Carbon monoxide in general aviation

Public Consultation 2024

In February 2024 the CAA launched a 4-week public consultation seeking stakeholder views on various topics associated with carbon monoxide (CO) in piston engine aircraft. The consultation received a total of 271 responses.

A summary of the responses received, the decisions made, as well as the next steps being taken can be found in the Comment Response Document and on the consultation page.

The CAA took into account the comments received in the consultation and will be issuing a Safety Directive requiring a functioning active CO detector to be present in specified piston engine aircraft when operating with passengers who do not possess a recognised pilot qualification. The directive will be published in late August 2024 and will come into effect from 1 January 2025.

What is Carbon Monoxide poisoning and why is it a risk?

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.

How to reduce risk of carbon monoxide poisoning

While most, if not all, pilots check their engine(s) and exhausts before flight for just such an issue, it’s worth remembering that if the aircraft heater hasn’t been used for many months the whole heating system should be checked even more thoroughly before a flight where it’s likely to be used.
Ensuring thorough checks are made when the aircraft is in for maintenance and carrying an active carbon monoxide detector will help mitigate the risks of carbon monoxide poisoning.

What is an active carbon monoxide detector and the benefits of carrying one

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.

Survey - 2023

On, 8 June 2023 we launched a further short survey asking about your experience of active carbon monoxide detectors. The findings gathered from this survey have been released and will help to shape the future use of these devices and how they could be used in piston engine aircraft.

Evidence to date indicates that active CO detectors capable of alerting pilots via aural and/or visible warnings are a net safety benefit to pilots and their passengers.

While the risk of CO poisoning may be known and understood by many GA pilots, the same cannot be said for consumers and third parties generally, who may fly in piston engine aircraft on a commercial or recreational basis.

Survey - 2021

On, 14 July 2021 we launched a short survey asking about your experience of active carbon monoxide detectors. The feedback we have received helps us to understand how these devices are already used and how they generally perform within the GA environment. The findings of the survey are available here.

Active carbon monoxide detector general aviation trial

In September 2021, we launched an active CO detector trial with the UK GA community. The trial focuses on a monthly survey issued to registered members. By working closely with GA pilots who currently fly with active CO detectors on a voluntary basis, we hope to understand how these devices perform over the course of a full flying season in a variety of aircraft and what the experience of using these devices has been. The trial will also help us understand to what extent carbon monoxide affects UK GA.

Quarter 1 Summary (September - November 2021)

Quarter 2 Summary (December 2021 - February 2022)

Quarter 3 Summary (March 2022 - May 2022)

Quarter 4 Summary (June 2022 - August 2022)

Carbon Monoxide Detector Trial Summary Report

For any questions or queries on the trial or the work of the CAA on this topic please contact CODE@caa.co.uk