text: Chapter 5
  Figure 5-12. Marking procedures for landing and pickup zones.
  CAUTION
  Not all chemical lights are visible at night, even through
  image-intensifying night vision devices. The FRIES master must
  coordinate with the pilots during the air mission brief to finalize the
  types and colors of chemical lights to use.
  LANDING POINT
  5-82. Each aircraft requires a circular landing point separate from those designated for other aircraft,
  and free of obstacles. Table 5-1 shows the minimum recommended landing point diameters (in meters).
  Table 5-1. Minimum recommended landing point diameters.
  Minimum
  Landing
  Aircraft Diameter
  Observation helicopters 25 meters
  UH-1, AH-1 35 meters
  UH-60, AH-64 50 meters
  Cargo helicopters 80 meters
  SURFACE CONDITIONS
  5-83. The surface of the PZ or LZ should allow clear visibility of the touchdown point. It should be free
  of landing hazards such as blowing sand, dust, or snow. It should contain no obstacles that could damage
  landing aircraft such as trees, stumps, or large rocks. The surface must be firm enough to support the
  traffic. It should have adequate drainage to allow rainfall to run off. Unacceptable levels of CBRN
  contamination can preclude the use of an area. If part of an area falls short for any reason, that part is not
  used.
  GROUND SLOPE
  5-84. Generally, if the ground slopes 0 to 6 percent, then the pilot should land upslope. If the ground
  slopes 7 to 15 percent, then he should land side slope. Over 15 percent, he should not touch down at all,
  but he may, if conditions allow, hover to drop off or pick up personnel or equipment.