JP 3-50 National Search and Rescue Manual Vol I - US Navy

with reasonable accuracy.
516 Minimax Solution
A. When one or more of the drift variables cannot be accurately
determined, the minimax solution can be used. It is usually used in
ocean search planning when drift time or speed of the object is unknown.
B. Many situations, particularly target uncertainty, may require a
minimax calculation. The SMC may be unsure whether survivors are still
aboard a vessel or have abandoned it, and ships, rafts, and persons in
the water have varying drift rates and divergence factors. Doubt about
injuries will complicate determining the distance people could move.
C. The SMC should select the variable with the greatest impact on
drift and solve for datum using the possible extremes, such as the
faster speed of an unballasted raft and the slower speed of a halfswamped
boat. This establishes the maximum and minimum drifts. Datum
minimax is half way between these points, ensuring that the most
probable position is closest to the center of the search area. See
Figure 5-8.
D. A minimax solution might be used if there is any doubt about
the following information:
1. For aircraft:
a. Altitude of parachute opening.
b. Point along a DR track or planned route where the
aircraft went down.
2. For inland persons:
a. Distance a lost child could travel.
b. Whether travel-inhibiting injuries have occurred.
3. For maritime situations:
a. Time a craft has been adrift.
b. Time local winds shifted.
c. Direction or speed of a drifting object.
d. Only known factor is the direction of a flare
sighting.