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AIM

10/12/17

8−1−3

Fitness for Flight

easily committed to memory is being distributed by

the FAA in the form of a wallet-sized card.

i. PERSONAL CHECKLIST. I’m physically

and mentally safe to fly; not being impaired by:

I

llness

M

edication

S

tress

A

lcohol

F

atigue

E

motion

8−1−2. Effects of Altitude

a. Hypoxia.

1. Hypoxia is a state of oxygen deficiency in the

body sufficient to impair functions of the brain and

other organs. Hypoxia from exposure to altitude is

due only to the reduced barometric pressures

encountered at altitude, for the concentration of

oxygen in the atmosphere remains about 21 percent

from the ground out to space.

2. Although a deterioration in night vision

occurs at a cabin pressure altitude as low as

5,000 feet, other significant effects of altitude

hypoxia usually do not occur in the normal healthy

pilot below 12,000 feet. From 12,000 to 15,000 feet

of altitude, judgment, memory, alertness, coordina-

tion and ability to make calculations are impaired,

and headache, drowsiness, dizziness and either a

sense of well-being (euphoria) or belligerence occur.

The effects appear following increasingly shorter

periods of exposure to increasing altitude. In fact,

pilot performance can seriously deteriorate within

15 minutes at 15,000 feet.

3. At cabin pressure altitudes above 15,000 feet,

the periphery of the visual field grays out to a point

where only central vision remains (tunnel vision). A

blue coloration (cyanosis) of the fingernails and lips

develops. The ability to take corrective and protective

action is lost in 20 to 30 minutes at 18,000 feet and

5 to 12 minutes at 20,000 feet, followed soon

thereafter by unconsciousness.

4. The altitude at which significant effects of

hypoxia occur can be lowered by a number of factors.

Carbon monoxide inhaled in smoking or from

exhaust fumes, lowered hemoglobin (anemia), and

certain medications can reduce the oxygen-carrying

capacity of the blood to the degree that the amount of

oxygen provided to body tissues will already be

equivalent to the oxygen provided to the tissues when

exposed to a cabin pressure altitude of several

thousand feet. Small amounts of alcohol and low

doses of certain drugs, such as antihistamines,

tranquilizers, sedatives and analgesics can, through

their depressant action, render the brain much more

susceptible to hypoxia. Extreme heat and cold, fever,

and anxiety increase the body’s demand for oxygen,

and hence its susceptibility to hypoxia.

5. The effects of hypoxia are usually quite

difficult to recognize, especially when they occur

gradually. Since symptoms of hypoxia do not vary in

an individual, the ability to recognize hypoxia can be

greatly improved by experiencing and witnessing the

effects of hypoxia during an altitude chamber

“flight.” The FAA provides this opportunity through

aviation physiology training, which is conducted at

the FAA Civil Aeromedical Institute and at many

military facilities across the U.S. To attend the

Physiological Training Program at the Civil

Aeromedical Institute, Mike Monroney Aeronautical

Center, Oklahoma City, OK, contact by telephone

(405) 954−6212, or by writing Aerospace Medical

Education Division, AAM−400, CAMI, Mike

Monroney Aeronautical Center, P.O. Box 25082,

Oklahoma City, OK 73125.

NOTE−

To attend the physiological training program at one of the

military installations having the training capability, an

application form and a fee must be submitted. Full

particulars about location, fees, scheduling procedures,

course content, individual requirements, etc., are con-

tained in the Physiological Training Application, Form

Number AC 3150−7, which is obtained by contacting the

accident prevention specialist or the office forms manager

in the nearest FAA office.

6. Hypoxia is prevented by heeding factors that

reduce tolerance to altitude, by enriching the inspired

air with oxygen from an appropriate oxygen system,

and by maintaining a comfortable, safe cabin

pressure altitude. For optimum protection, pilots are

encouraged to use supplemental oxygen above