Advanced Aviation Physiology and Health
Advanced Aviation Physiology and Health
The exam tests flight-environment pathology: decompression sickness, barotrauma, sensory illusions, acceleration and toxic exposure. Questions are applied: which illusion, which prevention, which priority.
Pressure, oxygen and decompression sickness
- Decompression sickness: nitrogen bubbles form when ambient pressure falls too fast after exposure to higher pressure (altitude, diving). Type I: joint and skin pain. Type II: neurological, respiratory (chokes), cardiovascular. Prevention: pre-oxygenation, slow ascent, avoid flying after diving, oxygen and descent for treatment.
- Barotrauma: ears (most common), sinuses, teeth, gastrointestinal tract. Equalise early and often; never force descent with a blocked ear.
- Hypoxia and hyperventilation still appear here; treat hypoxia with oxygen and descent, hyperventilation by breathing control.
Vision, hearing, acceleration and orientation
- Empty-field myopia: focus at about 1-2 m in a featureless sky; scan in sectors and focus far.
- Night vision: rods, off-centre viewing, dark adaptation; avoid white light and smoking.
- Noise: use headsets; hearing loss is cumulative. Communication failure may be insidious.
- Acceleration: plus-Gz pushes blood away from the head; G-LOC occurs without warning; AGSM and anti-G suit protect. Negative G causes red-out and discomfort.
- Illusions: somatogyral (spiral) from sustained rotation; somatogravic (false climb or descent) during acceleration; the leans from a slow bank. Trust instruments, not sensation.
- Motion sickness: mismatch between visual and vestibular input; treat with adaptation and avoid head movement.
- Toxic hazards: carbon monoxide, ozone, fuel vapour, hydraulic fluid; radiation: cosmic and solar, higher at altitude and latitude.
Worked example
On a dark go-around, the pilot accelerates and feels a strong pitch-up, so pushes forward. This is somatogravic illusion: linear acceleration stimulates the otoliths like a nose-up attitude. The reasoning: the correct response is to cross-check the attitude indicator and airspeed, not to trust the seat. Pushing forward can produce a dangerous dive.
Traps
Do not confuse decompression sickness with barotrauma; decompression sickness is bubble-mediated and systemic. Do not say G-LOC has a long warning phase. Do not describe the leans as a visual illusion only; it is vestibular. Do not claim carbon monoxide has a reliable smell. Do not treat all disorientation as avoidable by just looking outside at night.