text: Drop Zones
  Figure 6-19. Computation of circular drop zone.
  RANDOM POINTS OF IMPACT
  6-132. When mission requirements dictate, the DZSTL may use the RPI placement option. He has two
  options:
  Option 1
  6-133. The mission commander notifies the DZSTL at least 24 hours in advance that RPI placement will
  be used. When the DZ is established, the DZSTL randomly selects a point on the DZ and establishes that
  point as the PI for the airdrop. The DZSTL ensures that the DZ meets the minimum size requirements for
  the type of load and that the entire DZ falls within the surveyed boundaries.
  Option 2
  6-134. The mission commander or supported force commander may request the DZ established with the
  PI at a specific point on the DZ. Requests should be made at least 24 hours in advance. The requestor
  ensures that the DZ meets minimum size criteria for the type of load, and that the entire DZ falls within the
  surveyed boundaries.
  MULTIPLE POINTS OF IMPACT
  6-135. An MPI airdrop is authorized if everyone involved has been properly briefed. An MPI airdrop is
  the calculated dispersal, both laterally and longitudinally, of airdropped loads to predetermined locations
  on a DZ. The DZ must meet the minimum size requirements for each PI, and the DZSTL must provide the
  precise location of each PI to the aircrews. Offset PIs are surveyed PIs 250 yards left and right of the
  surveyed PI. The DZ width must be increased to meet the distance criteria from the DZ edge to the PI. This
  manner of placement reduces the effects of wake turbulence across the DZ.