Dealing with carbon monoxide in flight
I have written in 2019 about carbon monoxide detectors. This was following an aircraft accident involving a football star in the UK, with fatalities caused by lethal dose of carboxyhemoglobin within the blood vessels or carbon monoxide poisoning.
We all agree that the most important cause of lethal accidents in aviation will be caused with greater percentage in the line of LOCi (loss of control in flight), fuel exhaustion etc.
Flight safety, has to be taken globally and risk management is part of a modern solution to reaching this goal. Hence lies the issue of this article.
We all had to take a written exam for the type of licence we hold. Carbon monoxide questions were mandatory.
Theoretical vs real world
In Canada the AIM describes carbon monoxide as the result of an incomplete combustion. Perfect combustion is hypothetical, read here impossible. The perfect combustion would simply produce H2O and CO2. In the real world there will always be carbon monoxide produced when a combustion is underway. What level of CO is produced can certainly be minimized but never illuminated.
So let’s move on from the wonderful world of theory to the real world where we as pilots have to handle on a daily basis.
Here is the deal with carbon monoxide:
- It is deadly.
- The molecule will stick to hemoglobin 200 times more efficiently than the oxygen molecule.
- It is colourless, odourless (not all the time)
- Symptoms are lightheadedness, inability to focus, judgement impairment, dizziness, nausea. Those symptoms do set in early in the poisoning chain of events.
- The effects take hours to dissipate even when fresh air is applied.
- The effects are cumulative when sequenced doses are “applied”.
- Results of serious poisoning are loss of consciousness and death.
Like so many of us, when I acquired the PA-30, I mechanically purchased a cheap disposable carbon monoxide detector. This is the small plastic plate that seems to impersonate a scotch coaster. It is claimed that it will turn dark when CO joins the party in the cockpit.
Unbelievable luck
As luck would have it, just then, I got to listen to a most extraordinary podcast at AOPA “There I was”. (Select episode #13). An experienced pilot suffered total unconsciousness in flight due to CO. Eventually his aircraft ran out fuel and then started a glide by itself (there is nothing like a well trimmed stabilizer need I add) to land. I will call it landing not crashing, into a field. The field just happened to be in the flight path. When the pilot woke up he, not without trouble, managed to get out of the wreck.
To this day, I have never heard of such immense amount of luck.
A new detector, quick!
At that moment, it became urgent, to investigate a little deeper into CO detection. This is when I acquired an electronic CO detector that will sound the alarm when the CO particles become present. We are speaking here of 10 PPM (particles per million).
Unfortunately those disposable plastic detectors simply do not, repeat do not fess up to the urgency of the matter. They do make one feel good doing something about CO threat. That is all benefit they bring. By the time those claimed black spots show up (100 PPM), it will too late to react adequately.
If that was not enough, one has to envision that the demonstrated effects are measured at sea level. At altitude, with no oxygen, hypoxia sets in only to compound the story.
To recap, CO has to be detected extremely early in flight to illuminate its deadly chain.
Electronic detectors are the only way to go. Yes, they are more expensive than the $5 solution. Who cares? Sometimes risk management does require financial investment.
Every one including regulators are unconditional on the level of maintenance required for single engine exhaust shrouds heaters. We all know this. Here is my take on this paradigm with an improbable story.
It happened
A couple of days ago, I was completing a flight with my student who is about to undertake his private pilot flight test (check flight) in his C-172F. When I accepted to undertake this aspiring pilot training, I required that his 172 be equipped with an electronic CO detector. This was 2 years ago.
So this flight was on a cold late fall morning near Montreal (-12 degrees C) and the aircraft is in perfect shape as it should be. At altitude 4000 feet the OAT is -16 degrees C. The heather is full open. While undergoing manoeuvres that involved change of airspeed, the detector’s alarm sounded. The PPM readout was increasing past 40 PPM.
My student, applied proper technique by closing the heather and applying fresh air in the cockpit. The CO readout started to fall back. All the while, the symptoms started settling in: slight nausea, light dizziness and yes small headache.
No ambiguity here: we decided to come back to land. On the way in descent entering the downwind, my student established the circuit altitude at 2400 feet instead of the required 1400 feet! I let him carry on up to a point and then pointed to him his altitude. Some reaction time passed for him then to realize the condition. Here is one for judgement impairment, grand scale.
We broke out of the circuit to continue the descent, change of heading, change of speed and the alarm sounded off again, yet the heather was shout-off!
CO was coming in from the exhaust through the left door seal it was discovered on the ground.
The festive season is visual from here on this late December day. Take the time to tear off the plastic coaster if one is glued on the instrument panel. Then pamper yourself with an authentic CO detector. You owe it to yourself and your passengers under your care.