text: Air Movement Plan
  Figure 12-2. Standard flight and landing formations
  12-12. The pathfinder chooses landing sites that have firm surfaces; are free of dust, sand, and debris that
  might create problems when disturbed byrotor wash; and are cleared ofobstacles. The landing site is laid
  out in a location where helicopters will not fly directly over aircraft on the ground. The layout of the site
  also depends on the landing space available, the number and type of obstacles, unit standard operating
  procedures, and prearranged flight formations. En route formation impacts how the formation lands,
  impactingloadingandoff-loadingofaircraft.(RefertoFM3-21.38formoreinformation.)
  TERRAIN FLIGHT MODES
  12-13. A specific en route flight altitude is not designated and is usually below the coordinating altitude.
  Factors affecting flight altitude include enemy, terrain, navigation, weather, flight distance, need for
  surprise, and pilot fatigue. Pilots may use one or some combination of the three terrain flight modes as
  dictatedbythemissionvariables.