. Desert winds generally calm down for an hour or two around sundown. Another calm occurs
before sunrise. Other than those times, desert winds can drive dense clouds of dust and sand with hurricane
force. Strong winds naturally raise dense clouds of dust and sand, and rapid temperature changes often
follow strong winds. The pathfinder leader must consider what times of day the wind will allow him to
operate the landing site.
4-107. The extreme heat often experienced in the desert also affects the aircraft's ACL. When supporting a
ground unit, the pathfinder leader coordinates with the aviation element to determine the ACL for each
type of aircraft. Both the minimum distance between aircraft and the size of the landing point might |
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increase in desert operations: 100 meters between aircraft, 100-meter-diameter landing points. In daylight
hours, ground-crew members mark the touchdown points. They paint sandbags a bright color or mark them
using some other quick method. Ideally, they use signalmen.
4-108. When establishing a landing site, the pathfinder leader considers taxi procedures. When an aircraft
must taxi, the pilot moves it into a vertical position as quickly as possible to reduce the amount of sand
(dust) the engine sucks in as well as to avoid a brownout. Pilots should avoid taxiing over the same area
repeatedly.
LIFTOFFS
4-109. Pilots will not try a normal liftoff in a sandstorm. Helicopters with wheels and airplanes should
make a running-type takeoff. Helicopters with skids should make a maximum performance liftoff.
LANDINGS
4-110. When they can, pilots should use a running-type landing to reduce sand intake. If a pilot can make
a running landing, he keeps the touchdown roll to a minimum to keep from overloading the landing gear. If
the terrain does not permit a running landing, the pilot lands at a greater-than-normal angle. He should
never land from a hover.
SAFETY
4-111. Ground crew personnel should wear clothing that will protect them against the sand blown around
by the rotor wash. Each person on the ground should take special care to keep the sand out of his eyes,
ears, nose, and mouth. Goggles, earplugs, and cloth masks provide adequate protection for facial areas.
Other ground crew procedures resemble those for cold weather operations.
MOUNTAINS
4-112. Mountains have rugged, divided terrain with steep slopes and few natural or man-made lines of
communication. Weather fluctuates seasonally from extreme cold, with ice and snow, to extreme heat.
Also, it can switch between the two extremes very quickly. This unpredictability greatly affects operations.
COMMUNICATIONS
4-113. Mountainous terrain often limits or restricts communications. To maintain communications within
the AO, aircraft might have to limit operations to the vicinity of the unit. Other aircraft can serve as radio
relay stations. Pathfinder units might also have to set up radio relays at the RP, CCP, or both.
4-114. Mountain conditions challenge aviators in pathfinder operations more than any other conditions.
For precise flying in mountainous areas, pilots need large-scale terrain maps.
4-115. Since intervening terrain degrades GTA communications, providing navigational aid and control
over extended ranges might prove difficult.
WIND
4-116. The main weather hazard in the mountains is wind. Even moderate winds (11 to 20 knots) can
produce significant turbulence over mountain ridges. Predicting wind conditions is difficult. The windward
side of a mountain maintains a steady direction of airflow, though the strength of the wind might vary. The
leeward side has turbulent winds with strong vertical currents. This turbulence might prevent assault
landings and require pilots to fly at higher altitudes. This naturally increases the risk of detection and
destruction. |
3-21.38 | 83 | Helicopter Landing Zones
DENSITY ALTITUDE
4-117. In the mountains, density altitude can vary a lot between PZs and LZs. It can also vary greatly from
one time of day to another. It normally peaks in the late afternoon, and drops to its lowest point at dawn.
NAVIGATION
4-118. In the mountains, the helicopter offers the best way to rapidly move forces. In the offense, air
assault operations can insert forces into the enemy's rear area and bypass or envelop his defenses. In the
defense, helicopters can move reinforcements and reserves rapidly.
LANDING SITES
4-119. Mountainous regions offer few, if any, airfields for fixed-wing aircraft, and few LZs suitable for
multiple helicopters.
4-120. If the enemy situation allows, pathfinders set up LZs on the windward side of the mountain
because that side offers more stable winds.
4-121. When they can only find LZs designed for single aircraft, planners increase in-flight spacing. This
places an extra load on each crew. When conducting multiship operations into a small LZ, the pathfinder
controller should allow sufficient time between liftoff and landing for the turbulent air generated during the
departure of the previous helicopter to stabilize. Otherwise, the pilot of the incoming craft will experience
that turbulence and lose lift.
4-122. A pilot must touch down very carefully on the typical small, rough, sloped mountain LZ.
Depending on the angle of the slope and on the aircraft's available torque, the pilot might be able to make a
normal slope landing. Pilots of larger craft, such as cargo helicopters, might have trouble positioning the
entire fuselage in the available area. Once the cockpit extends over the landing area, the pilot cannot see
the ground. He must rely on the crew chief and signalman to direct him.
4-123. During a mountain approach to an LZ surrounded by uneven terrain, the pilot has a hard time
determining the actual aircraft altitude and rate of closure. Where the terrain slopes up to the LZ, a visual
illusion occurs. The pilot might think he is flying too high and closing too slowly. If the terrain slopes
down to the LZ, he might feel he is flying too low and closing too fast. Employing a signalman on the
ground gives the pilot a visual reference to adjust his controls. He might need more than one signalman.
SITE ASSESSMENT
4-124. Pathfinders should determine the following information while reconnoitering and selecting a
mountain site:
y The size, slope, amount of surface debris, and the area covered by shadows and obstacles in and
around the site.
y The approximate direction, speed, and characteristics of the wind.
y The inbound route, if necessary. When the pilot cannot land due to a steep slope, the aircraft
might terminate at a hover to off-load troops and supplies.
y The departure route. Departure routes should orient into the wind and over the lowest obstacles.
SECTION VII. APPROACH PATH CONSIDERATIONS
Pilots should try to land their aircraft into the wind; however, the terrain and its effect on the wind might
require a crosswind landing. If so, the pilot for single-rotor helicopters should plan the approach so that the
wind blows from the left side of the aircraft. This helps the pilot overcome the effects of torque, reduces power
requirements, and helps him control the heading. Other considerations include vertical air currents, escape
routes, terrain contour and obstacles, and the position of the sun. |
3-21.38 | 84 | Chapter 4
VERTICAL AIR CURRENTS
4-125. Updrafts on the approach path make landing easier. However, severe vertical air currents (updrafts
or downdrafts) might require the pilot to approach downwind.
ESCAPE ROUTES
4-126. The pathfinders and pilots should plan one or more escape routes along the approach path for the
pilot to use if he must go around and try the approach again.
TERRAIN CONTOUR AND OBSTACLES
4-127. The height of terrain and obstacles along the approach path should permit the pilot to conduct a
shallow approach angle into the landing site. When possible, the pathfinders select a landing point on or
near the highest terrain feature.
POSITION OF THE SUN
4-128. Though the pilot first considers wind direction and nature of the terrain when choosing the
approach path, he must also consider the relative location of the sun and shade. To keep the pilot from
having to adjust from one light condition to another, the pathfinder makes sure that if the landing point
falls in a shaded spot, the whole approach path does as well. When the sun rises or falls to just above the
horizon, avoid using an approach path that faces directly into it. |
3-21.38 | 85 | Chapter 5
External Loads
Carrying cargo and equipment outside the helicopter eliminates many of the
problems that other modes of transportation have. Helicopters move cargo by
external slingload when—
y The cargo compartment cannot hold the load.
y The load exceeds the helicopter's internal load limitation.
y The ground crew must load or unload the cargo at once.
y Landing zone conditions prevent the aircraft from touching down.
Pathfinder-qualified Soldiers prepare to organize and control external load pickup or
drop-off sites as an integral part of LZ operations. The supported unit provides a
detailed load plan, to include rough weights and sequences of load movement. This
ensures the correct and rapid movement and placement of cargo.
LANDING POINTS
5-1. Conditions such as a dusty surfaces, darkness, or obstacles often require pathfinders to increase
the minimum spacing between loads and landing points. This reduces the number of helicopters that can
safely operate at the site at the same time, the size of the mission that can be supported, and the overall
speed of the operation.
TYPES OF LOADS
5-2. All external loads fall under one of three types: high density, low density, or aerodynamic. Each
exhibits unique characteristics in flight. Pathfinders determine the type, size, and weight of the load during
the planning phase of the operation.
HIGH DENSITY
5-3. The high-density load offers the best stability.
LOW DENSITY
5-4. The low-density load offers the least stability.
AERODYNAMIC
5-5. The aerodynamic load lacks stability until the airstream stabilizes the load. The ACL depends on
the type of aircraft, the age of the airframe, the altitude above sea level, the temperature, the humidity, and
the aviation unit's SOP. |
3-21.38 | 86 | Chapter 5
UNIT RESPONSIBILITIES
5-6. Most slingload operations involve four units. Each has pathfinders who perform specific
functions.
SUPPORTED UNIT
5-7. The supported unit moves equipment and rigs the loads. Pathfinders in the supported unit check
the weight, rigging, and positioning of all external loads to ensure helicopter safety. Ideally, the supported
unit provides hookup personnel for individual loads. In the supported unit, pathfinders assist in—
y Selecting, preparing, and controlling the PZ.
y Coordinating in advance with the supporting unit.
y Rigging the loads.
y Furnishing slings, straps, clevises, and any other slingload equipment required for the move.
y Checking for improper rigging and weight in excess of the aircraft's ACL.
