Military

Helicopter landing zones contain one or more helicopter landing sites. A control center is established at each landing site and a release point (manned or unmanned) is normally selected for the LZ ( STANAG 3619).

The ground unit commander, in coordination with the supporting aviation unit, selects the location of helicopter LZs that support the ground tactical plan.

4-1. REQUIREMENTS

Minimum landing space requirements and minimum distance between helicopters on the ground depend upon a number of variables. These requirements are covered by aviation unit SOPs, or they are prearranged by the aviation unit commander in coordination with the pathfinder leader. The final decision concerning 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 commander considers the following factors.

a. Number of Helicopters. Animportant factor is the number of helicopters required to land at one time at one site to accomplish the mission. It maybe necessary to provide another landing site(s) nearby or to land helicopters in successive lifts at the same site.

b. Landing Formations. When they can, helicopters should land in the same formation in which they are flying. However, planned formations may require modification for helicopters to land in restrictive areas. If a modification in flight formation is required for landing, use the change requiring the least shift in the formation (Figure 4-1).

c. Surface Conditions, Surfaces must be firm enough to prevent helicopters from bogging down, creating excessive dust, or blowing snow. Rotor wash on dirt, sand, or snow-covered surfaces may obscure the ground and should be avoided, especially at night. Remove from landing points debris that could damage the rotor blades or turbine engine(s).

d. Ground Slope. The ground should be relatively level and the slope should not exceed 7 degrees if the helicopter is to land safely (Figure 4-2). However, observation and utility helicopters can terminate at a hover over ground slopes exceeding 7 degrees to load or to off-load personnel or supplies. Large utility and cargo helicopters can also land on terrain with a slope ranging from 0 degrees to 7 degrees. From a 7- to 15-degree slope, direct pilots to hover, as appropriate. Make landings upslope whenever possible and avoid landing downslope.

NOTE: To determine slope in percentage or degrees, all measurements may be expressed in feet or meters. If the elevation on the map sheet is expressed in meters, convert meters into feet by multiplying by three. If in feet, convert to meters by dividing by three.

e. Approach and Departure Directions. The direction of landing should be over the lowest obstacles and generally into the wind, especially at night. However, if there is only one satisfactory approach direction, or if it is desired to make maximum use of the available landing area, most helicopters can land with a crosswind of 6 to 9 knots or a tailwind of 0 to 5 knots. For wind stronger than 9 knots, the pilot lands into the wind. The same considerations apply to departures from landing sites.

f. Prevailing Wind. Consideration of approach and or departure routes is more important than that of prevailing wind unless a crosswind velocity exceeds 9 knots. The ability to land crosswind or downwind depends on the type of helicopter. Small helicopters can accept less crosswind or tailwind than larger, more powerful helicopters.

g. Density Altitude. The density altitude is determined by altitude, temperature, and humidity. For planning, as density altitude increases, the size of the LZ must also be increased because high, hot, and humid conditions decrease the lift capabilities of helicopters using that site.

h. Loads. Most helicopters cannot climb or descend vertically when fully loaded. Therefore, a large area and better approach/departure routes are required for fully loaded helicopters than for empty or lightly loaded ones.

i. Obstacles. Landing zones should be free of tall trees, power lines, and similar obstructions on the approach/departure ends of the landing site. Obstacles within the landing site, such as rocks, stumps, holes, and thick grass or brush (over 0.45 meter or 18 inches), must be removed. For planning, an obstacle ratio of 10 to 1 should be used; that is, a landing point requires 100 feet of horizontal clearance from a 10-foot tree if helicopters must approach or depart directly over the tree.

NOTE: The helicopter unit commander makes the final decision on minimum landing requirements based on the effects of air density, slope, and surface conditions. These requirements should be available in oral instructions during early mission planning.

4-2. ALTERNATE SITES

Enemy action, unfavorable terrain, or changes in the tactical or logistical situation may require alternate landing sites. These are selected primarily by the ground unit commander to support the tactical plan. On the recommendations of the aviation unit commander and the pathfinder on the site, the ground commander (or his representative) decides when alternate sites will be used. Instructions concerning their use must be given to pathfinders by the fastest means available. Pathfinder and aviation unit commanders do not have the authority to shift to an alternate LZ(s) unless such authority has been specifically delegated by the supported ground unit commander.

