The partial incapacitation of a pilot flying a Cessna 402C with 5 passengers on board again highlights the dangers of carbon monoxide (CO) and the importance of carrying an active warning CO detector.
An ATSB Occurrence Brief details that prior to departure from Jandakot Airport, Western Australia, in April 2026, the pilot used the aircraft’s heater to defrost the windshield for approximately 7 minutes and recalled turning off the heater before take-off.
Following the aircraft’s departure and while in the cruise, the pilot began feeling light‑headed and ‘zoned out’ momentarily. They then observed the passive carbon monoxide detection placard had changed colour, indicating that CO was present.
The pilot immediately opened all available air vents, opened the cabin air controls, re‑confirmed the heater was off, and diverted the aircraft to Merredin, about 240 km east of Perth.
The pilot continued to self-monitor during the descent, and determined their condition was not deteriorating. None of the passengers reported any ill effects of CO.
The aircraft landed safely, and a subsequent inspection found the heater was defective, damaged, and potentially incorrectly reinstalled.
“CO is a colourless and odourless gas, and its insidious presence may not be detected until the physical symptoms and cognitive effects present themselves,” ATSB Chief Commissioner Angus Mitchell said.
“Disposable CO chemical spot detectors, commonly used in general aviation aircraft, have known limitations. They’re a passive device relying on the pilot to regularly monitor for a change in colour.”
For that reason the ATSB’s Know CO campaign encourages pilots of piston engine aircraft to use an active warning CO detector to help identify CO exposure early and reduce the risk of incapacitation.
“If your aircraft is not fitted with an active device, we encourage pilots to carry a personal active warning CO detector,” Mr Mitchell concluded.
“The presence of CO in the cabin can adversely affect a pilot’s ability to control their aircraft which could lead to fatal consequences. If you haven’t, fit your aircraft with – or carry – an active warning CO detector, and Know CO.”
More information about the Know CO campaign can be found here.