Carbon monoxide (CO) is odourless and tasteless. It is produced by incomplete combustion of fuel and when breathed it enters the bloodstream and mixes with haemoglobin (the part of red blood cells that carry oxygen around your body) to form carboxyhaemoglobin. When this happens, the blood loses its ability to carry oxygen, causing cells to fail and die, effectively producing the effects of hypoxia — mainly a headache, drowsiness, or dizziness.
Other symptoms can include impaired vision, feeling and being sick, tiredness and confusion, stomach pain, shortness of breath and difficulty breathing, and recovery can take up to 24 hours.
Many light aircraft heaters utilising air flowing over the exhaust manifold to provide cabin warmth, fumes escaping through manifold cracks and seals is one of the main sources of such poisoning.
The immediate remedial action is to shut off the heater, open the air vents and, if necessary, land. If the symptoms are severe, or continue after landing, it’s best to seek medical treatment.
A BGA club recently reported that their tug aircraft had a carbon monoxide (CO) leak from an exhaust defect that was picked up by the active CO detector in the cockpit. As a result, the fault was resolved without risk to the pilot, who otherwise would likely have been unaware of the danger.
Carrying an active carbon monoxide detector in the cockpit can provide an effective early alert to the risk of carbon monoxide being present due to their ‘attention getting’ functionality. There is a large range of advanced electronic devices available, both portable and fixed. These provide audible alarms and/or digital readouts and cost anything from a few tens of pounds to several hundreds, all of which should, if properly set up effectively mitigate the risk.