4-3. LANDING POINTS

These are areas/points (designated by the pathfinder leader) that can support the weight of a helicopter. As a guide, a helicopter requires a relatively level, cleared, circular area from 25 to 100 meters in diameter for landing. This depends on the type of helicopter. The area around the landing point must be cleared of all trees, brush, stumps, or other obstacles that could damage the helicopter. Generally, a helicopter requires more landing area during darkness than during daylight. Considerations such as helicopter type, nature of load, climate, and visibility affect what size landing point is used for a particular landing site.

a. The surface of the landing point center must be level and sufficiently firm to allow a fully loaded helicopter to land and, if necessary, to shut down, restart, and depart without sinking into the ground. The term "hard surface" indicates the proper condition.

b. The entire landing point must be cleared of any loose material that could be blown up by the rotors. The term is "cleared to ground level." It would not, for instance, be necessary to clear grass up to 0.3 meter (1 foot) high that might cover a level field unless a fire risk existed. A dusty surface can be stabilized with water, if available. Snow can be packed to reduce the amount of blowing snow and removed to reveal hazards.

c. If ground obstructions cannot be cleared, some helicopter operations can be performed without the helicopter landing. The same dimensions for clearing and ground markings are required, but the helicopter hovers above ground obstructions that prevent it from landing. However, every effort is made by ground troops to improve landing point surfaces to allow the aircraft to land.

d. Recommended minimum distances between landing points within a landing site are measured from center to center as follows:

Size 1 landing point . . . . .25 meters.

Size 2 landing point . . . . .35 meters.

Size 3 landing point . . . . .50 meters.

Size 4 landing point . . . . .80 meters.

Size 5 landing point . . . . .100 meters.

The pathfinder element is task-organized to establish and operate the installations required by the tactical plan of the supported unit(s). These facilities may be within a single LZ or widely separated through-out a large area of operations. The pathfinder leader is normally at the most important site. For the establishment and operation of one helicopter LZ, the pathfinder element is organized in two working parties--a control center and a landing site party (also called the marking party). A landing site party is required for each site in the landing zone. The control center party and the RP party provide the same function for LZs or DZs.

4-4. CONTROL CENTER

The purpose of the CC is to coordinate aircraft in and around an LZ or DZ and to promote a safe, orderly, and expeditious flow of air traffic. The pathfinder leader selects the exact location of the CC upon arrival in the area. The CC is positioned to facilitate visual control of aircraft in and around the LZ or DZ.

a. For helicopter landing zones, the most desirable CC location is along the aircraft flight route, but displaced from the landing site. This will reduce compromise of the actual landing site location by enemy electronic warfare assets, although the tactical situation might dictate that the pathfinder leader be on the site for control purposes. When an LZ has more than one landing site, or during reduced visibility, the CC may be located to perform as a manned release point, or final approach fix, to provide positive navigational assistance to arriving aircraft.

(1) The RP is an established traffic control checkpoint and the final navigational checkpoint for aircraft approaching the landing site or air delivery facilities within an LZ or DZ.


(2) The RP is also used by helicopter serials as a final coordination point for control of planned ground or aerial supporting fires in and around LZs during the air movement phase of an air assault operation. The RP is normally not manned unless extremely difficult navigational problems are anticipated by the air movement commander. The location is tentatively selected from map or air photograph studies as an easily identifiable point on the planned flight route to the landing site. If manned, the RP should be on terrain that allows maximum effective use of long-range electronic and visual navigation aids.

c. A control center is organized to meet mission requirements. It may consist of a single pathfinder operating the GTA radio for a limited period at a small site, or it may be staffed as follows:

(1) LZ or DZ commander. He supervises aircraft landings and departures, airdrops, and other pathfinder activities in the LZ or DZ He may also be the GTA radio operator.


(2) GTA radio operator. He operates the radio used to maintain communications with pilots and provides the necessary advisories for his airspace.


(3) Internal radio net recorder. He operates the radio used to communicate with other pathfinder elements (when such a net is applicable and required). He aids in the control of aircraft by observation and maintains a record of aircraft arrivals/departures and the type loads (if required).

The landing site party consists of a site team leader and additional pathfinders/attached personnel, as required. However, a single pathfinder may establish and operate a small landing site for limited periods.

a. The site team leader is responsible for the reconnaissance, establishment, and operation of the landing site. He supervises the site and, at any time, may supervise the GTA radio operator. Some of his responsibilities include:

(1) Organizes at an objective rally point.


(2) Reconnoiters to determine:


(a) Long axis.


(b) Usable area.


(c) Ground slope (compute).


(d) Land heading.


(3) Determines best landing formation.


(4) Designates slingload point(s).


(5) Emplaces and briefs GTA radio operator.


