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

fix errors (Fixe) listed in Table 5-2 may be assumed for
positions reported as navigation fixes (X=Fixe). If the means
of navigation on the distressed craft is unknown, the SMC
should assign error on the following basis:
a. 5 NM for ships, military submarines, and aircraft
with more two engines.
b. 10 NM for twin-engine aircraft.
c. 15 NM for boats, submersibles, and single-engine
aircraft.
2. If the position is determined from an FCC direction-finding
network, the fix error corresponds to the assigned
classification of the fix as follows:
Navigational Fix Errors
Class of Fix Fix Error
A 20 NM
B 40 NM
C 60 NM
TABLE 5-3. Dead Reckoning Errors
Type of Craft DRe
Ship 5 percent of the DR distance
Submarine (military) 5 percent of the DR distance
Aircraft (more than 2 engines) 5 percent of the DR distance
Aircraft (twin-engine) 10 percent of the DR distance
Aircraft (single-engine) 15 percent of the DR distance
Submersible 15 percent of the DR distance
Boat 15 percent of the DR distance
3. When the initially reported position is based on dead
reckoning (DR), an additional error is assumed for the
distance traveled since the last fix. The initial position
error is the sum of the fix error and DR error (DRe). Table
5-3 gives DRe which may be assumed for various types of craft.
D. SRU Error (Y) based on errors in SRU navigation accuracy,
should be considered by the SMC. Since SRUs maintain frequent fixes,
usually only Fixe is used. However, if an SRU uses DR navigation in the
search area, the SMC should be advised. The SMC then uses both Fixe and