Figure 1-40.—Survivability of a person in water.
Anti-immersion suits are worn by aircrew
personnel to retain body heat if the aircrew must ditch in
the water. Unfortunately, anti-immersion gear is bulky
and hot, and aircrews prefer not to wear the gear. When
environmental conditions indicate usage is required,
shipboard Aerographers routinely include in flight
weather briefings the recommendation that aircrews use
anti-immersion suits. This recommendation should
also be included in shore-station briefings for over-
water flights. Navy and Marine Corps observers
usually provide the necessary information to the briefer,
based on their observations of the environmental
conditions.
Guidance for anti-immersion suit usage by aircrews
is given in OPNAVTNST 3710.7, NATOPS General
Flight and Operating Instructions. Anti-immersion
suits or pressure suits with thermal undergarments must
be worn when the coldest water temperature in the
mission area is
50°F or if the coldest wind chill
equivalent temperature on the (water) surface during
the mission is
32°F. When the water temperature is
>50°F but
60°F, antiexposure undergarments must be
worn, but the determination to wear anti-immersion
suits is made by the commanding officer. His or her
determination should be based on the length of time
required to respond with rescue assets to a ditch site,
ranging from 1 hour at 50°F to 3 hours at 60°F. With
water temperatures above 60°F, anti-immersion gear is
not required.
Navy and Marine Corps weather observers
routinely provide various values and indicators that are
used to gauge the effects of hot and cold environments
on personnel. These values are computed from
observed measurements made during surface weather
observations. All observers should be aware of the
effects of heat and cold on the human body, and should
be able to calculate the various indicators upon request.
Weather affects the performance of equipment as well
as personnel. In the next section, we consider aircraft
performance in changing weather conditions.
Q86.
Q87.
Q88.
Q89.
Q90.
Q91.
REVIEW QUESTIONS
What term describes the inability of the body to
get rid of excess heat fast enough to maintain an
internal temperature balance?
Define the term "relative humidity."
Given an air temperature of 90°F and a relative
humidity of 65%, what is the apparent
temperature?
What effects does the Wet-bulb Globe
Temperature index (WBGT) take into
consideration?
What is meant by the term "wind chill factor"?
What is the survival chance given a seawater
temperature of 15°C and an immersion time of 3
hours.
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