(6) Clears touchdown and slingload points.


(7) Organizes personnel and loads for air movement.


(8) Clears or marks obstacles.


(9) Prepares for night/day missions.


(10) Continues to improve site.

c. Other personnel from supported units may be attached to the landing site party to provide security, assist pathfinders in establishing and operating the landing site, reconnoiter and mark assembly areas, and operate assembly aids. Attached personnel must be briefed and rehearsed. If they are given a reconnaissance assignment, it should not include actual landing areas; these areas are reconnoitered by pathfinders.

Once a site has been selected and communications established, the operation of the site begins. Additional markings and improvements are continually made until the site is ready to support the ground tactical plan.

4-6. COMMUNICATIONS

Communications are established in the GTA net and the pathfinder internal net (if used) immediately upon arrival at the landing site. These radio nets are monitored at all times (unless otherwise directed) until operations at the site are completed.

a. Each helicopter landing site should be within ground communication range of the other sites and RPs (if manned). However, the tactical situation may preclude this requirement. The range of available radios dictates the ability of facilities within the LZ to communicate with each other.

b. The utility cargo helicopter landing site commander rapidly 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 and determines if the terrain or situation dictates any change to the planned landing formation. The site commander must also ensure that landing instructions are compiled for transmittal to inbound helicopters, and that obstacles in or around the site are removed or marked.

4-7. FLIGHT FORMATIONS

Helicopters should land simultaneously in a planned flight formation. If it becomes necessary to land in a formation different from that in which they are flying, the landing site commander ensures that this information is given to the flight leader as part of the landing instructions. The exact layout of the landing site depends upon helicopters not flying directly over other aircraft on the ground, available landing space, number and type of obstacles, unit SOPs, and prearranged flight formations.

4-8. LANDING ZONE AND OBSTACLE MARKING

Normally, no LZ marking is used for day operations except smoke or some other minimum identification means. For night operations, lanterns or field expedients are used to indicate the direction of landing and to mark individual landing points (Figures 4-4 through 4-9). However, obstacles should be marked for daylight and night air assault operations.

a. At night, lights of different colors may be used to designate different helicopter sites or to separate flights within a larger formation. Alighted T or inverted Y indicates the landing point of the lead helicopter of each flight and the direction of approach (Figure 4-10). Additional lights are provided for touchdown points of other helicopters in the flight. Helicopters should land with the right landing gear or skid just to the left of the light. (Red lights are avoided because they mark obstacles.)

b. When helicopters are inbound, all lights should be hooded or turned upside down for security until the last practical moment. Lights should be beamed in the direction from which the helicopters approach. A signalman should be used to direct the landing of the lead helicopter.

4-9. AIR ASSAULTS

During daylight air assault operations, obstacles that may be difficult to detect and impossible to remove (such as wires, holes, stumps, and rocks) are marked with colored panels or any other easily identifiable means (colored red). During night air assault operations, red lights are used to mark all obstacles within a landing site that cannot be easily eliminated.

a. In most combat situations, the need for security prohibits the use of red lights to mark the tops of trees on the departure end of a landing zone. In training, however, or in a rear area landing site, red lights should be used whenever possible. If obstacles or hazards cannot be marked, aviators should be fully advised of existing conditions by GTA radio. In any case, the pathfinder landing site leader ensures that the most dangerous obstacles are marked first and, if possible, eliminated.

b. Pathfinders may mark initial assembly points for troops, equipment, and supplies if required by the supported unit. These points are located to facilitate assembly and clearing of the helicopter site quickly and efficiently. If unit assembly areas are to be used, they arc selected by the ground unit commander. If necessary, supported ground unit personnel accompany the pathfinders to reconnoiter and mark the unit assembly areas, establish assembly aids, act as guides, and assist in landing and unloading operations. Such help for pathfinders ensures the rapid clearing of troops, supplies, and equipment from the landing points.

c. Pathfinders have a limited capability to secure a landing site. If they precede the initial assault elements into a landing site, personnel from the supported ground unit may accompany them for security.

4-10. INTERCEPT HEADING

The heading from the RP (or CCP if no RP is used) to the landing site coincides as closely as possible with the landing direction to preclude sharp turns by helicopter formations. The larger the formation, the more important this becomes. If a straight-in landing approach is not possible, then an intercept heading should be established (Figure 4-11). The intercept point should be far enough from touchdown that it allows helicopters in formation a final approach of at least 1 to 2 miles. Visual steering commands, time and distance, terrain features, and electronic or visual navigation aids may be required by flight leaders to determine the intercept point and the landing direction at the landing site.

