By Adrian McConnell, Head of Charitable Operations at CO Research Trust.

On 21st January 2019 the professional footballer Emiliano Sala and pilot David Ibbotson crashed in a light aircraft while travelling from Nantes in France to Cardiff. Both sadly died. Toxicology tests found levels of carbon monoxide (CO) within the footballer’s body was enough to cause symptoms such as seizure, unconsciousness and heart attack.

Even without physical examination of the wreckage it seems likely that CO poisoning played an important role in the crash. In the last 20 years there have been 87 air accidents relating to CO poisoning reported in the UK, USA and Australia.

The most common sources of CO in general aviation are exhaust gases from piston-driven engines. There are, however, other sources relevant to the wider sector including the exhaust gases from turbine engines, auxiliary power units, airside vehicles, ground servicing equipment and from combustion of materials during emergencies.


Should these gases find their way into the aircraft interior they may be inhaled by the pilot, crew or passengers. The resulting symptoms can vary from nothing noticeable to in the worst cases, a catastrophic accident with the potential for significant loss of life and collateral damage.

Our vision is a world where people are not exposed to CO. We believe it is vital we identify the key questions that need to be answered so that safety can be improved in this area.

In 2020 the CO Research Trust board approved funding for a project by a team at Queen Mary University London, to investigate the risks of CO poisoning in the general aviation sector.

Queen Mary University of London

The general aviation sector covers all civil aviation operations, with the exception of commercial air transport. General aviation represents the private transport component of aviation.

The primary objective of the project was to assess the status, best practices and risks associated with CO poisoning in this sector.

Symptoms of CO poisoning

Symptoms of CO poisoning can be flu-like. However, unlike flu, CO poisoning does not cause a high temperature. A headache is the most common symptom of mild CO poisoning, but other symptoms include dizziness, feeling sick, tiredness and confusion, stomach pain and shortness of breath. Loss of consciousness tends to follow, unless the source of exposure is removed.

This is particularly problematic within the general aviation sector as symptoms of CO poisoning are not always obvious. The onset of drowsiness can happen quickly and unless immediate action is taken to reduce exposure and reverse the concentration of CO in the blood, unconsciousness is inevitable.

Pilots at the greatest risk from CO poisoning are those flying small piston-powered aircraft solo.

Because of the generic nature of the symptoms of CO poisoning, it’s possible that flight crew and passengers may have been exposed to low levels of CO but identified that the cause of their symptoms were due to air-sickness or fatigue. Once the source of CO is removed, i.e. they leave the aircraft, symptoms will have subsided, leading them to confirm their mis-diagnosis.

This means that incidents may not be reported and that opportunities to identify potential maintenance issues with aircraft get missed.

Causes of CO poisoning in aviation

As mentioned, the most common sources of CO in general aviation are exhaust gases from piston-driven engines. Poor maintenance or damaged aircraft can result in CO entering the cabin and flight deck. This can happen directly through open doors and hatches, or it can enter via the air-conditioning system.

One of the primary aims of the project was to further the understanding of these issues. However, it was also to raise awareness directly among key stakeholders in the general aviation sector.

Prevention of CO poisoning in aviation

As we approach the publication of the White Paper, we are keen to begin engaging with the aviation community to open discussions about how to solve this largely preventable problem.

We recognise that raising awareness of this issue is the best protection. Increasing awareness of the steps that can be taken to prevent exposure to CO is key to saving lives.

The steps to prevent CO exposure include.

- Detection and warning - use of an audible CO alarm

- Maintenance - particularly of the heating and ventilation system

- Awareness - if pilots are aware of the symptoms, they can take immediate action should they suspect exposure

Next steps

One of the secondary objectives of this project was to identify areas and potential partners for further research work. On Thursday 23rd September Dr Andrew Spowage of Queen Mary University of London presented his findings from the White Paper titled "Risks of CO in General Aviation." This was the first in the Lecture Series launched by us to help share the findings of research projects that we are funding.

Below are Dr Spowage's power point slides.

The full presentation with commentary can be seen here.

We hope that sharing this lecture will help to raise awareness of this important issue and start to move the conversation forward in terms of how to work towards prevention.

We were delighted with the response from the aviation industry so far. We are excited to share the news that the UK Civil Aviation Authority have launched an Active Carbon Monoxide (CO) Detector Trial. This is open to any member of the general aviation community and involves them completing a short monthly survey. More details of this trial can be found here.

This project has been particularly timely as the COVID-19 crisis has seen much of fleet grounded for extended period which may lead to aircraft maintenance and pilot proficiency issues. Furthermore, the UK's exit from the European Aviation Safety Agency has led to uncertainties within the community and interest from UK based authorities in forming new partnerships.

Following this event we are working with industry partners to look at ways we can raise awareness and find solutions to this resolvable issue.

Adrian McConnell, Head of Charitable Operations, The CO Research Trust
Adrian McConnell, Head of Charitable Operations, The CO Research Trust