AVIATION UNIT
5-8. This is the aviation unit that will fly the loads. They—
y Provide advice and technical help to the supported unit, as required.
y Ensure that the loads fall within the transporting aircraft's ACL.
y Provide assistance in the recovery and return of slingload equipment.
y Advise the supported unit on load limitations.
y Advise the supported and receiving units on the suitability of selected LZs and PZs.
y Establish coordination with the supported and receiving units.
RECEIVING UNIT
5-9. The receiving unit—
y Selects, prepares, and controls the LZ.
y Provides trained ground crews to guide the aircraft and de-rig the loads.
y Coordinates with the supporting unit for the control and return of the slingload equipment.
y Inspects the rigging of back loads.
PATHFINDER UNIT
5-10. In the pathfinder unit, pathfinders—
y Provide advice and aid to the supported, aviation, and receiving units.
y Provide expertise in the planning and execution of both PZ and HLZ operations.
y Supervise the rigging and inspection of all the loads.
y Provide ground guidance and air traffic control during the slingload.
y Ensure that the loads fall under the transporting aircraft's ACL.
EQUIPMENT
5-11. Cargo nets and slings make up an essential part of the external load operation. During an
inspection, they require the same level of attention that the cargo receives. Any evidence of frayed or cut
webbing justifies replacement of the affected component. When they assemble slings, pathfinders should
avoid sewing up torn slings or substituting nonstandard parts in the field. Slings must meet the critical |
3-21.38 | 87 | External Loads
strength requirements specified in FM 10-450-3. The Army's inventory includes a variety of equipment
adapted or designated for use in slingload operations.
AERIAL-DELIVERY SLINGS
5-12. Aerial-delivery slings (ADSs) were originally designed to deliver heavy loads by air (Table 5-1).
They have been adapted for use in air assault operations. ADSs come in a variety of sizes and strengths, as
shown in FM 10-450-3.
Vertical Pendant Available Lengths
Usage Loop Slings Pounds Thicknesses (In Feet)
3 feet 16 feet
2-Loop 1,2 8,900 4 9 feet 20 feet
11 feet
120 feet
12 feet
3-Loop 13,500 6 60 feet 140 feet
Pendant 3 feet 16 feet
9 feet 20 feet
4-Loop 17,800 8
11 feet 28 feet
12 feet
6-Loop 27,000
12 60 feet 120 feet
9-Loop 42,000
3 feet 16 feet
2-Loop 1,2 5,600 4 9 feet 20 feet
11 feet 120 feet
3-Loop 8,500 6 60 feet 140 feet
Part of
sling set 3 feet 16 feet
9 feet 20 feet
4-Loop 11,200 8
11 feet 28 feet
12 feet
6-Loop 17,000 12 60 feet 120 feet
1
Identified by colored thread stitched lengthwise down the middle of the strap.
2
Three-foot donut ring tensile strength for this sling equals 10,000 pounds. Using dual rings increases
tensile strength to 17,500 pounds.
Table 5-1. Aerial delivery specifications for the Type XXVI sling. |
3-21.38 | 88 | Chapter 5
HITCHES
5-13. When connecting ADSs to metal air items or directly to the load, loaders use one of the following
hitches (Figure 5-1).
Choker
5-14. Pull the free-running end of the sling around the point of attachment. Draw it between the loops of
the sling's standing end. After making sure that the cotton buffer is in its proper place, "milk" down the
keeper on the standing end to secure the sling.
Basket
5-15. Separate the loops of the sling at one end. Place the sling over the suspension point. Ensure that
the cotton buffer is in its proper place. To secure the sling, "milk" down the keeper towards the
suspension point.
Figure 5-1. Hitches.
NETS AND CONTAINERS
5-16. The Army has many types of cargo containers. However, the 5,000- and 10,000-pound cargo nets
and the A-22 cargo bag are the ones most often used to transport cargo externally. FM 10-450-3 describes
how to inspect both the large cargo net and the A-22 cargo bag (Figure 5-2). It also provides rigging
instructions. Avoid overloading the nets; use them with loads that fall within the aviation unit's prescribed
limits. Pick up the nets rather than drag them across the ground, because dragging them can cause them to
snag on something and damage the net or the thing it snags. Use a canvas insert when carrying items small
enough to slip through the netting.
Small (5,000-Pound Capacity) Cargo Net
5-17. This olive drab net can carry up to 5,000 pounds or 125 cubic feet of cargo (NSN
1670-01-058-3811, line item number [LIN] 2776).
Large (10,000-Pound Capacity) Cargo Net
5-18. This larger net can carry up to 10,000 pounds or 380 cubic feet of cargo (NSN 1670-01-058-3810,
LIN NO 2708). It is 18 feet wide and can transport boxed or bulky loads (Figure 5-2). |
3-21.38 | 89 | External Loads
Figure 5-2. Cargo nets and bag.
A-22 Cargo Bag
5-19. The A-22 cargo bag, with or without its canvas cover, can externally transport standard palletized
loads, loose cargo, ammunition, oil drums, and other general items whose total weight falls under 2,200
pounds (Figure 5-3).
Figure 5-3. A-22 cargo bag. |
3-21.38 | 90 | Chapter 5
Suspension Clevises
5-20. Clevises come in three sizes.
Large
5-21. This clevis (NSN 4030-00-090-5354) has a rated capacity of 12,500 pounds (pendant) with a
7,875-pound sling-to-lifting provision point of attachment. Adding more large clevises as attaching points
increases rated capacity as follows:
y Two large clevises increase rated capacity to 15,750 pounds.
y Three large clevises increase rated capacity to 23,625 pounds.
y Four large clevises increase rated capacity to 31,500 pounds.
Medium
5-22. This clevis (NSN 1670 4030-00-678-8562, Figure 5-4) has a rated capacity of 6,250 pounds
(pendant) with a 3,750-pound sling-to-lifting provision. Adding more medium clevises as attaching points
increases rated capacity as follows:
y Two medium clevises increase rated capacity to 7,500 pounds.
y Three medium clevises increase rated capacity to 11,250 pounds.
y Four medium clevises increase rated capacity to 15,000 pounds.
Figure 5-4. Upper sling and medium clevis. |
3-21.38 | 91 | External Loads
Small
5-23. This clevis (NSN 1670 4030-00-360-0304) has a rated capacity of 6,250 pounds (pendant) with a
3,750-pound sling-to-lifting provision. Adding more small clevises as attaching points increases rated
capacity as follows:
y Two small clevises increase rated capacity to 7,500 pounds.
y Three small clevises increase rated capacity to 11,250 pounds.
y Four small clevises increase rated capacity to 15,000 pounds.
REACH PENDANTS
5-24. A reach pendant is a synthetic rope assembly with an attached, stiffened reach tube and a loop on
each end. The built-in reach tube enables the hookup man to place the pendant's top eye on the helicopter
cargo hook while the helicopter hovers at a higher distance over the load (Figure 5-5). Two reach pendants
are authorized for use with slingloads. To use either pendant with a sling set, remove the sling set apex
fitting pin; place the pendant's lower eye in the apex fitting; and reinstall the apex fitting pin.
11,000-Pound Capacity
5-25. The 11K, NSN 4020-01-365-3115, part number DSG-5-11K, measures about 5 feet long and has
an 11,000-pound safe working load capacity. The top eye is black with a small diameter loop, while the
bottom eye is green with a larger diameter loop. The safe working load capacity is stamped on the
reach tube.
25,000-Pound Capacity
5-26. The 25K, NSN 4020-01-337-3185, part number BOS-14-K7, measures about 5 feet long and has
a 25,000-pound safe working load capacity. The top eye is black with a small diameter loop, while the
bottom eye is also black, but has a larger diameter loop. The safe working load capacity is stamped on the
reach tube.
Figure 5-5. Reach pendant. |
3-21.38 | 92 | Chapter 5
Inspection
5-27. Inspect the reach pendants before and after use. Check for cuts and tears in the nylon-urethane
plastic sheath on each loop. If the white strength member (third layer) shows, remove the pendant
from service.
Cleaning
5-28. Clean the reach pendant with a mixture of warm water and mild dish or laundry detergent. You
can use mineral spirits to remove oil and grease. You can treat the top and bottom eyes with silicone spray.
However, do not use silicone spray on the reach tube.
Storage
5-29. Store the reach pendants in a clean, dry area out of direct sunlight. Prolonged exposure to sunlight
will deteriorate the strength of reach pendants.
CAUTION
Avoid getting silicone spray on the reach tube. Avoid using chemical
cleaners on reach pendants. Chemicals may weaken the strength
members of the pendant. If a pendant becomes contaminated with
chemicals, remove it from service.
POLYESTER ROUNDSLINGS
5-30. Use polyester roundslings as the primary vertical pendant (Figure 5-6). You can use one of three
hitches to attach roundslings to the load. The lifting capacity of polyester roundslings varies with the size
of the sling and the type of hitch used to attach the load. Each sling has two identification tags permanently
sewn to the eye and eye sleeve. These identify the size and capacity of the roundsling as well as other
information needed for its safe use. Roundslings are also color-coded by size. Table 5-2 lists roundsling
lengths and lift capacities.