Helicopters approach the LZ along a designated flight route. They are normally organized into serials containing four or five helicopters but may be platoon-size lifts. One serial may contain a flight for each helicopter site. However, flights of medium or heavy transport helicopter (CH-47 and CH-54), carrying artillery or other bulk cargo, can often be expected to arrive at LZs in increments of one or two helicopter (Figure 4-12). Subsequent flights follow at minimum time intervals, which depend on the number of helicopters per flight, the configuration and conditions of the landing site, and the nature of the cargo to be loaded or unloaded. The aviation unit commander determines the time between successive flights during planning. Once an operation is in progress, pathfinders at the site may recommmend changes to ensure helicopter safety or to expedite operations. (Night operations may increase the time and distance between formations.)

4-11. COMMUNICATIONS CHECKPOINT

As each helicopter serial reaches the CCP on the flight route, the flight leader contacts the appropriate helicopter landing site control center. The CC then gives the flight leader the heading from the CCP to the landing site, the landing direction, and the following other pertinent information:

• The enemy situation.
  

• Friendly Field elevation.
  

• Landing formation.
  

• Terrain conditions.
  

• Traffic situation.
  

• Obstacles.
  

• Availability of smoke or light gun.
  

• Visual approach path indicator setting.
  

• The next reporting point.
  

NOTE: Pathfinders are prepared at all times to provide ATC and navigation assistance to all aircraft in and around the landing site in the event those aircraft do not follow a specified flight plan.

b. The helicopter formation continues along the flight route to the RP. Pilots are assisted by the electronic and visual navigation aids at the RP (if manned). All helicopters pass over or near the RP, and each flight RP (if manned). All helicopters pass over or near the RP, and each flight serial leader reports passage of the RP to his respective landing site CC and then flies directly to his assigned landing site. The individual landing site CC assists any flight that cannot locate its site, using visual signals, steering commands, or electronic homing techniques.

(1) Day operation signals. For daylight operations, a specified smoke color may be assigned to identify different landing sites. Since the number of smoke colors is limited, the same color may have to be used by more than one helicopter site. Sites that use the same color should be farther apart. Smoke is employed sparingly because it marks a location not only for friendly forces, but for enemy observers as well. Generally, smoke is used only in response to a pilot's request for help in identifying or locating his helicopter site.


(2) Night operation signals. For night operations, pyrotechnics or other visual signals are used in lieu of smoke. As in daylight, red signals mean do not land, or they indicate other emergency conditions. Emergency codes must be planned and understood by all concerned. Each flight lands at its assigned site in the manner indicated by CC messages and the visual aids displayed. Pathfinders may use arm-and-hand signals to assist in controlling the landing, hovering, and parking of helicopters.

As required, pathfinders maybe tasked to manage ACPs to assist aircraft en route to the LZ.

a. The ACP party consists of two or three pathfinders, or at least one pathfinder with assistants. They position and operate the electronic and or visual navigation aids. They also operate radios in the pathfinder internal net (if used) and the GTA net. Monitoring the GTA net permits ACP personnel to respond immediately to requests from pilots for assistance in locating an ACP.

b. The pathfinder in charge of the ACP (assisted by available personnel as needed) installs navigation aids immediately upon arrival at the site (or according to plan). Whenever possible, aids should be established concurrently. If a priority for installing these aids is required due to limited personnel or other factors, then the following priority is used.

(1) GTA radio This is placed into operation first. The electronic homing beacon is then installed, if requested by the aviation unit commander, since it affords long-range guidance. If used, the beacon must be far enough away to prevent excessive interference with the radios and to reduce the possibility of enemy fire destroying the radios and the beacon simultaneously.


(2) Visual navigation aids. These navigation aids vary in number and type depending upon aviation unit SOPs and requirements, and the need for security. Grass or brush masking these aids is removed, but a method of concealing the markings is necessary if enemy aircraft is sighted.


(3) Pathfinder internal net recorder He establishes communication with the landing zone CCs as quickly as possible to report the state of ACP readiness and to provide information on the enemy situation near his location (if appropriate). He constantly monitors the radio unless directed to operate a beacon on a definite time schedule.


(4) Security personnel. The ACP party may include attached personnel from supported units who are used to provide security. They move to assigned locations and take up security positions or assist in establishing and operating navigation aids and communications equipment.

