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

APPENDIX D. MARITIME SWEEP WIDTH FACTORS AND TABLES
A. Determining the Uncorrected Sweep Width. Locate the table in
VOL. II, Chapter 4, for the type of SRU (fixed-wing, helicopter, vessel,
or small boat). For aircraft, enter the column for the appropriate
altitude and visibility. For surface craft, enter the column for the
appropriate visibility. Read down this column to the target type that
most closely describes the search object. This value is the uncorrected
sweep width and should be adjusted for weather, fatigue, and aircraft
speed. Interpolate as necessary.
B. Correcting for Weather. Weather has an impact on search
effectiveness, and for small targets the reduction is substantial. Use
Table D-1 to determine the weather correction factor (if conditions of
both columns apply, use correction factor in right column).
TABLE D-1. Weather Correction Factor
Winds > Winds >
15 Kts 25 Kts
Target Type Seas 2-3 ft Seas > 4 Ft
Person in water, or
< 30-Ft Length Boat 0.5 0.25
Other Targets 0.9 0.9
C. Correcting for Fatigue. The sweep width tables are adjusted
for a "normal" amount of crew fatigue. If feedback from on scene SRUs
indicates search crews were excessively fatigued, reduce sweep width
values by 10 percent (multiply by 0.9).
D. Correcting for Search Aircraft Speed. Enter the Speed
Correction Table (Table D-2) with aircraft type (fixed-wing or
helicopter) and the speed flown. Read down the column to the search
object. This value is the speed correction. Interpolate as necessary.
There is no speed correction for surface SRUs.
E. Calculating Corrected Sweep Width. The final sweep width is
found as follows:
Corrected Sweep Width = (Uncorrected Sweep Width) x (Weather
Correction) x (Fatigue Correction) x (Speed Correction)
Sweep Width Example: An SRU flown at 1000 feet and 150 knots is
searching for a 26-foot sail boat. Winds are 20 knots with 2.5-foot
seas. Visibility is 20 miles. The SRU commander determines that the
crew is unusually fatigued.
Step 1: From the Fixed-Wing sweep width tables find the column for
1000-ft altitude and 20-mile visibility. Read down the column
TABLE D-2. Search Aircraft Speed Correction Table
D-1