Storage
5-31. Store roundslings in a clean, dry, cool area out of direct sunlight. Prolonged exposure to sunlight
will deteriorate the strength of roundslings.
Inspection
5-32. Inspect each polyester roundsling before and after every use. Remove it from service if you find
any of the following:
y Missing or unreadable identification tags.
y Acid or alkali burns.
y Melted, charred, or weld-splattered portions.
y Any holes, tears, cuts, snags, embedded particles, broken or worn stitching, or abrasive wear
that exposes the core fibers.
y Knots in any part of the roundsling.
y Distortion, excessive pitting, corrosion, or broken fitting(s).
y Any other condition that causes doubt as to the strength of the roundsling. |
3-21.38 | 93 | External Loads
CAUTION
Avoid dragging roundslings on the floor or over rough surfaces. Never
twist them or join them together with knots.
Figure 5-6. Polyester roundslings.
Length Lift Capacity Weight
Part No. (In Feet) Color (In Pounds)
Choke Vertical Basket
PRS2E008 8 GREEN 4,200 5,300 10,600 4
PRS2E017 17 GREEN 4,200 5,300 10,600 10
PRS3E008 8 YELLOW 6,700 8,400 16,800 5
PRS3E017 17 YELLOW 6,700 8,400 16,800 11
PRS5E030 30 RED 10,600 13,200 26,400 26
PRS7E065 65 BLUE 17,000 21,200 42,400 75
PRS7E070 70 BLUE 17,000 21,200 42,400 81
Table 5-2. Safe working loads (lift capacities) of polyester roundslings. |
3-21.38 | 94 | Chapter 5
SERVICE LIFE OF AERIAL-DELIVERY SLINGS
5-33. The first person to use a sling must date-stamp it with the calendar or Julian date in
1-inch letters. He can use orange-yellow parachute-marking ink, strata blue parachute-marking ink, or an
orange-yellow tube-type marker. He marks near the first keeper at both ends of the sling. This date
determines the date of the next inspection. Every six months, the current user reinspects the sling; strikes
through the last date in the same color it was written in; and in either of the other two colors, marks the
date he reinspected the sling. Every single user inspects every single sling before and after every single use.
If the condition of the sling seems questionable, he removes the sling from service (Figure 5-7).
Figure 5-7. Unserviceable slings.
GENERAL INSPECTION
5-34. When inspecting nylon air items, note that if you find more than three consecutive broken or loose
stitches, or five or more broken or loose stitches overall in the sewn portion, the item is unserviceable.
After rigging the load with any nylon air item, put cotton buffers in place to prevent any nylon-to-nylon or
nylon-to-metal contact. Look for the following:
y Inspection date that has already passed (an inspection is overdue).
y Foreign matter or chemicals such as mildew, paint, or grease.
y Cuts.
y Frays.
y Burns.
y Broken stitches.
y Missing cotton buffers, sliding keepers, or permanent keepers.
y Rust.
CARGO STRAP
5-35. The A7A cotton or nylon cargo strap measures 188 inches long and has a rated capacity of 500
pounds. A friction adapter located on one end of the strap has a thick-lipped metal floating bar. Supply
issues this strap with one metal D-ring. Inspect this piece of equipment for cuts or frays. |
3-21.38 | 95 | External Loads
CARGO TIE-DOWN EQUIPMENT
5-36. Check the tie-downs for serviceability.
CGU-1B Tie-Down Strap
5-37. The CGU-1B cargo tie-down device has a rated capacity of 5,000 pounds. You can adjust the
length of this device.
15-Foot Tie-Down Strap
5-38. The 15-foot cargo tie-down strap, issued with a quick-fit strap fastener, has a rated capacity of
5,000 pounds.
Load Binders
5-39. The two load binder types are rated for 10,000 pounds and 5,000 pounds. The 10,000-pound
capacity load binder has its rating stamped on the side.
METAL AIR ITEMS
5-40. Thoroughly inspect metal air items for rust, stripped threads on the nuts or bolts, burrs, cracks,
bent or twisted metal, or oil. When using any clevis assembly, tighten the nut hand-tight only.
Inspection
5-41. Use the Type IV link assembly (NSN 1670-00-783-5988) to build a 3-foot donut or to connect
one ADS to another (Figure 5-8). This link assembly has a rated capacity of 12,500 pounds. When
inspecting the Type IV link assembly, look for the following deficiencies:
y Hard to rotate or irregularly rotating aluminum buffers.
y Bent or cracked posts.
y Bent slide connectors.
y The absence of a metallic "click" when it locks.
Figure 5-8. Three-foot apex (donut) ring. |
3-21.38 | 96 | Chapter 5
Points of Attachment
5-42. In slingload operations, the clevis assemblies serve as points of attachment from the aircraft to
the load.
Tightening
5-43. When using any clevis assembly, tighten the nut by hand only. Tape both ends of the nut and bolt
to prevent slippage during use. Choose only case-hardened nuts and bolts. Never mix items. The bolt heads
have case-hardened marks such as ticks, numbers, letters, or a combination of all three.
LARGE-CAPACITY SLING SETS
5-44. The new 10,000-pound and 25,000-pound capacity sling sets are similar, except for a few minor
differences. All components have identifying marks. You may only exchange apex fittings between sets.
Take care not to mix up the other components. Table 5-3 compares these two large-capacity sling sets, and
Figure 5-9 shows one.
Type Sling 10,000-Pound Sling 25,000-Pound Sling
Capacity: 10,000 pounds 25,000 pounds
Color: Brushed aluminum Gold steel
Apex fitting Pin diameter: 1 1/8-inch diameter 1 1/2-inch diameter
Weight: 4 1/2 pounds 10 pounds
Color: Olive drab Black
Sling rope Length: 12 feet 12 feet
Diameter: 7/8 inch 1 1/4 inch
Chain links-quantity: 110 to 115 links 86 to 88 links
NSN: 1670-01-027-2902 1670-01-027-2900
Total weight: 52 pounds 114 pounds
Table 5-3. Large-capacity sling sets.
Figure 5-9. 25,000-pound capacity sling set. |
3-21.38 | 97 | External Loads
CAUTION
Each sling set has four legs. Each leg has a rated capacity of
one-quarter of the total capacity of the set. On some loads, you will
use up to six legs. However, remember that adding two legs does not
increase the rated capacity of the entire set.
5-45. The nylon rope assembly for each set has an interwoven eye located at each end. A polyurethane
fitting covers the eye to protect the leg from abrasion and ultraviolet radiation (Figure 5-9). Each
double-braided rope connects to a grabhook assembly. Figure 5-10, Figure 5-11, and Figure 5-12 show a
coupling link, sling leg-numbering sequence, and a grabhook, respectively. Though the grabhooks for the
two sets look alike, you cannot interchange them because they have different ratings.
5-46. FM 10-450-3 and TM 10-1670-295-23&P discuss how to inspect the rope sling sets.
FM 10-450-3 also provides sling-conversion tables.
5-47. Secure the cross pin on each apex fitting with a 3/8-inch bolt, a castellated nut, and a cotter pin.
Figure 5-10. Coupling link.
Figure 5-11. Sling leg-numbering sequence. |
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Figure 5-12. Grabhook. |
3-21.38 | 99 | External Loads
AIRCRAFT LOAD LIMITATIONS
5-48. The structural strength of the cargo hook assembly determines the maximum weight that any
aircraft can carry with an external slingload. In most cases, the tensile strength of the hook does not limit
the weight that an aircraft can lift; the allowable cargo load does. In fact, the capacity of the cargo hook
assembly usually exceeds the ACL.
TENSILE STRENGTH
5-49. Cargo hook tensile strengths for US Army aircraft show—
y UH-1H/UH-1N Iroquois – 4,000 or 5,000 pounds (Figure 5-13).
y UH-60A/60L Blackhawks – 8,000 or 9,000 pounds (Figure 5-14).
y CH-47D Chinook – 26,000 pounds (Figure 5-15, page 5-18).
Figure 5-13. UH-1H Iroquois and its cargo hook. |
3-21.38 | 100 | Chapter 5
Figure 5-14. UH-60 Blackhawk and its cargo hooks. |
3-21.38 | 101 | External Loads
Figure 5-15. CH-47 Chinook and its cargo hooks. |
3-21.38 | 102 | Chapter 5
UH-1H
5-50. When transporting external loads with a UH-1H, use a nylon donut or web ring to attach the load
to the aircraft. The cargo hook on the UH-1H is stationary; using an apex with a heavy load would bind the
hook and shear it off. The cargo hook tensile strengths for the UH-1H is 4,000 pounds; for the UH-1N, it is
5,000 pounds.
UH-60 BLACKHAWK
5-51. When using the 10,000-pound apex to secure an external load to the UH-60, you must also use the
aluminum spacer. The spacer is not required, or recommended, when using a 25,000-pound apex.
