text: 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).