Daytime visual references (checkpoints for positive identification) are difficult to see at night. Visual aids for night navigation emit illumination. Too few visual references may cause pilots to concentrate on a single light or a group of lights in a concentrated area. This may induce visual illusions and can cause vertigo. To eliminate this unsafe phenomenon, avoid marking LZs with a single light. Landing areas should always be lighted with two or more lights that are widely separated.

4-13. TACTICAL LANDING LIGHTS

The tactical landing light system provides visual cues for landing in a tactical landing site. The inverted Y is the recommended system when the approach is made from terrain flight altitudes. Approaches to a tactical landing site are normally made without the aid of the search landing light. The lighting for a tactical landing zone may consist of hand-held flashlights or "beanbag" lights arranged on the ground. Regardless of the type lighting device used, a minimum of two lights will be used to identify the touchdown point.

a. At night, lights of different colors maybe used to designate different helicopter sites or to separate flights within a larger formation. A lighted (inverted) Y indicates the landing point of the lead helicopter in the flight (Figure 4-13). At additional touchdown points, helicopter should land with the right landing gear or skid just to the left of the light. All lights should be hooded or turned upside down for security until the last practical moment when helicopters are inbound. Lights should be beamed in the direction from which the helicopters approach. A signalman should be used at a slingload point.

b. During darkness, approaches are slightly steeper and slower than a daylight approach.

c. One example of emergency night lighting is to use vehicle headlights. Place two vehicles about 35 meters apart and 35 meters downwind of the landing point with their headlight beams intersecting at the center of the landing point (Figure 4-14). The helicopter approaches into the wind, passes between the vehicles and lands in the lighted area. This method is not suitable for large helicopters.

4-14. EXTERNAL LOADS

External load employment can be difficult during darkness; however, several methods are available to the pathfinder. In the absence of sufficient signalmen, reference lights (three lights spaced triangularly 5 meters apart) are positioned 25 meters in front of the load as a marker. This lighting configuration aids the flight-crew during hookup, lift-off, and landing. Upon lift-off, the aircraft climbs vertically until the load clears the ground. As the helicopter begins forward movement, sufficient power is applied to maintain a climb that allows the slingload to clear obstacles along the lift-off path. The shorter the sling, the less altitude required to clear obstacles. Sling length should be added to obstacle height for computation of the distance required for departure clearance.

4-15. MULTI-HELICOPTER OPERATIONS

Due to reduced vision at night, formation flying cannot be safely conducted in a complete blackout mode at terrain flight altitudes unless the unit is equipped with night vision goggles.

4-16. NIGHT VISION GOGGLES

To operate at terrain flight altitudes during low- or mid-light levels, use night vision goggles. Because the lights in the tactical lighting set are too bright for these goggles, place a filter over the clear lens cover. If a filter is not available, paint the lens cover or cover it with plastic tape to reduce light intensity.

The pathfinder unit can anticipate supporting the aviation commander and ground unit commander in a variety of climates and terrains. The requirements for establishing a landing site or zone are similar. However, some land areas require extra precautions and care in the selection and preparation of an LZ to safely and expeditiously receive aircraft.

4-17. PILOT INPUT

It is important to remember that the pilot (based on his experience and responsibilities to aircraft and crew) determines whether or not a proposed landing site is safe.

a. Climatic and terrain environments include cold weather, 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 90-6.)

b. Each area requires special procedures on the part of the pilot. The pathfinder who is knowledgeable regarding these procedures can better advise and assist aviators and the supported ground unit.

4-18. COLD WEATHER OPERATIONS

Cold weather flying conditions may be encountered in many parts of the world. Extreme cold and blowing snow pose special problems in ground operations and flight conditions. The problems presented by ice, snow, or rain are incorporated into pathfinder mission planning. The pathfinder's knowledge of flight procedures enables him to advise the pilot on the existing surface conditions.

a. Communications. Radio communications are generally good, but may be disrupted by electrical disturbances (the aurora borealis). Some frequencies may be blocked while other frequencies will not always permit operators to transmit clearly. Communications are often limited or restricted by mountainous terrain. Relay stations may have to be established. Conditions of "radio skip" are prevalent in cold weather areas, and it is common to experience long-distance radio traffic on tactical frequency modulated networks.

b. Navigation. In snow-covered areas with flat terrain, pilots may require RPs to be reamed and marked. When flight is over loose snow, the movement of the air picks the snow up and circulates it, forming a snow cloud. If this condition exists, a phenomenon referred to as "whiteout" may occur. Visibility is reduced to zero as the aircraft descends or climbs through a snow cloud. The occurrence of whiteout conditions places additional requirements on the landing site party (Figure 4-15).

c. Surface Conditions. The surface must be evaluated to determine if aircraft can land without sinking too deep into the snow. Testing the snow surface hardness can be done with a tactical vehicle. The landing site party should also try to determine the degree of ground slope and whether or not there are any obstacles beneath the snow cover at each landing point.