However, if you use the 25,000-pound apex with spacer, the cargo hook must be manually operated by an
aircraft crewmember or a member of the hook-up team. Never use a donut or web ring on a UH-60. The
web ring will bind on the hook and prevent the crew from releasing the load in an emergency. The tensile
strength of the UH-60 cargo hook system is, for the UH-60A, 8,000 pounds and for the UH-60L,
9,000 pounds.
STANDARD WEIGHTS
5-52. When using a UH-60 Blackhawk for airlift, coordinate closely with the aviation unit for the ACL.
For the standard weights of petroleum, oils, and lubricants (POL), for external loads only, see Table 5-4.
Standard vehicle and artillery weights follow in Table 5-5 and Table 5-6.
Fuel 55-Gallon Drum 500-Gallon Blivet
Motor gasoline (MOGAS) 404 pounds 3,400 pounds
Gasoline (JP4/JP8) 410 pounds 3,500 pounds
Diesel fuel 457 pounds 3,800 pounds
Lube oil (30 weight) 479 pounds 4,000 pounds
Table 5-4. POL for external loads only. |
3-21.38 | 103 | External Loads
Vehicle Weight
M998/M1038 Truck, Cargo, 5,200 pounds (empty)
1 1/4-ton (HMMWV) 7,700 pounds (loaded)
M966 TOW Missile Carrier (HMMWV) 6,050 pounds (empty)
8,200 pounds (loaded)
M416 1/4-Ton Trailer 580 pounds
M101A2 3/4-Ton Trailer 1,350 pounds
M105A2 1 1/2-Ton Trailer 2,750 pounds
M35A2 2 1/2-Ton Truck 12,000 pounds (add 500 pounds
if equipped with a winch)
M149 1 1/4-Ton Water Trailer 2,540 pounds (empty)
6,060 pounds (full)
M149A1 1 1/4-Ton Water Trailer 2,540 pounds (empty)
6,060 pounds (full)
M149A2 1 1/4-Ton Water Trailer 2,800 pounds (empty)
6,320 pounds (full)
Table 5-5. Standard vehicle weights.
Artillery Weight
M101 105-mm howitzer 4,600 pounds (add 300 pounds if
equipped with shields)
M102 105-mm howitzer 3,160 pounds (add 170 pounds for
section equipment)
105-mm ammunition 60 pounds (each box)
105-mm ammunition 47 pounds (each carton)
Table 5-6. Standard artillery weights.
AIR ITEMS REQUIRED FOR COMMON STANDARD LOADS
5-53. Pathfinders require several types of expendable rigging supplies to complete the rigging of the
loads discussed in this paragraph. These supplies include 1/4-inch cotton webbing (80-pound test),
3/8-inch diameter rope (3,180-pound test), 7/16-inch diameter nylon rope (4,500-pound test), type III
nylon cord (550-pound test), pressure-sensitive tape, cellulose wadding or paperboard energy-dissipating
material, and canvas or felt padding. Pathfinders should obtain sufficient supplies of these items before
rigging the loads. To rig loads with ADSs and with more than one suspension point, twist an ADS once for
each 3 feet of sling length. This reduces vibration in the sling during flight. The nylon and chain multileg
sling sets and the 10,000- and 25,000-pound capacity sling sets do not require the twists. FM 10-450-3
discusses preparation and rigging for the following loads in detail. |
3-21.38 | 104 | Chapter 5
CARGO NET
5-54. A 5,000-pound-capacity (15 feet square) or 10,000-pound-capacity (18 feet square) nylon cargo
net requires one A7A cargo strap or length of rope. With this the pathfinder can secure the net together on
top of the load to prevent smaller items from falling out of the net.
PERFORATED STEEL PLANKING
5-55. Perforated steel planking (PSP) requires—
y Two 16-foot, two or three-loop ADSs.
y One 3-foot ADS with one type IV link assembly (for donut).
FUEL DRUMS
5-56. One or two rubber or fabric fuel drums (blivets), each of which contains 500 gallons of fuel and a
10,000-pound-capacity sling set.
CONCERTINA WIRE
5-57. The items required to move this load depend on the amount of concertina wire in the load.
CARGO BAG
5-58. The A-22 cargo bag has a maximum capacity of 2,200 pounds.
SLINGLOAD THEORY
5-59. The behavior of an external load in flight can greatly affect the performance of the aircraft
carrying it. High drag coefficients reduce airspeed. This means that the task takes longer or does not get
finished if the allotted time for the task expires. Therefore, whoever prepares the load must try to reduce
the drag of the load on the aircraft. A high drag coefficient can also endanger the aircraft and crew.
Because of this, the pilot must "punch" if he thinks that continuing to fly the load could endanger his crew
or aircraft. To stabilize a load, the loaders should consider the following:
ADDITION OF WEIGHT TO THE LOAD
5-60. The heavier a load, the less air pressure will disturb it. Thus, carrying heavier loads assures greater
stability. However, make sure the load does not exceed the rated capacity of the equipment or the ACL of
the aircraft.
STREAMLINING OF THE LOAD
5-61. Long, symmetrical loads fly crosswise to the direction of flight. This causes a lot of drag on the
aircraft. Loads tend to stabilize if the center of gravity (CG) is located in the first one-third of the load.
Either adjust the load or, if needed, add weight to move the CG toward one end or the other. The heavier
end of the load will "seek" the direction of flight and the load will stabilize. The lighter tail end of the load
will act just like the fins on a dart.
AIRSPEED OF THE AIRCRAFT
5-62. The least desirable method is to have the aircraft fly slow to try to keep the load from
destabilizing. This burns extra fuel and takes more time to do less work. Prepare the loads so that the
aircraft can fly safely at speeds of 60 knots or more. |
3-21.38 | 105 | External Loads
SLING LENGTH
5-63. Lengthening the slings that attach the load to the aircraft reduces the load's stability in flight. The
shorter, the better, as long as the sling measures at least 6 feet long. Also, the more vertical the attached
sling, the less stress on those that are more horizontal. Figure 5-16, page 5-22, shows how sling angle
affects load stress.
Figure 5-16. Load chart of sling tension at various angles of inclination with a load
of 1,000 pounds.
EFFECT OF VERTICAL SLING
5-64. A vertical sling carrying 3,000 pounds has 3,000 pounds of stress on it. That means the stress
equals the weight of the load.
EFFECT OF 45-DEGREE SLING
5-65. A 45-degree sling carrying 3,000 pounds has 4,242 pounds of stress on it. That means the stress
equals nearly one-and-a-half times the weight of the load.
EFFECT OF 5-DEGREE SLING
5-66. A 5-degree (almost horizontal) sling carrying 3,000 pounds has 34,419 pounds of stress on it.
That means the stress equals more than ten times the weight of the load.
HOOKUP AND RELEASE PROCEDURES
5-67. Hooking up a load requires a team effort. The signalman must position the aircraft over the load.
He does this so the slingload team can discharge the static electricity and attach the load to the aircraft as
quickly and safely as possible. Most of the time, the air crew releases the load. This seldom requires any
ground crew except the signalman. |
3-21.38 | 106 | Chapter 5
GROUND CREW PROTECTIVE MEASURES AND EQUIPMENT
5-68. Working around hovering helicopters exposes ground crews to a variety of dangers. Leaders must
do everything they can to ensure the safety of the ground crews. The crews themselves should use the
following safety equipment (Figure 5-17).
Helmet
5-69. This protects the wearer from head injuries caused by flying debris. It also protects him if his head
were to get caught between the aircraft and the load, for example. Wearers must keep helmets securely
fastened. |
3-21.38 | 107 | External Loads
Figure 5-17. Protective equipment. |
3-21.38 | 108 | Chapter 5
Protective Mask or Dust Goggles with Respirator
5-70. In high dust or debris environments, each crewmember wears a mask or goggles. This protects the
crewmembers' faces, eyes, and respiratory systems from the airborne particles stirred up by the rotor wash.
The mask protects better than the goggles but can cause problems with depth perception (important for
signalmen).
Earplugs or Suitable Substitute
5-71. These protect against the excessive noise associated with hovering aircraft. They also prevent
debris from entering the ear canal.
Hand Protection
5-72. Marine Corps and Navy personnel must wear gloves designed to protect electrical workers against
burns due to static discharges. Everyone else (US Army, USAF, and USCG) should wear leather gloves to
help protect the hands and fingers. Whoever must use the static wand to discharge static electricity should
wear gloves designed for adequate protection from static discharge burns.
y Inspect shockproof gloves before and after each operation. Check for excessive wear, fraying,
holes, and tears. Do not use a torn glove. Even a small hole leaves a person unprotected from
static electric shock.
y Check each glove for holes by filling it with water and squeezing it while holding the open end
closed. Or, blow air into it like a balloon and submerge it in water. Any holes will cause air
bubbles.
