(1) At 12,000 to 15,000 feet (several hours): fatigue, drowsiness,
headache.
(2) At 15,000 to 18,000 feet (½ to 1 hour):
False sense of well being
Overconfidence
Narrowing of field of attention
Faulty reasoning
Poor judgement
Loss of self-criticism
Clumsy
Blurring and double vision
Decreased hearing
Poor memory
May pass out
(3) Above 18,000 feet:
Symptoms come on faster
Loss of muscle control
Loss of awareness of lapse of time
Loss of judgment and self-criticism
Loss of memory and ability to think
Loss of vision and hearing
Purposeless movements, repeated over and over
Emotional outbursts--hysteria, crying, laughing, anger
Loss of consciousness eventually:
at 26,000 feet 4 to 6 minutes
at 28,000 feet 2 to 4 minutes
at 30,000 feet 1 to 2 minutes
at 38,000 feet 30 seconds or less
The above varies with different individuals.
(4) Loss of night vision.
Night vision is reduced to one-half at 12,000 feet without
oxygen. Breathing oxygen restores it to normal.
(5) Breathing oxygen raises your ceiling.
ALTITUDE %OXYGEN EQUIVALENT
FEET BREATHED LEVEL (feet)
18,000 60 ground
26,000 85 ground
30,000 100 ground
33,000 100 8,000
38,000 100 12,000
44,000 100 22,000