FAA Sport Pilot Airplane (SPA)Human Factors and ADMHard
A pilot flying a fabric-covered airplane with a cabin heater notices a mild headache and drowsiness during a long cross-country flight. Exhaust fumes leaking into the cabin are suspected. What is the most probable source of this hazard?
- AExcessive cabin humidity
- BNitrogen buildup from the fuel system
- CCarbon monoxide from a cracked exhaust manifold or muffler
- DOzone contamination at altitude
Show answer & explanationAnswer & explanation
Correct answer: C. Carbon monoxide from a cracked exhaust manifold or muffler
Carbon monoxide poisoning commonly occurs in aircraft with heaters that draw warm air across the exhaust manifold; a crack or leak allows CO to enter the cabin, causing headache, drowsiness, and impaired judgment.
Why the other options are wrong
- A. Cabin humidity does not cause headache and drowsiness in this manner.
- B. Nitrogen buildup is not a typical hazard from aircraft exhaust systems.
- D. Ozone exposure is associated with high-altitude jet operations, not exhaust leaks in light aircraft.
Carbon Monoxide Poisoning
A toxic condition caused by inhaling carbon monoxide, often from cracked exhaust systems venting into aircraft cabin heaters, which binds to hemoglobin and blocks oxygen transport.
- Common source: heater exchangers near a cracked exhaust manifold
- Early symptoms include headache and drowsiness; later symptoms include cherry-red skin and loss of muscle control
- Colorless, odorless gas, making detectors or awareness essential
Memory trick: Headache, Haze, Handicap, Hue — the CO symptom ladder.