Static Discharge Wand
5-73. The static discharge wand protects the hookup man from electrical shock by grounding the cargo
hook. In flight, the helicopter stores static electricity. This electrical charge increases with the weight of the
helicopter, with low humidity, and with the amount of debris blown around by the rotor system (dust, sand,
or snow). Thunderstorms can cause huge discharges of static electricity. When the helicopter lands and
touches the ground, this charge grounds. However, while the helicopter remains airborne, such as when it
hovers to make a slingload drop, the charge stays in the aircraft. As soon as the ground-crew member
connects the apex fitting to the cargo hook, he becomes a path for an electrical charge to follow into the
ground. This charge can cause severe electrical burn or injury.
y To avoid the possibility of a static electric shock, ground the cargo hook (connect the helicopter
to the ground) using grounding stakes and static discharge wands. (The stakes and wands may
be field-expedient or manufactured.) Because these wands connect the helicopter to the ground,
the electric charge dissipates. This protects the hookup man from receiving a shock when he
connects the apex fitting to the cargo hook.
y Inspect the static discharge wand to make sure it is in serviceable condition. Drive the
grounding stake opposite the ground crew's exit direction. This keeps them from tripping on the
cable as they leave.
y Drive the stake into the ground until it seats firmly—at least 6 to 8 inches in firm ground and
24 inches in sandy or loose soil. Drive the stake in at a 45-degree angle away from the side of
the load, in case someone falls on it. Connect the cable clamp to the vertical shaft of the stake.
y When operating on concrete or asphalt surfaces, position the loads as close to the edge of the
surface as you can. This allows you to drive the grounding stake into the ground.
y Do not hold the static discharge wand within 14 to 16 inches of the metal hook end—a strong
static charge can jump as far as 12 inches. During the hookup operation, the static discharge
wand must stay in contact with the cargo hook. If contact fails, all ground-crew members must
pull back from the hook until someone can reestablish contact between the wand and the
aircraft's cargo hook. |
3-21.38 | 109 | External Loads
Other Equipment
5-74. Use smoke grenades to mark the location of the landing site or to indicate wind direction. Use
flashlights with wands to give arm-and-hand signals at night.
SAFETY
5-75. In addition to using the proper equipment, Soldiers must also follow these other safety measures:
y Wear long-sleeved shirts with the sleeves rolled down and fastened. Button your shirt collar.
Tuck shirttails or jacket bottoms into your trousers.
y Police the operational area thoroughly before conducting slingload operations. This cuts down
on the amount of debris thrown about by rotor wash.
5-76. Stay alert during hookup and release operations; sound judgment and common sense hold the keys
to success. Stay ready to get clear of the load. Soldiers have been crushed between the aircraft and loads.
Some have had loads dragged over them; others took an unwanted ride when they somehow entangled
themselves with the load. Whenever you have to make the hookup, take special care. Slings under tension
can easily crush an arm or leg against the load. Some of the particular hazards associated with loads
include—
Cargo Extensions or Projections
5-77. Gun tubes, landing gear, missile launchers, bridge planks, and so forth can interfere with or injure
you by striking or tripping you. Stand clear of such projections or position yourself so you can clear the
load at once.
Sharp Projections, Hooks, Handles, Racks
5-78. If possible, avoid these. Examples include protruding handles or levers such as tarpaulin tie-down
hooks, door handles, spare-tire racks, and similar projections. Sharp edges can cause serious injury. You
can quickly get hooked to the load if your clothing or equipment catches on something. Keep alert and
ready to move out of danger immediately.
Top-Heavy or Narrow-Based Loads
5-79. Treat with caution any top-heavy or narrow-based loads that the rotor wash could blow over. If
possible, lay this kind of load on its side before starting the hookup. If you cannot do this, position the
crew on the side or end of the load that is least likely to tip. Again, stay ready to move away from the
danger quickly.
High Loads
5-80. High loads can seriously injure you if you climb up on them to hook them up. Rotor wash can
sweep you off, or you might have to jump to avoid a dangerous situation. Pay attention to where you stand.
Try to stand on a lower projection or step rather than on top of the load. This way, if the aircraft makes
contact with the load, it does not catch you in between. Also, try to work from a crouched position or from
your hands and knees. Keep solid footholds and handholds, and stay ready to move quickly out of the way
if you need to. If possible, back a vehicle up to the load and use it as a working platform. (Move it out of
the way before the aircraft starts to lift the load.)
GROUND CREW EMERGENCY CONDUCT
5-81. When an aircraft hovering over a slingload suffers an emergency severe enough for the pilot to
have to set the aircraft down, he will do so. This can happen all at once such as in a controlled crash. For |
3-21.38 | 110 | Chapter 5
this reason, whenever an aircraft seems to be having trouble, all members of the ground crew should clear
the slingload point by moving to a location coordinated with the aviation unit. Once they have moved far
enough away, they should each take a prone position or seek cover until the aircraft lands. Two
responsibilities require special note:
Signalman
5-82. Face the aircraft; move to a safe spot.
Hookup Men
5-83. Try to work along the same side of the load as your assembly area, or as coordinated. This way,
you do not have to climb over or go around the load to seek safety. You can instead move directly off and
away from the load. If the load is a heavy piece of equipment, you might want to keep the load between
you and the aircraft while you are moving. This offers you some protection if the aircraft were to crash.
GROUND CREW DUTIES
5-84. Normally, the ground crew consists of one signalman and two hookup men, with one hookup man
acting as static wand man.
Signalman
5-85. Duties of the signalman include the following.
Before the Aircraft Arrive(s)
5-86. Direct the positioning of the load. Supervise the inspection of the load for proper routing of the
slings and proper preparation. Ensure that the load is ready to fly.
As the Helicopter(s) Approaches
5-87. Station yourself 20 meters in front of the load where you can best maintain eye contact with the
crew. Give the arm-and-hand signal of "assume guidance." As the helicopter nears the load, use
arm-and-hand signals to position the cargo hook directly over the load, close enough that the hookup men
can place the apex fitting onto the cargo hook. During this time, position yourself so the pilot can see your
signals easily. Because the pilot of an Army aircraft sits on the right side of the aircraft, you will usually
stand just to the right of the aircraft. If the terrain forces you to stand somewhere else, make sure the pilot
can see you at all times.
During the Hookup Process
5-88. Watch the cargo hook and apex fitting. After hookup, the pilot hovers the aircraft until the hookup
men clear away from the load. When they have moved clear, you will signal the aircraft upward slowly, so
the sling legs gradually take up the load. You must do this to make sure the sling legs clear the load. If the
sling legs foul, motion the pilot downward, and then instruct him to cut away the load. If you did a good
job of hooking up the load, and if the load suspends properly below the aircraft, then give the aircraft the
signal to depart. Then move quickly aside to clear the helicopter's path. |
3-21.38 | 111 | External Loads
DANGER
AT NO TIME WILL THE SIGNALMAN OR ANY OTHER MEMBER
OF THE SLINGLOAD TEAM ALLOW A SUSPENDED LOAD TO
PASS OVER HIS HEAD.
Hookup Men
5-89. Duties of the hookup men include the following:
y One of you handles the static discharge wand and the cargo hook. The other controls the apex
fitting of the slingload. Together, you must complete the hookup fast to reduce helicopter hover
time and to reduce your exposure time under the helicopter.
y Position yourselves by the load so that, while the helicopter hovers over the load, you can
quickly complete the hookup (Figure 5-18). You must also make sure the signalman can
continually observe the operation.
y When the helicopter moves into the correct position for hookup, whichever one of you is the
static wand man must ground the aircraft. Touch the static wand to the cargo hook
(Figure 5-19, page 5-28) and keep it there to maintain a continuous ground.
Figure 5-18. Position of hookup team. |
3-21.38 | 112 | Chapter 5
Figure 5-19. Grounding technique.
y Once the static wand man grounds the aircraft, the other hookup man places the apex fitting
onto the cargo hook, then checks to make sure that the hook is properly closed (and locked, if
required).
y After you properly hook up the load to the aircraft, both of you must move quickly aside to the
location coordinated with the aviation unit. If the signalman learns that any of the legs have
fouled, he notifies the pilot at once. Also, you will have to rehook the load.
RELEASE PROCEDURES
5-90. For this mission, leaders refer to the hookup men as the "cargo release team." As the helicopter
approaches the site, the pilot takes instructions from the signalman, who guides the aircraft into position for
cargo release. The cargo release team stands by, unless it must release the load manually. The signalman
directs the aircraft to set the load on the ground. He gives the release signal. At this time, the apex fitting
should fall free of the cargo hook. If it does not, the signalman has the aircraft hover, then he directs the
cargo-release team to move under the helicopter and manually release the load from the hook. The load
clears the hook. After the release, everyone moves out from under the aircraft. The signalman directs the
aircraft to depart and quickly moves out of its path. If the pilot cannot activate the cargo hook from within
the helicopter, and if cargo release personnel open it, then ground-crew members must use the following
emergency cargo release procedures: |
3-21.38 | 113 | External Loads
y If a donut ring or basket hitch is used, try to disassemble the apex/donut. Pass the pin/ADS
through the hook.
y If the cargo hook is attached to a clevis or apex fitting, unscrew the nut on the clevis or fitting
and remove the pin.
y If necessary, derig the load so the aircraft can set down.
HOOKUP PROCEDURES DURING WHITEOUTS OR BROWNOUTS
5-91. The hazards of these conditions (snow or dust) prevent the use of a signalman or a
hovering hookup.
y Rig the load with a 20-foot or a 40-foot extension (as required) using 20-foot ADS with two or
three loops and the appropriate number of type IV link assemblies. Place an apex fitting at the
end of the extension.
y Lay the extension to the left of the load. The aircraft approaches normally, then taxis to the
location of the apex fitting and stops. Once the aircraft lands, the hookup person moves to the
aircraft and attaches the apex fitting to the cargo hook. The aircraft suspends the load and
departs as directed by the GTA.
y When attaching the extension to skid-equipped helicopters, such as the UH-1H, take care that
the sling goes forward of but not through the skid. Then attach it to the cargo hook.
