There is little documentation on ricochet phenomenon except from
certain weapons testing ranges (usually larger than air crew training ranges).
Information received from Naval Weapons Center, China Lake, CA, is as follows:
For 20 mm ammunition fired at 10 to 30 degree attack angle on air-to-ground
targets where the target area contains rock, boulders, hard pm, or where
targets are hard, such as armored tanks, the maximum expected downrange
ricochet distance is 12,000 ft (3657.6 m) from center of target, the maximum
expected side-range ricochet distance is 4,000 ft (1219.2 m), from center of
target, and maximum expected ricochet height is 3,500 ft (1066.8 m).
Where the target area is loose sand, soft clay or a material that is
free from rocks, boulders, and large quantities of spent ammunition, the
maximum expected downrange ricochet distance is 9,000 ft (2743.2 m) from
center of target, the maximum expected side-range ricochet distance is
2,700 ft (823 m), and the maximum expected ricochet height is less than
3,500 ft. Current information should be obtained when designing ranges. The
use of frangible bombs has been tested, but economic or other factors may
preclude their general use on all ranges.
Siting. Aircraft ranges should be located within a maximum 100 ml
(160.9 km) distance from the supporting air installation.
Strafing Range. A strafing range is used for air-to-ground firing
Of aircraft weapons such as 20 mm automatic cannon.
Site. The strafing range shall consist of a restricted airspace
With a minimum radius of five nautical miles, and a surface-impact area
measuring 1 by 1/2 ml (1.6 km by 0.8 km) located in the center of the
restricted area. See Facility Plate No. 179-10, Sheet 1, for strafing range.
The restricted airspace is needed to encompass the flight pattern of high-
speed jet aircraft during approach, recovery, and circling for new approaches
to the target. The surface impact area should be sited in all areas approved
by Station ordnance officer and in a remote location where ricochets, strays,
and falling brass and links will not jeopardize surrounding property or
personnel. Periodically sanitizing the impact areas is required maintenance.
Targets. Design criteria for strafing targets vary according to
local training programs. See Facility Plate No. 179-10, Sheet 2, for
acoustiscore strafing target. Targets may consist of automatic recording
targets, simulated gun emplacements, aircraft, or portable target panels. For
a typical strafing target, see Facility Plate No. 179-10, Sheet 3.
18.104.22.168 Cease Fire Point. A cease-fire point for strafing runs shall be
indicated either by a 15 x 600 ft (4.57 x 183 m) white "foul" line on the
ground or by pylons (with height and color readily visible to pilots) spaced
600 ft apart. The foul line or pylons shall be on a line projected from the
control tower and perpendicular to the aircraft run-in line.