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

3. Trackline Multiunit Return (TMR). Two or more SRUs are used
in an abeam formation to afford greater width coverage along
track. See Figure 5-24.
Figure 5-24.
4. Trackline Multiunit Non-Return (TMN). This pattern is the
same as TMR except search terminates at the opposite end of
track from where it began. See Figure 5-25.
Figure 5-25.
C. Parallel Patterns (P) are best adapted to rectangular or square
areas and have straight search legs that are usually aligned parallel to
the major axis. Parallel patterns are normally used for large, fairly
level search areas, where only approximate initial position is known,
and when uniform coverage is desired. Special parallel circle patterns
are normally used for small underwater areas and have legs of adjacent
concentric circles.
1. Parallel Track Single-Unit (PS) is used by single SRUs for
searching rectangular areas and is mostly used by fixed-wing
aircraft. Search legs are oriented along the major axis,
providing longer legs and fewer turns. See Figure 5-26.
2. Parallel Track Multiunit (PM) provides accurate track spacing
and fast area coverage, and an increased safety factor for
aircraft over water. One SRU is designated as guide and
handles navigation, communications, and control. Turns at the
end of legs should be executed by signal from the guide.
Crosslegs are a distance equal to the track spacing multiplied
by the number of SRUs in the team (n). See Figure 5-27. Land
SRUs use procedures in Chapter 8.