WARNING
Before the operation begins, coordinate the ground crew's
evacuation route to a rendezvous point. Proper coordination with
the liaison officer or helicopter crew prevents confusion.
Helicopter emergency procedures depend on terrain, wind
direction, and pilot choice. Good coordination also prevents the
helicopter and ground crews from moving in the same direction.
SLINGLOAD INSPECTION RECORD
5-92. To improve slingload safety, the Department of the Army implemented inspection procedures for
all Army equipment moved by the slingload method of air delivery. These procedures went into effect 1
October 1997. All Army loads require inspection by a qualified inspector before the arrival of the
supporting aircraft. The inspector completes the Slingload Inspection Record. (Figure 5-20, page 5-30,
shows an example completed DA Form 7382-R, Sling Load Inspection Record.) This form is used to
inspect all loads, to include nonstandard, or unique, loads. The commander with high risk approval
authority (usually the first colonel in the chain of command) is the approval authority for a nonstandard
load, and will be annotated in the remarks block of the DA Form 7382-R.
INSPECTOR QUALIFICATIONS
5-93. Inspectors must hold the grade of E-4 or more. They must also either be a pathfinder, a slingload
inspector course graduate, or air assault- qualified. |
3-21.38 | 114 | Chapter 5
DISTRIBUTION OF THE SLINGLOAD INSPECTION RECORD
5-94. Reproduce the slingload inspection record onto 8 1/2 by 11-inch paper, get it through official
distribution channels, or download it from the AEL. Complete the inspection record in triplicate. Copies of
the completed form are distributed as follows:
y Give a copy to the supporting aviation unit.
y Securely tape or tie a copy to the load.
y Give a copy to the supported unit.
Figure 5-20. Example completed DA Form 7382-R, Sling Load Inspection Record. |
3-21.38 | 115 | THIS CHAPTER IMPLEMENTS STANAG 3570.
Chapter 6
Drop Zones
The ground unit commander designates the drop zone, usually with the drop zone
support team leader's (DZSTL's) technical help. The drop zone is where drop aircraft
deliver personnel and equipment by parachute or free drop. The commander selects a
DZ location that best supports the tactical plan. In the case of tactical training, the
commander checks the USAF assault zone availability report (AZAR) to see if an
approved DZ already exists within the tactical area. If the AZAR does not include a
DZ in that area, the commander must assess the tactical situation before choosing a
DZ location.
SECTION I. SELECTION FACTORS
The commander uses the drop zone selection factors discussed in this section to analyze the suitability of a
drop zone.
AIRDROP AIRSPEEDS
6-1. The speed of the aircraft (airspeed) determines how long the aircraft will remain over the
drop zone. Table 6-1 shows airspeeds for rotary-wing aircraft in knots indicated airspeed (KIAS).
Table 6-2, page 6-2, shows the same thing, but for fixed-wing aircraft, by aircraft type and load.
Type of Aircraft Airspeeds
UH-1 Huey 50 to 70 knots (optimum 70 knots)
UH-60 Blackhawk 65 to 75 knots (optimum 70 knots)
CH-46 (USMC) 80 to 90 knots
MH-53 (USAF) 80 to 110 knots (optimum 90 knots)
CV-22 Osprey (USAF) 80 to 110 knots (optimum 90 knots)
CH-47 80 to 110 knots (optimum 90 knots)
CH-46/53 (USMC) 80 to 110 knots (optimum 90 knots)
CH-54 Skycrane 65 to 75 knots (optimum 70 knots)
CH/HH3 (USAF) 70 to 90 knots
MC-130 Combat Talon I and II 70 to 90 knots
C-130/141/17/5 130 to 135 knots (personnel/door bundles)
C-7A Caribou 90 to 120 knots
C-27A (Aeritalia G-222) 125 knots
C-46 Commando/C-47 Sky Train 104 to 125 knots
DC-3 (Contract Aircraft) 104 to 125 knots
CASA-212 90 to 110 knots
Table 6-1. Airspeeds for rotary-wing aircraft. |
3-21.38 | 116 | Chapter 6
Airspeeds
Type of Load C-130 C-141 or C-5 C-17
Personnel Static Line 130 130 to 135 130 to 135 (130 is ideal)
(130 is ideal)
Personnel HALO and HAHO 110 to 150 130 to 180 138 to 145
Container delivery system combination 130 to 140 150 140 to 150
and Equipment (See note)
Heavy equipment 140 150 150
Free fall (free drop) 140 150 140 to 150
High velocity CDS 130 to 140 150 140 to 150
(See note)
Wedge 130 to 140 150 140 to 150
(See note)
Ahkio sled 130 to 140 150 140 to 150
(See note)
Combat rubber raiding craft (CRRC) 130 to 140 150 140 to 150
(See note)
Door bundle 130 130 to 135 130 to 135 (130 is ideal)
(130 is ideal)
Simulated airborne training bundle Use same load as Use same load as for Not applicable
(SATB) (does not apply to C-17) for actual drop actual drop
High Speed, Low-Level, Aerial Delivery En route airspeed
System (HSLLADS)
Note: Use this type of load when gross weight exceeds 120,000 pounds. For combination drops, use the
higher airspeed KIAS. (A combination drop exists when the same or different type aircraft drop different
types of loads in the same pass over the DZ.)
Table 6-2. Airspeeds for fixed-wing aircraft.
DROP ALTITUDE
6-2. The DZSTL measures drop altitude in feet AGL (Table 6-3) from the highest point on the DZ (the
highest field elevation) to the aircraft. In combat (wartime) operations, airborne and airlift commanders
jointly determine drop altitudes. Table 6-4 shows drop altitudes, by load and aircraft type, in feet AGL.
A Distance from highest field 800 Feet AGL
elevation in DZ to desired altitude
of aircraft, in feet.
B Highest field elevation in feet above + 550 Feet field elevation
sea level, rounded up to next 50
(for example, round 505 up to 550).
C Drop altitude in feet indicated. 1,350 Feet indicated
Table 6-3. Example calculation of drop altitude in feet indicated. |
3-21.38 | 117 | Drop Zones
6-3. Table 6-4 shows airdrop altitudes for different types of training missions. (For more information
on drop altitudes, see AFI 11-231 and AFI 11-410.)
6-4. The aircraft altimeter displays altitude in feet indicated (feet above sea level), not in AGL (feet
above the highest point on the ground). Thus, the pilot might request the drop altitude in “feet indicated.”
You can calculate this simply by following this example:
y Obtain the drop altitude, that is, the distance in feet from the highest point on the drop zone
(field elevation) to the desired altitude of the aircraft. In this example, drop altitude equals 800
feet (A, Table 6-3).
y Obtain the highest field elevation in feet above sea level. Round this number up to the nearest
multiple of 50 (round 537 up to 550, for example) (B, Table 6-3). For purposes of obtaining the
drop altitude in feet indicated, use this number for field elevation.
y Sum the two numbers you obtained to yield drop altitude in feet indicated (C, Table 6-3).
Time of Day Rotary Wing Aerial Delivery
Type of Load (Light Conditions) Altitudes
Personnel Day or Night 1,500 Feet AGL
(includes limited visibility)
Bundles Day 300 Feet AGL
Night 500 Feet AGL
(includes limited visibility)
Note: If the rotary wing aircraft is flying 90 KIAS or faster, then it can drop personnel as low
as 1,250 feet AGL.
Type of Load Fixed Wing Aerial Delivery Altitudes
Planning 1,000 feet AGL
Combat operations (war) Determined jointly by airborne and airlift commanders
Tactical training 800 feet AGL
Basic airborne training 1,250 feet AGL
HALO (minimum opening) 2,500 feet AGL
Simulated airborne training 500 feet AGL
bundle-personnel (SATB-P)
Tactical training bundle (TTB) Use drop altitude of simulated load
Table 6-4. Airdrop altitudes for rotary- and fixed-wing aircraft.
TYPE OF LOAD
6-5. The type of load is considered when estimating the drop zone time requirement, or how many
bundles or personnel can be exited in a single pass over the drop zone. This is a consideration as a
commander may request a DZ capable of exiting a certain amount of jumpers in a single pass, or may need
to know how many jumpers can exit over a preselected DZ. For personnel, allow one second for each
jumper after the first. For example, ten jumpers minus the first jumper equals nine jumpers. Multiply nine
times one second. Allow nine seconds for all ten jumpers to get out the door. For equipment, allow three
seconds for each door bundle after the first. For example, five bundles minus the first bundle equals four
bundles. Multiply four times three seconds each. Allow twelve seconds to get the equipment out the door.
There is no set time to wait between exiting bundles and personnel. However, the jumpmaster team must
ensure all bundles have exited the aircraft, and that no unsafe conditions exist, before they start exiting
personnel IAW Chapter 10 of FM 3-21.220. Bundles and personnel must never exit at the same time. |
3-21.38 | 118 | Chapter 6
DANGER
Never allow personnel and bundles to exit the aircraft at the
same time.