(1) The distance between aircraft is increased along with the size of the landing point: 100-meter-diameter landing point with 100 meters between aircraft.


(2) Marking the landing points presents other problems. Pilots lose depth perception in snow-covered areas. A signalman on the ground provides a good reference for estimating height. Touchdown points in daytime are marked so the pilot has references to clear and safe landing areas.


(3) The GTA radio operator, if the tactical situation permits, advises the pilot of the surface conditions so he may anticipate how to make an approach. The echelon left or right landing formation is preferred to reduce the chances of snow clouds or whiteouts for the other aircraft. The pathfinder should also plan to stagger aircraft arrivals to the landing site to allow for the settling of snow clouds from preceding aircraft.


(4) Depending on the mission requirements, climatic conditions, and the time the landing site is used, the pathfinder leader considers the use of multiple landing sites instead of only one site.


(5) Aircraft making night approaches to snow sites require a reference point on-the ground (tactical landing lights or runway lights). These lights provide the pilot with a reference for judging angle of descent and rate of closure. The pilot plans his approach to land short of the touchdown point to ensure that he will not overshoot the point and have to decelerate rapidly in a snow cloud. Approaching short allows the pilot to maintain airspeed after the level-off, thus keeping the aircraft in front of the snow cloud until touchdown.


(6) The pathfinder, if coordinated with the flight commander, may adjust his inverted Y forward 10 meters in front of his designated number 1 touchdown point. This allows the landing site party to employ all usable areas on the site.


(7) If personnel are available, they may be positioned to act as signalmen for aircraft approaching additional touchdown points. Caution is exercised to ensure that signalmen are in safe areas as aircraft approach and land. Additional signalmen should also control the loading of personnel on the aircraft (as instructed by the crew chief or the crew) when the aircraft is ready to be loaded.

e. Slingload Operations. Hookup and lift-off with a slingload over snow can be unsafe unless the pilot anticipates being engulfed by a snow cloud. (The CH-47 requires a sling length of at least 60 feet. The sling length for other aircraft is shorter.) The usual technique of hovering the helicopter over the load and attaching the sling to the hook mayor may not be used over snow-covered terrain.

(1) An alternate procedure for hooking up a slingload is for the pilot to land the helicopter to the left of the load but close enough so that the sling can be attached to it.


(2) When ready for lift-off, the pilot initiates a slow, vertical ascent with enough lateral movement to position the aircraft over the load. He continues a vertical ascent until the load is off the ground and a hover-power check is completed. When the load is clear, the pilot begins acceleration while continuing to climb.

f. Static Electricity. During cold weather, static electricity creates serious problems. It can be generated by the movement of an aircraft through the air, by brushing snow and ice from the aircraft, or by dragging steel cables over the snow. During external load operations, aviators should key the FM radio immediately before load pickup to discharge the aircraft's static electrical charge. However, the charge rapidly builds up again. Therefore, hookup personnel should use a grounding device to avoid electrical shock (Chapter 6, static probe).

g. Safety Considerations. The accumulation of ice on aircraft structural and moving parts may be dangerous to nearby ground personnel. The aircraft may 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 may shed while the helicopter is losing altitude during the landing approach and during touchdown, and pieces of ice shed by the main rotor may travel up to 300 feet. Ground personnel should stay a safe distance away from helicopters during landingdhutdown(after flight in icing conditions), and passengers should not get out until the rotor blades have stopped.

4-19. JUNGLE TERRAIN

Jungle areas impede military operations and tend to obstruct military lines of communication. Jungle areas maybe characterized by heat, humidity, rainy seasons, and other weather conditions that affect the performances of aircraft. Thick vegetation, irregular terrain, and adverse atmospheric conditions screen radio transmissions. Radio relays may have to be used. The CCP may have to be manned and marked, and GTA communications provided to advise and direct the pilot to the landing site if communications are limited in range.

a. Landing sites in the jungle are generally small and may accommodate only a few aircraft. The ACL will be drastically reduced. The surface conditions of the landing site should be evaluated to ensure that the aircraft will not sink or bog down in the soil. The site is surveyed for vines, trees, and other obstructions in the approach path and near the touchdown point.

b. On the approach, the pilot avoids a high rate of descent. The aircraft angle of descent should be steep enough to permit clearance of any obstacles. Normally, a 10-to-l obstacle ratio is used, but the ratio can be reduced to no less than 5 to 1. The pathfinder leader considers obstacle height on approach and departure ends. Due to density altitude problems in tropical areas, the aircraft may not be able to develop enough lift to clear tall obstacles. When the size of the site and terrain conditions permit, the pilot may consider running lift-offs and landings. However, a running-type lift-off may not be possible in the jungle due to the size of the site, soft terrain, and obstacles.

c. Depending on the tactical situation, the use of lights in night jungle LZ operations maybe restricted.

d. Site security is critical to the success of the ground unit commander's mission. Due to the cover and concealment provided by jungle terrain, landing site security is difficult to accomplish. The pathfinder team leader coordinates with the flight commander to set a specific time period to light the site.

e. It is important that the site is oriented to the direction of the wind and that departure obstacle ratios are as low as possible due to climatic conditions, jungle vegetation, and reduced lift capability of the helicopter. The pilot will hover as low as possible and no longer than necessary due to the aircraft's decreased lift efficiency caused by ground effects.

4-20. DESERT TERRAIN

The typical desert is a dry, barren region, generally treeless and sandy. A region of environmental extremes, it has violent and unpredictable changes in weather and contains terrain that does not conform to any particular model. While frequent clear days offer unequaled visibility and flight conditions, a sandstorm can quickly halt all operations. Therefore, successful desert operations require special training, acclimatization, and a lot of self-discipline.

a. Communications. In desert operations, the radio is usually the prime means of communication. Radio range normally is good due to the low, rolling terrain. However, because of the increased distance involved with military operations in the desert, FM radio communications maybe inadequate, especially when using the higher FM frequencies. High-frequency radio equipment is essential. Factors attributed to communication problems include poor electrical ground, and sand and dust entering equipment. Because of increased distances between land force units engaged in desert operations, helicopters maybe used to provide air or ground relay, or to help deploy ground radio rebroadcast facilities.

b. Navigation Assistance. Many of the conditions experienced in cold weather operations are similar to desert operations. Distances and altitudes are also difficult to judge in the desert. The lack of definable terrain features makes navigation difficult, especially at night and over long distances. The sameness of the terrain makes it easier for a pilot to become less attentive to his surroundings, and it may be necessary to mark and man release points.

c. Landing Sites. The climatic conditions in the desert will have a profound impact on establishing and operating landing sites. The three most important factors to consider are density altitude, wind, and sand (dust). Sand on a landing site could produce brownout conditions similar to those found in snow areas, and the same precautions are applicable. Therefore rocky areas are preferable to sandy areas, hollows, depressions, and sandy valleys.

d. Wind. Desert wind generally dies down about sundown for an hour or two, and there is also a calm before sunrise. At times the wind can achieve hurricane force. In all deserts, rapid temperature changes invariably follow a strong wind that often raises dense clouds of dust and sand. Consideration should be given to the time of day when the landing site will be operational.

(1) The extreme heat often experienced in the desert also affects the aircraft's ACL. When in support of a ground unit, the pathfinder leader coordinates with the aviation element to determine the ACL per type of aircraft. The distance between aircraft and landing point size are increased in desert operations (100 meters between aircraft, 100-meter-diameter landing points). In daylight hours, the touchdown points are marked (sandbags painted a bright color or other expedient method). The use of signalmen, if available, is encouraged.


(2) When establishing a landing site, the pathfinder leader considers taxi procedures. When it is necessary to taxi, the pilot gets the aircraft into a vertical position as quickly as possible to minimize sand (dust) intake by the engines and to avoid a brownout. He should avoid taxiing over the same area repeatedly.

f. Landings. Running-type landings should be used when possible to minimize sand intake. If a running landing can be made, the touchdown roll is kept to a minimum to prevent overloading the landing gear. If the terrain does not permit a running landing, the pilot makes a landing using an approach angle that is greater than the angle used for normal approaches. A landing should not be made from a hover.

g. Safety Considerations. Ground crew personnel should wear clothing that affords adequate protection from the blowing sand created by rotor wash. Special care should be taken to keep sand out of the eyes, ears, nose, and mouth. The use of goggles, ear plugs, and cloth masks provide adequate protection for facial areas. Other ground crew procedures are similar to cold weather operations.

