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

C. Multisensor search is either multiple SRUs searching with
different sensors or a single SRU searching with two or more sensors
simultaneously. While this can improve search performance of SRUs,
careful search planning and appropriate tactics are required to maximize
the contribution of all sensors and achieve the largest sweep width
possible.
650 SIGHTING AND IDENTIFICATION
651 Investigation Sightings
A. During a large search many objects other than the actual search
target may be sighted. Diverting from search to identify sighted
objects diminishes the uniformity of search area coverage regardless of
navigation accuracy. This will cause actual POD to be lower than
calculated POD. Tactics that minimize this effect should be used. If a
subsequent search leg will bring the SRU closer to the object, it may be
preferable to delay identification until then. Marking the positions of
targets of interest for identification should also be considered.
B. Objects sighted other than the actual search target may offer
clues that, if properly interpreted, lead to the location of survivors.
1. When a large vessel goes down suddenly, the scene may be
littered with considerable debris and a large oil slick,
usually traveling downwind of the origin. Boats and rafts
will usually be downwind of the debris. Persons in the water
may be found clinging to floating objects. Lifeboats from
large vessels are normally equipped with pyrotechnics and
emergency radios and may have power or sail. If more than one
boat is launched, they can be expected to be grouped, or tied
together, to make sighting easier. If the vessel was
abandoned before sinking, lifeboats, rafts, and personnel may
be upwind of the point of foundering, so SRUs should search
both upwind and downwind of an oil and debris area. In heavy
seas, survivors may also be moved by the seas in the direction
in which the seas are traveling.
2. An abandoned ship may drift faster than its survival craft.
In such cases, concentrated search upwind is recommended.
However, a half-sunken, loaded ship may drift more slowly than
a floating survival craft, even if a drogue is used, and may
also drift at a considerable angle off the prevailing wind
direction.
3. Small craft, such as yachts and fishing vessels, sometimes
carry only a small dinghy or raft. Others have only life
jackets. Boats or rafts from small craft have a limited
supply of visual detection aids. In the case of a maritime
search for survivors of an aircraft incident, scanners should
look for scattered wreckage such as oxygen bottles,
floorboards, seat cushions, and pieces of rafts. In some
cases there may be nothing but an oil slick.