text: Chapter 4
  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.