4-21. MOUNTAINS

Mountains are characterized by rugged, divided terrain with steep slopes and few natural or man-made lines of communication. Weather in the mountains is seasonal and fluctuates from extreme cold with ice and snow to extreme heat. Although these weather extremes are important planning considerations, the variability of weather over short periods of time also influences operations.

a. Communications. Communications are often limited or restricted by mountain terrain. To maintain them within the area of operations, aircraft may have to restrict operations to the vicinity of the unit or be assisted by additional aircraft employed as radio relay stations. Pathfinder units may have to establish radio relays at the RP and or CCP.

(1) Mountain operations are the most demanding on aviation and require the pilot to use large-scale terrain maps for precise flying.


(2) Since GTA communication is degraded by intervening terrain, navigation assistance and control over extended ranges may be difficult.

c. Density Altitude. In the mountains, density altitude can vary significantly between pickup points and landing zones and also at different times during a 24-hour period. For example, density altitude will normally peak in the late afternoon and reach its low point at dawn.

d. Mobility. The helicopter is the principal vehicle for rapidly moving forces in the mountains. During the offense, air assault operations may be conducted to infiltrate forces into the enemy's rear area and to bypass or envelop his defenses. In the defense, reinforcements and reserves can be moved rapidly by helicopter.

e. Landing Sites. Airfields for fixed-wing aircraft and multiple helicopter LZs in mountainous regions are limited. When only single aircraft LZs are available, in-flight spacing between helicopters is increased; this places an additional load on each crew. When conducting multiship operations into a small LZ, the pathfinder controller should allow sufficient time between lift-off and landing for the turbulent air generated by the aircraft during departure to stabilize. The pilot will experience a loss of lift and turbulent conditions if spacing between lift-offs and landings is inadequate.

(1) Mountain LZs are generally sloped, rough, and small. Because of this, pilots must use extreme care during touchdown. Depending on the angle of slope and available torque, a normal slope landing maybe made. Due to the size of cargo helicopters, some difficulty may be experienced in positioning the entire fuselage in the available area. The pilot loses visual reference to the ground when the cockpit extends over the landing area. Direction must be given by the crew chief and the signalman regarding the direction in which the helicopter should be maneuvered. LZs should be established on the windward side since the wind is more stable. However, location of the enemy is more important than placing the LZs on a leeward or windward side.


(2) During a mountain approach with uneven terrain surrounding the LZ, the pilot receives a poor visual clue as to the actual aircraft altitude and rate of closure. Where the terrain slopes up to the LZ, a visual illusion occurs, giving the pilot an impression that the aircraft is too high and the rate of closure is too slow. If the terrain slopes down to the LZ, the feeling is that the aircraft is too low and that the rate of closure is too fast. The employment of a signalman on the ground will provide a visual reference for pilot control adjustments. It maybe necessary to provide more than one signalman.

(1) Determine the size, slope, amount of surface debris, and the area covered by shadows and obstacles in and around the site.


(2) Determine the approximate direction, speed, and characteristics of the wind.


(3) Assess the inbound route if necessary. The aircraft may terminate at a hover to off-load troops and supplies if the slope is too great to permit a landing.


(4) Assess the departure route. Lift-off routes should be into the wind and over the lowest obstacles.

It is desirable to land the aircraft into the wind; however, the terrain and its effect on the wind may require that the pilot execute a crosswind landing. When making a crosswind landing, the approach path should be planned so that the wind is from the left side of the aircraft for single-rotor helicopters. This condition assists the pilot in overcoming the effects of torque, reduces power requirements, and aids in heading control. Other considerations include vertical air currents, escape routes, terrain contour and obstacles, and the position of the sun.

4-22. VERTICAL AIR CURRENTS

It is desirable to have updrafts on the approach path. The severity of the vertical currents encountered (updrafts or downdrafts) may be more critical than landing into the wind and may require a downwind approach.

4-23. ESCAPE ROUTES

There should be one or more escape routes along the approach path that can be used if a go-around is required.

4-24. TERRAIN CONTOUR AND OBSTACLES

The terrain and obstacles along the approach path should be low enough to permit the pilot to conduct a shallow approach angle into the landing site. When possible, select a landing point on or near the highest terrain feature.

4-25. POSITION OF THE SUN

Although the wind direction and nature of the terrain are the primary factors in selecting an approach path, consideration should be given to the location of the sun relative to the approach path and the presence of shadows on the landing site. If the landing point is in a shadow, the approach path should also be in a shadow. This would eliminate problems encountered by the pilot when adjusting from one light condition to another. An approach directly into the sun must be avoided when the sun is low on the horizon.