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Pilot's Handbook of Aeronautical Knowledge
Aeromedical Factors

Health and Physiological Factors Affecting Pilot Performance

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Pilot's Handbook of Aeronautical Knowledge



Table of Contents

Chapter 1, Introduction To Flying
Chapter 2, Aircraft Structure
Chapter 3, Principles of Flight
Chapter 4, Aerodynamics of Flight
Chapter 5, Flight Controls
Chapter 6, Aircraft Systems
Chapter 7, Flight Instruments
Chapter 8, Flight Manuals and Other Documents
Chapter 9, Weight and Balance
Chapter 10, Aircraft Performance
Chapter 11, Weather Theory
Chapter 12, Aviation Weather Services
Chapter 13, Airport Operation
Chapter 14, Airspace
Chapter 15, Navigation
Chapter 16, Aeromedical Factors
Chapter 17, Aeronautical Decision Making




Signs and symptoms of altitude decompression sickness.
Figure 16-10. Signs and symptoms of altitude decompression sickness.

Altitude-Induced Decompression Sickness (DCS)
Decompression sickness (DCS) describes a condition
characterized by a variety of symptoms resulting from
exposure to low barometric pressures that cause inert gases
(mainly nitrogen), normally dissolved in body fluids and
tissues, to come out of physical solution and form bubbles.
Nitrogen is an inert gas normally stored throughout the
human body (tissues and fluids) in physical solution. When
the body is exposed to decreased barometric pressures (as in
flying an unpressurized aircraft to altitude, or during a rapid
decompression), the nitrogen dissolved in the body comes out
of solution. If the nitrogen is forced to leave the solution too
rapidly, bubbles form in different areas of the body, causing a
variety of signs and symptoms. The most common symptom is
joint pain, which is known as "the bends." [Figure 16-10]

What to do when altitude-induced DCS occurs:
• Put on oxygen mask immediately and switch the
regulator to 100 percent oxygen.
• Begin an emergency descent and land as soon as
possible. Even if the symptoms disappear during
descent, land and seek medical evaluation while
continuing to breathe oxygen.

• If one of the symptoms is joint pain, keep the affected
area still; do not try to work pain out by moving the
joint around.
• Upon landing seek medical assistance from an FAA
medical officer, AME, military flight surgeon, or
a hyperbaric medicine specialist. Be aware that a
physician not specialized in aviation or hypobaric
medicine may not be familiar with this type of medical
• Definitive medical treatment may involve the use of
a hyperbaric chamber operated by specially trained
• Delayed signs and symptoms of altitude-induced DCS
can occur after return to ground level regardless of
presence during flight

DCS After Scuba Diving
Scuba diving subjects the body to increased pressure, which
allows more nitrogen to dissolve in body tissues and fluids
[Figure 16-11] The reduction of atmospheric pressure that
accompanies flying can produce physical problems for scuba
divers. A pilot or passenger who intends to fly after scuba
diving should allow the body sufficient time to rid itself of
excess nitrogen absorbed during diving. If not, DCS due to
evolved gas can occur during exposure to low altitude and
create a serious inflight emergency.