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

a. The effects of time on task vary with SRU type.
Units capable of rotating scanners into rest periods can be
expected to reach a steady state of performance after initial
degradation. Other SRUs will probably decline steadily in
performance up to the limits of on scene endurance.
b. At night, scanner relief should be carried out with
some caution as approximately 30 minutes is necessary for eyes
to become dark adapted. Personnel should not be rotated
directly from lighted parts of the SRU to lookout positions.
c. Frequent light snacks and coffee, together with a
reasonable amount of conversation between observers, tends to
reduce fatigue.
d. In aircraft, unstabilized binoculars rapidly cause
eye fatigue and should be used only to check sightings made by
the naked eye. On steadier and slower platforms, binoculars
are useful for scanning.
e. "First-light" searches, although sometimes necessary,
have a detrimental effect on crew search effectiveness.
5. Motivation affects the performance of the entire crew. During
early stages of a search, motivation is high. After fatigue
sets in and hope of locating survivors decreases, motivation
can become a problem. Maintaining high motivation during the
search is the responsibility of the SRU commander. All
members of the crew should be made to realize they are
important parts of the
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