Military

a. Number of Helicopters. To land a large number of helicopters at the same time, the commander might have to provide another landing site(s) nearby. Or, he can land the helicopters at the same site, but in successive lifts.

b. Landing Formations. 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 4-1). However, in order to land in a restrictive area, they might have to modify their formation somewhat.

c. Surface Conditions. Pathfinders choose landing sites that have firm surfaces. This prevents helicopters from bogging down, creating excessive dust, or blowing snow. Rotor wash stirs up any loose dirt, sand, or snow. This can obscure the ground, especially at night. Pathfinders remove these and any other debris from landing points, since airborne debris could damage the rotor blades or turbine engine(s).

d. Ground Slope. Pathfinders choose landing sites with relatively level ground. For the helicopter to land safely, the slope should not exceed 7 degrees (Figure 4-2). Whenever possible, pilots should land upslope rather than downslope. All helicopters can land where ground slope measures 7 degrees or less.

e. Approach and Departure Directions. To land or to take off, especially at night, the helicopter pilot generally chooses the approach or departure path with the lowest obstacles. Ideally, this allows him to fly into the 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.

f. Prevailing Wind. 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.

g. Density Altitude. Altitude, temperature, and humidity determine the density altitude. Planners should try to remember that as the density altitude increases, the size of the LZ also increases. High, hot, humid conditions decrease lift capabilities.

h. Loads. 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.

i. Obstacles. Landing zones should have no tall trees, power lines, or similar obstructions on the approach and departure ends of the landing site. Pathfinders must remove any obstacles within the landing site. This includes any rocks, stumps, and holes; and thick grass or brush over 0.45 meter (18 inches). Planners figure on an obstacle ratio of 10 to 1 (ten to one). 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.

a. Choose a Hard Surface. Pathfinders choose a landing point with a "hard surface." That is, the surface of the landing point must allow a fully loaded helicopter to land, restart, and leave again, all without sinking into the ground.

b. Clear to Ground Level. 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, then pack it down firm, which will also reduce the amount blowing around.

c. Clear Around Obstacles. Ground troops must do everything they can to improve landing point surfaces so aircraft can land. However, even if pathfinders cannot clear ground obstructions, they can perform some helicopter operations without the helicopter landing. However, they must still clear and mark the area just as they would if the helicopter were going to land. Helicopters hover above the ground obstructions that prevent them from landing.

d. Measure the Shortest Distances Between Landing Points. 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 from center to center of the landing points (Figure 4-3). At the least, these distances must measure—

a. 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.

b. 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 ATC 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.

c. 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:

a. Site Team Leader. The site team leader reconnoiters, establishes, and operates the landing site. He supervises it and, at any time, may supervise the GTA radio operator. Some of his responsibilities include—

b. Extra Pathfinders. 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. Three factors dictate the number of extra pathfinders employed:

• The size of the landing site.

• The expected density of air traffic.

• The number and type of visual and electronic aids used.

• The tactical situation.

c. Commander. 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—

• Reconnoiter other areas.

• Provide security.

• Help pathfinders set up and operate the landing site.

• Reconnoiter and mark assembly areas.

• Operate assembly aids.

a. 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.

b. 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.

a. 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 4-11). 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 light.

b. For security, pathfinders and the ground unit cover or turn all lights upside down until the last practical moment before a helicopter arrives. Then, they beam the lights in the direction from which the lead helicopter is approaching, and a signalman directs its landing.

a. 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.

b. 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 operations. Having this help ensures that the pathfinders can rapidly clear 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, soldiers from the supported ground unit could go with them for security.

a. 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:

• Enemy situation.

• Friendly fires.

• Field elevation.

• Landing formation.

• Terrain conditions.

• Traffic situation.

• Obstacles.

• Availability of smoke or light gun.

• Next reporting point.

b. Before reaching the CCP, IAW instructions from the flight leader, all helicopters in a flight switch to the pathfinder control frequency.

c. 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.

a. The ACP party consists of two or three pathfinders, or at least one pathfinder and assistants. The party positions and operates electronic or visual navigation aids, or both. The party also operate 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.

b. 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:

a. 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.

b. 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 may also use different colors to separate flights within a larger formation. A lighted (inverted) "Y" indicates the landing point of the lead helicopter (Figure 4-14).

c. At other touchdown points, helicopters land with the right landing gear or skid just to the left of the light (Figure 4-15). Until the last practical moment, pathfinders hood or turn upside down all lights for security. They also place a signalman at a sling-load point. Then, they beam the lights in the direction from which the helicopters approach.

d. During darkness, helicopters approach slightly steeper and slower than they would in daylight.

e. 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 4-17). 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.

a. 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 [90-6].)

b. 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.

a. Communications. 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 may need to set up relay stations. "Radio skipping" happens often in cold weather areas. RATELOs often hear long-distance radio traffic on tactical FM networks.

b. Navigation. In snow-covered areas with flat terrain, pilots may 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 4-18). Whiteout conditions place extra demands on the landing site party.

c. Surface Conditions. 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 may also try to determine the degree of ground slope and whether or not obstacles lie under the cover of snow at each landing point.

d. Signalman. 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 sling load resembles other types of approach, but the pilot hovers at a higher altitude because of the load (A, Figure 4-18). He has a hard time judging the height of the sling load (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 4-18).

e. Sling Load Operations. The CH-47 requires a sling length of at least 60 feet. Other aircraft allow a shorter sling. Normally an aircraft hovers during hookup and liftoff with a sling load. Doing this above snow produces a snow cloud (B, Figure 4-18). 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.

f. Static Electricity. 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 6 provides additional information about the static probe).

g. Safety. 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 may 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.

a. Communications. 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.

b. Landing Sites. 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.

c. Navigation. 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 may 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.

d. Lights. The tactical situation may restrict the use of lights in nighttime jungle LZ operations.

e. Security. 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.

f. Liftoffs and Landings. 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. Since ground effects reduce the aircraft's lift efficiency, the pilot hovers as low as possible and lingers no longer than necessary.

a. Communications. 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 may 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 may provide air or ground relay or help deploy ground radio rebroadcast facilities.

b. Navigation. 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 may have to mark and man release points.

c. Landing Sites. 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.

d. Wind. 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.

e. Liftoffs. 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.

f. Landings. 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.

g. Safety. 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.

a. Communications. Mountainous terrain often limits or restricts communications. To maintain communications within the AO, aircraft may have to limit operations to the vicinity of the unit. Other aircraft can serve as radio relay stations. Pathfinder units may also have to set up radio relays at the RP, CCP, or both.

b. Wind. 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 may 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.

c. Density Altitude. 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.

d. Navigation. 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.

e. Landing Sites. Mountainous regions offer few, if any airfields for fixed-wing aircraft, and few LZs suitable for multiple helicopters.

f. Site Assessment. Pathfinders should determine the following information while reconnoitering and selecting a mountain site: