On 21 January this year (2019) footballer Emiliano Sala was killed when the Piper Malibu aircraft in which he was flying (from Nantes, France to Cardiff) crashed into the English Channel. The accident was widely reported at the time, along with all sorts of speculation about the cause. There has also been a lot of press about the licencing status of the pilot, David Ibbotson, who was also killed.

Today I read this article on the BBC news website, which reported that the autopsy on Sala’s body – which was recovered from the water in February – showed a carboxyhaemoglobin level of 58%. That’s the chemical formed in the blood when carbon monoxide gas is breathed in, and the carbon monoxide combines irreversibly with the haemoglobin in the blood preventing the transport of oxygen from the lungs around the body. According to the BBC’s sources, 58% is enough to cause seizures and heart stoppage. Anything above 50% is typically fatal in short order. Although Mr. Ibbotson’s body was not recovered it’s not a leap to conclude that if the passenger in the aircraft was subjected to such a disabling level of carbon monoxide, so was the pilot.

What really caught my eye was the comment from the BBC’s expert, Terry Tozer, billed as “retired pilot and aviation safety commentator”. According to the BBC, “Mr Tozer said he had never encountered anything similar before and would not expect carbon monoxide poisoning to be a big risk on such an aircraft.”

If Mr. Tozer had spent any time as an owner or operator of a single engine piston aircaft (like the Piper Malibu in question) with a Canadian registration, he would be familiar with Airworthiness Directive CF90-03R2 originally issued by Transport Canada in 1990 to require an annual (or more frequent) inspection of all exhaust heat exchangers used to heat cabin air by passing air from the outside through a metal jacket that surrounds part of the exhaust system. Any crack in the exhaust there can easily allow carbon monoxide to percolate into the cabin air, and that can lead to pilot incapacitation over time, with predictable results.

The Airworthiness Directive applies only to Canadian aircraft, of which the accident plane was not one. That airplane was in fact registered in the United States. We don’t have any information about the maintenance and inspection regime of that aircraft; but we can say that such a heat exchanger inspection was not mandatory for it under this purely Canadian scheme.

Obviously when people die in an aircraft crash we struggle to find any tiny positive elements to draw from the event. In this case, let’s be reminded of the benefit of careful periodic inspection of the exhaust system and associated heat exchanger: it may just prevent this kind of tragedy from happening to an airplane in which you fly.