AIM Text
- Carbon monoxide is a colorless, odorless, and tasteless gas contained in exhaust fumes. When breathed even in minute quantities over a period of time, it can significantly reduce the ability of the blood to carry oxygen. Consequently, effects of hypoxia occur.
- Most heaters in light aircraft work by air flowing over the manifold. Use of these heaters while exhaust fumes are escaping through manifold cracks and seals is responsible every year for several nonfatal and fatal aircraft accidents from carbon monoxide poisoning.
- A pilot who detects the odor of exhaust or experiences symptoms of headache, drowsiness, or dizziness while using the heater should suspect carbon monoxide poisoning, and immediately shut off the heater and open air vents. If symptoms are severe or continue after landing, medical treatment should be sought.
Source: FAA Aeronautical Information Manual · current edition · paragraph 8-1-4.
The short answer
This AIM section is advisory FAA guidance on carbon monoxide poisoning in flight. It explains that carbon monoxide is a colorless, odorless, tasteless exhaust gas that reduces the blood's ability to carry oxygen, causing hypoxia, and that cracked manifold heaters are a recurring cause. It supports the pilot's airworthiness and safe-operation duties under 14 CFR 91.
Research Notes
Common Questions
What are the symptoms of carbon monoxide poisoning in flight?
The section lists headache, drowsiness, or dizziness, often along with the odor of exhaust while using the heater. Because CO reduces the blood's oxygen-carrying ability, the effects of hypoxia occur.
What should a pilot do if carbon monoxide poisoning is suspected?
Per this guidance, immediately shut off the heater and open air vents. If symptoms are severe or continue after landing, medical treatment should be sought.
Why are light-aircraft cabin heaters a carbon monoxide risk?
Most light-aircraft heaters work by air flowing over the manifold. When exhaust fumes escape through manifold cracks and seals, that heated air can carry carbon monoxide into the cabin, causing accidents every year.