Where There’s Smoke…There’s Trouble!

April 26, 2022
April 26, 2022 Jean Diaz

No doubt about it: smoke and fumes in the cockpit create an acute medical emergency for pilots and potentially for their passengers. Here’s what you need to know.

Carbon Monoxide

Smoke is a direct irritant for the eyes, mucous membranes of the nose and mouth, and lungs. Carbon monoxide (CO) is present in both smoke from fires and in engine exhaust gases (incomplete combustion), so a leak in the manifold can surreptitiously introduce CO into the cabin air. This is particularly problematic in single engine aircraft as exhaust gases are the source of cabin heat. Burning plastics also release CO at high levels. Regardless of the source, you should know that CO is odorless, colorless, and dangerous. A CO detector is a worthwhile investment and standard in many new aircraft.

If there is a fire, take the necessary steps as outlined in the AFM/POH to avoid exposure. Even low levels of CO are dangerous as CO binds to hemoglobin over 200 times greater than oxygen does. This means that CO effectively blocks the hemoglobin molecule, to which it is bound, from transporting oxygen from your lungs to the rest of your body. With continued exposure to CO, less and less hemoglobin is available for oxygen transport and your breathing becomes less and less effective. CO poisoning causes headaches, nausea, dizziness, fatigue and eventually mental impairment and death.

The immediate remedy is to remove yourself from the source as soon as possible. However, symptoms can persist even when the cabin has been vented or source isolated. While fresh air helps, more rapid clearing is accomplished by increasing the oxygen percentage of the air you inhale. A nasal cannula will help, but a full-face mask with 100 percent oxygen is preferable.

Please note that this advice is not intended to teach you how to treat yourself, but rather to provide self-aid steps pending definitive medical care. Once on the ground, call 911 for assistance. In the case of severe CO poisoning, you might need hyperbaric treatment. The 911 operator can help or you can call the Divers Alert Network at either (919) 684-2948 or (800) 446-2671. A hospital emergency room should also be able to assist you.

Carbon Dioxide

Fumes can be a product of combustion or can result from cargo contents. A common and potentially dangerous gas is carbon dioxide (CO2). CO2 is a product of complete combustion and is nearly odorless and colorless. It is also a product of respiration and will build up if the ventilation is poor.

Another source is “dry ice,” which is frozen CO2. Dry ice is often used for long distance transport when items must be kept frozen. Cargo airliners have made emergency evacuations when CO2 levels rose in the aircraft from sublimation. Be extra cautious if you are using dry ice for cooling, such as for meat and/or fish obtained on a vacation trip. When possible, carry it in a baggage compartment outside the cabin and always ensure good ventilation.

As with CO, symptoms of CO2 poisoning include fatigue, headache, and cloudy thinking. You need to remove yourself from the source as quickly as possible. Recovery is rapid as, unlike CO, CO2 does not have a high affinity to hemoglobin, and clears rapidly once removed from the source.

Smoke and fumes in the cockpit have caused many cases of impairment/incapacitation. Do not forget that in an emergency you can request priority handling from ATC. Just make sure you request assistance promptly as symptoms can progress rapidly.

Finally, do not ignore the problem: the best place to sort out CO/CO2 symptoms is on the ground. Once you have landed, you should have a bias toward seeking medical attention, as your judgment to determine the need for it is frequently impaired.

Source: https://www.faa.gov/newsroom/safety-briefing/faa-safety-briefing-septemberoctober-2019