6-6. For container deliver system (CDS) and heavy equipment, the time requirement is already
factored into the minimum computed air release point (CARP) DZ sizes found in AFI 13-217.
METHODS OF DELIVERY
6-7. The type of airdrop determines method of delivery. The three methods are low-velocity,
high-velocity, and free-drop trips. The method then normally determines the location of the control center.
Table 6-5 shows the minimum airdrop altitudes, by aircraft, load, and parachute type.
USAF Fixed-Wing Aircraft: Door Bundles
Type of Parachute Altitude for C-5, C-17, and C-141 Altitude for C-130
G-14 300 feet AGL 300 feet AGL
T-10 cargo 300 feet AGL 400 feet AGL
C-5, C-17, C-141: Container Delivery System
Type of Parachute Number Parachutes or Containers Airdrop Altitude
Planning drop altitude NA 600 feet AGL
G-12D Single canopy 1 to 6 containers 475 feet AGL
7 or more containers 575 feet AGL
2 or 3 parachutes 525 feet AGL
G-12E Single canopy 1 to 40 containers (130 425 feet AGL
KIAS)
Single canopy 1 to 40 containers (140 375 feet AGL
to 150 KIAS)
2 or 3 parachutes 550 feet AGL
G-14 1 or 2 containers 300 feet AGL
3 containers 400 feet AGL
12- to 22-foot NA 100 feet plus vertical distance for the
high-velocity ring-slot load being drop
parachute
26-foot high-velocity NA 100 feet plus vertical distance for the
ring-slot parachute load being drop
SATB-C NA See parachute type being simulated
Table 6-5. Minimum aerial delivery altitudes. |
3-21.38 | 119 | Drop Zones
C-130: Container Delivery System
Type of Parachute Number Parachutes or Containers Airdrop Altitude
Planning drop altitude Single canopy 1 to 6 containers 600 feet AGL
G-12D/E 7 or more containers 400 feet AGL
G-12D 2 or more parachutes 600 feet AGL
2 or more parachutes 600 feet AGL
G-12E 2 or more parachutes 550 feet AGL
CRRC (G-12D/E) NA 600 (boat only) otherwise use personnel
drop
G-14 1 or 2 containers 400 feet AGL
3 containers 500 feet AGL
12- to 22-foot high-velocity NA 100 feet plus vertical distance for the load
ring-slot parachute being drop
26-foot high-velocity NA 100 feet plus vertical distance for the load
ring-slot parachute being drop
SATB-C NA See parachute type being simulated
C-5, C-17, C-141, C-130: Heavy-Drop Equipment
Cluster Size (Number of Altitude for Altitude for
Type of Parachute Canopies or Bundles) C-5, C-17, and C-141 C-130
Planning drop altitude NA 1,100 feet AGL 1,100 feet AGL
G-12D NA 650 feet AGL 2 to 3 parachutes 650 feet
AGL
G-12E NA 550 feet AGL 2 to 3 parachutes 550 feet
AGL
G-11A 1 900 feet AGL 900 feet AGL
2 to 7 1,100 feet AGL 1,100 feet AGL
8 1,300 feet AGL 1,300 feet AGL
G-11B 1 700 feet AGL 700 feet AGL
2 to 4 750 feet AGL 750 feet AGL
5 to 7 1,100 feet AGL
8 1,300 feet AGL
G-11C/X 1 to 2 975 feet AGL 1,050 feet AGL
3 to 4 1,025 feet AGL 1,100 feet AGL
5 1,075 feet AGL 1,150 feet AGL
6 to 7 1,125 feet AGL 1,200 feet AGL
8 1,225 feet AGL 1,300 feet AGL
SATB-H NA See parachute type being See parachute type being
simulated simulated
NOTES: 1. Combination drops use the highest airdrop altitude. A combination drop exists when either of the
following occurs:
* When different aircraft drop different types of loads in same pass over DZ.
* When different type loads exit same aircraft in same pass over DZ.
2. Minimum airdrop altitude for heavy equipment using the 5,000-pound parachute release is 1,000 feet AGL or by
parachute type, whichever is higher.
Table 6-5. Minimum aerial delivery altitudes (continued). |
3-21.38 | 120 | Chapter 6
LOW-VELOCITY AIRDROP
6-8. Low-velocity airdrops are used for sensitive equipment and personnel. The parachute slows the
rate of the descent to prevent damage to equipment or injury to personnel.
HIGH-VELOCITY AIRDROP
6-9. High-velocity airdrops are used to deliver certain supply items. The load must be rigged in an
airdrop container with an energy dissipater attached to its underside and a ring-slot parachute attached to
the top. The chute stabilizes the load and reduces the rate of fall, ensuring an acceptable landing shock.
FREE DROP
6-10. Free drops are used for nonsensitive items only. This type of load has no parachute to stabilize or
slow its rate of descent. Loads may require special packaging to prevent damage from impact.
ADDED RISK
6-11. When determining the suitability of the DZ and considering the method of delivery around
populated or built-up areas or airfields, the pathfinder also considers the added risk of injury to personnel
or damage to buildings when using high-velocity or free-drop methods.
OBSTACLES
6-12. To ensure a safe airdrop, and to ensure Soldiers can recover and employ airdropped personnel and
equipment, the ground unit commander should assess the risks of obstacles on the DZ and adjacent areas.
OBSTACLES TO PERSONNEL
6-13. This includes anything, natural or manmade, that could harm a parachutist or prevent mission
accomplishment.
OBSTACLES TO EQUIPMENT
6-14. This includes anything, natural or manmade, that could damage or hinder the recovery of
equipment.
Trees
6-15. Trees 35 feet (which is the distance from the top of a personnel parachute to the harness) or higher
that would impede recovery of personnel or equipment present an obstacle.
Water
6-16. Water at least 4 feet deep and 40 feet wide, and within 1,000 meters of any edge of the surveyed
DZ is an obstacle.
Power Lines
6-17. Power lines carrying 50 or more volts can kill a jumper. |
3-21.38 | 121 | Drop Zones
DANGER
Set up the DZ away from power lines. A 50-volt shock can kill a
jumper. Even if it does not, it could cause him to fall, and that
could kill him.
6-18. Try to site the DZ at least 1,000 meters from a power line. If you cannot, and a power line is
located within 1,000 meters of any boundary of the DZ, then you must coordinate with the local power
company to shut off the power to that line NLT 15 minutes prior to TOT. If this is not possible, then the
flying mission commander, aircrew, and jumpmaster must assess the risk. They should consider at least the
following:
y Type of jump.
y Jumpers' experience.
y Aircrew's experience.
y Ceiling.
y Surface and altitude wind limits required to approve, suspend, or cancel.
6-19. To further minimize risks, they should consider how they might alter the mission profile to raise
or lower drop altitudes, change the DZ run-in or escape headings, or remove inexperienced jumpers from
the stick. Also, if they can, they should clearly mark power lines with lights, smoke, or VS-17 panels.
DANGER
Set up the DZ away from power lines. A 50-volt shock can kill
a jumper. Even if it does not, it could cause him to fall, and that
could kill him too.
Also, never try to climb power line poles to position or affix
markings to the poles or the lines themselves. |
3-21.38 | 122 | Chapter 6
6-20. Figure 6-1 shows an example safety zone for when power lines fall within 1,000 meters of the
drop zone.
Figure 6-1. Recommended safety zones for high-tension lines.
Other Obstacles
6-21. This includes anything else, such as barbed wire fences, swamps, rocks, ditches, steep inclines, or
gullies, that could injure parachutists, damage or prevent the recovery of equipment, or interfere with the
mission.
ACCESS
6-22. Ground unit commanders should avoid any DZ that has a major obstacle between it and the
objective area. Ground unit commanders should also make sure the area has adequate routes to conduct
troop movement and to recover equipment. |
3-21.38 | 123 | Drop Zones
SIZE
.
6-23. Ground unit commanders must use the following minimum peacetime drop zone sizes for fixed
wing aircraft, unless a waiver is issued. During wartime and contingency operations, the commander at the
appropriate level may waive the DZ size. AFI 13-217 provides information about waivers.
COMPUTED AIR RELEASE POINT
6-24. The USAF prescribes the sizes of computed air release point DZs during peacetime
drop operations.
Heavy Equipment
6-25. The minimum CARP DZ size (Table 6-6, top section) measures at least 600 yards (549 meters)
wide by 1,000 yards (915 meters) long for one platform. Add 28 meters (30 yards) to the length and width
for each 100 feet above 1,100 feet.
Personnel
6-26. Table 6-6, bottom section, shows the CARP DZ size for personnel. The CARP DZ size for one
jumper is at least 549 meters (600 yards) by 549 meters (600 yards). For each additional jumper, add
64 meters (75 yards) to the length of the DZ.
Heavy Equipment
Altitude Drop Zone Length
(Agl In Feet) Width One Platform Additional Platforms
To 1,100 600 Yards 1,000 Yards Add 400 yards (C-130) or 500 yards (C-17
or C-5) to trailing edge for each additional
platform.
Above 1,100 Add 30 yards to DZ width and length for each 100 feet above 1,000 feet (Add 15 yards to each
side of the DZ).
