Carbon Monoxide Poisoning

AIM ¶ 8-1-4 — Carbon Monoxide Poisoning

AIM 8-1-4 explains carbon monoxide poisoning in flight: causes, symptoms, and pilot response. Key checkride topic for student pilots.

In Plain English

Carbon monoxide (CO) is a colorless, odorless, tasteless gas found in engine exhaust fumes. Even small amounts breathed over time reduce the blood's ability to carry oxygen, producing the same dangerous effects as hypoxia.

This matters because most light aircraft cabin heaters work by routing fresh air over the exhaust manifold before sending it into the cabin. If the manifold has cracks or leaking seals, exhaust gases — including CO — can enter the cockpit along with the heated air. Every year, this causes several fatal and nonfatal accidents.

Watch for these warning signs while using the heater:

Smell of exhaust in the cabin
Headache
Drowsiness
Dizziness

If you suspect CO poisoning:

Shut off the heater immediately
Open the fresh air vents
Land as soon as practical
Seek medical treatment if symptoms are severe or continue after landing

Many pilots also carry a CO detector (chemical spot or electronic) as a low-cost backup — a recommended practice, not a regulatory requirement.

AIM Source Text

FAA AIM ¶ 8-1-4

8-1-4. 8-1-4. Carbon Monoxide Poisoning in Flight 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.

Oral Exam Questions a DPE Might Ask

Q1What are the characteristics of carbon monoxide and why is it dangerous in flight?

Per AIM 8-1-4, carbon monoxide is a colorless, odorless, and tasteless gas found in exhaust fumes. Even minute quantities breathed over time significantly reduce the blood's ability to carry oxygen, producing the effects of hypoxia.

Q2How does carbon monoxide typically enter the cabin of a light aircraft?

Per AIM 8-1-4, most light aircraft heaters work by flowing air over the exhaust manifold. If exhaust fumes escape through cracks or seals in the manifold, they can enter the cabin through the heater system, causing CO poisoning.

Q3What symptoms indicate possible CO poisoning, and what action should you take?

Per AIM 8-1-4, symptoms include the odor of exhaust, headache, drowsiness, or dizziness while using the heater. The pilot should immediately shut off the heater, open the air vents, and seek medical treatment after landing if symptoms are severe or persist.

Related Paragraphs in AIM Chapter 8

Hyperventilation in Flight