Personnel
Altitude Drop Zone Length
(Agliin Feet) Width One Platform Additional Platforms
To 1,000 600 Yards 600 Yards Add 75 yards to trailing edge for each
additional parachutist. When using
CAPES, add 100 yards each instead.
Above 1,000 Add 30 yards to DZ width and length for each 100 feet above 1,000 feet (Add 15 yards to each
side of the DZ).
NOTES:
1. For day visual formations, increase width by 100 yards (50 yards each side). For SKE formation, increase width
by 400 yards (200 yards each side). Official sunset to sunrise, increase width by 100 yards for single ship visual
drops (50 yards each side) or 200 yards for visual formations (100 yards each side).
2. Official sunset to sunrise, increase length by 100 yards for visual drops (50 yards each end).
3. For personnel formations, minimum DZ basic width using center PIs is 1,240 yards for 2-ship elements and
1,800 yards for 3-ship elements. When using offset PIs, minimum basic width is 1,100 yds for 2-ship elements
and 1,300 yds for 3-ship elements.
Table 6-6. Size criteria for tactical airlift drop zones, personnel, and heavy equipment. |
3-21.38 | 124 | Chapter 6
Container Delivery System
6-27. Table 6-7 shows the CARP DZ sizes for the container delivery system.
CDS (C-130)
Number of Containers
Altitude
(AGL in Feet) Width Single Double Length
To 600 feet AGL 400 yards 1 1 to 2 400 yards
2 3 to 4 450 yards
3 5 to 6 500 yards
4 7 to 8 550 yards
5 to 8 9 or more 700 yards
Above 600 feet Add 40 yards to DZ width and length for each 100 feet above 600 feet (Add 20 yards to each
side of the DZ).
CDS (C-17)
Number of Containers
Altitude
(AGL in Feet) Width Single Double Length
To 600 feet AGL 450 yards 1 1 to 2 590 yards
2 3 to 4 615 yards
3 5 to 6 665 yards
4 to 8 7 to 16 765 yards
9 to 14 17 to 28 915 yards
15 to 20 29 to 40 1,065 yards
Above 600 feet Add 40 yards to DZ width and length for each 100 feet above 600 feet. Add 20 yards to each
side of the DZ.
High Velocity (HV) CDS (Using 12-, 22-, or 26-Foot, Ring-Slot Parachutes)
Altitude
(AGL in Feet) Width Length
Less than or equal 580 yards or 660 yards or 604 meters
to 3,000 feet AGL 530 meters Add 50 yards or 46 meters to the trailing edge for each additional row
of containers
More than 3,000 Add 25 yards or 23 meters to each side and 100 yards or 91 meters to each end for every
feet AGL 1,000 foot increase in drop altitude.
High Altitude Airdrop Resupply System (HAARS) CDS
Altitude
(AGL in Feet) Width Number of Containers Length
Less than or equal 500 yards or 1 to 8 containers 1,200 yards or 1,098 meters
to 3,000 feet AGL 457 meters
9 or more containers 1,900 yards or 1,739 meters
More than 3,000 Add 25 yards or 23 meters to each side and 50 yards or 46 meters to each end for every 1,000
feet AGL foot increase in drop altitude.
High Speed Low Level Aerial Delivery System (HSLLADS)
Altitude
(AGL in Feet) Width Length
NA 300 yards or
600 yards or 549 meters
274 meters
Table 6-7. Size criteria for tactical airlift drop zones, Container Delivery System. |
3-21.38 | 125 | Drop Zones
Additional Size Requirements
6-28. For each additional platform on a C-130, add 366 meters (400 yards) to the length of the DZ. For
each additional platform on a C-17, C-5, or C-141, add 458 meters (500 yards). For multiple aircraft not
flying in trail formation, add 100 yards to the width of all CARP DZs. From official sunset to sunrise, add
100 yards to the length and width of all CARP DZs. For SKE formations, increase the width by 400 yards.
For SKE formation, you need not add the 100 yards when the aircraft are not flying in trail.
6-29. For C-17s flying in personnel formations, the minimum width for a basic DZ, using center PIs, is
1,240 yards for two ship elements, or 1,800 yards for three ship elements. When using offset PIs, the
minimum width is 1,100 yards for two ship elements, and 1,300 yards for three.
Note: Multiply yards by 0.9144 to convert them to meters; divide meters by the same number to
convert them to yards. |
3-21.38 | 126 | Chapter 6
ARMY VIRS AND GMRS DROP ZONES
6-30. For the verbally initiated release system (VIRS) and for the ground-marked release system
(GMRS), allow a minimum size of 300 yards by 300 yards (275 meters by 275 meters). To determine the
required size of Army VIRS DZs, use the D=RT formula (Figure 6-2). For personnel jumps, allow a
100-meter buffer zone at the leading and trail edges of the DZ. If local regulations permit, the local
commander can waive these buffer zones.
Figure 6-2. Example application of D=RT formula. |
3-21.38 | 127 | Drop Zones
PARACHUTISTS OR BUNDLES
6-31. To calculate the maximum number of either parachutists or bundles that a GMRS or VIRS DZ of
given length can accept in one pass, use the T=D/R formula (Figure 6-3). You must know the type of
aircraft and drop speed, and type of exit. The T=D/R formula may also be used to calculate the same
information for a CARP DZ. In this case, measurement is from the PI to the trail edge of the DZ, minus the
buffer zone (personnel only). Minimum length for CARP DZ is 3 seconds. In all cases, once the PI is
established, the DZ time must be recalculated from the PI to trail edge, minus the required buffer.
Figure 6-3. Example application of T=D/R formula. |
3-21.38 | 128 | Chapter 6
LOAD DRIFT UNDER PARACHUTE
6-32. To calculate the amount of drift experienced by a load under a parachute, use the D=KAV formula
(Figure 6-4). Always round up to the next whole number.
Figure 6-4. Example application of D=KAV formula.
WIND
6-33. Measuring wind on the drop zone entails measuring both surface wind and mean effective wind.
Use an authorized wind-measuring device to measure surface (ground) wind speed, especially for
personnel and heavy equipment operations.
6-34. Mean effective wind (MEW) refers to the average wind from ground level to drop altitude.
Measure the magnetic azimuth to the balloon and note the reciprocal heading. This gives you the MEW
direction to report. Use the pilot balloon (PIBAL) to measure MEW. PIBAL circumferences include—
y 10 grams for day—57 inches.
y 30 grams for day—75 inches.
y 10 grams for night—74 inches.
y 30 grams for night—94 inches. |
3-21.38 | 129 | Drop Zones
6-35. At night, attach a small, liquid-activated light or 6-inch chem-light to the balloon to aid in
observation. Table 6-8A (this page) and 6-8B (page 6-16) show the PIBAL charts for the 10- and 30-gram
helium balloons, respectively. |
3-21.38 | 130 | Chapter 6
10-GRAM HELIUM BALLOON
Inflate balloon to 57-inch circumference for day and 74-inch circumference for night.
DROP ALTITUDE IN FEET
500 750 1000 1250 1500 1750 2000 2500 3000 3500 4000 4500
ASCENSION
70 02 02 01 01 01 01 01 01 01 01 01 01 TABLE
60 03 02 02 02 02 02 02 02 02 02 02 02
ALT
55 03 03 03 03 03 03 03 03 03 03 03 03 TIME (FT)
50 04 04 03 03 03 03 03 03 03 03 03 03 0:10 80
45 05 04 04 04 04 04 04 04 04 04 04 04 0:20 170
40 06 05 05 05 05 05 05 04 04 04 04 04 0:30 250
35 07 06 06 06 06 05 05 05 05 05 05 05 0:40 330
30 08 07 07 07 07 07 07 07 06 06 06 06 0:50 400
25 10 09 09 09 08 08 08 08 08 08 08 08 1:02 500
24 11 10 09 09 09 09 08 08 08 08 08 08 1:10 540
23 11 10 10 09 09 09 09 08 08 08 08 08 1:20 610
22 12 11 10 10 10 10 09 09 09 09 09 09 1:30 670
21 12 11 11 10 10 10 10 10 10 10 10 10 1:43 750
20 13 12 11 11 11 11 11 10 10 10 10 10 1:50 790
19 14 13 12 12 11 11 11 11 11 11 11 11 2:25 1000
18 15 13 13 12 12 12 12 12 11 11 11 11 2:44 1100
17 16 14 13 13 13 13 12 12 12 12 12 12 3:05 1250
16 17 15 14 14 14 13 13 13 13 13 13 13 3:49 1500
15 18 16 15 15 14 14 14 14 14 14 14 14 4:30 1750
14 19 17 16 16 16 15 15 15 15 15 15 15 5:11 2000
13 21 19 18 17 17 17 17 15 15 15 15 15 6:34 2500
12 22 20 19 19 18 18 18 18 17 17 17 17 7:58 3000
11 24 22 21 21 20 20 20 19 19 19 19 19 9:22 3500
10 27 25 23 23 22 22 22 21 21 21 21 21 10:44 4000
09 30 27 26 26 25 24 24 24 23 23 23 23 12:08 4500
ELGNA
NOITAVELE
Table 6-8A. Conversion chart for 10-gram helium (pilot) balloons. |
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