11 min read

On Monday, August 13, 2012, I came as close to dying in an airplane as I ever want to.

As pilots we study incident and accident reports in order to learn from the experiences of others. We put ourselves in their shoes and try to think what we would have done in a particular situation. Sometimes we think ourselves superior and that we would never make the mistake that an incident pilot made.

Accidents typically don’t stem from one cause or event. There is usually a series or chain of events that occur where if even one of the links were broken, disaster might have been averted. The accident pilot pushes on into deteriorating weather because s/he needs to be somewhere, a funny noise is ignored during run-up, etc. My case was no different. Looking back on it, I was lucky in spite of a series of events and decisions that contributed to my situation and could have ended very badly. Here is my story…

In February of 2012, I had taken a new job in in Winnipeg, Manitoba, after working as an executive at an energy utility in Vancouver for many years. My family was coming to join me that summer before the kids started their new school year. I was a private pilot at the time with about 1,000 hours, having received my private license in the spring of 2007. I had purchased my 1978 Cessna T210 in the summer of 2009, was instrument rated, flew regularly, and felt very comfortable with the machine. Sunday morning (the day before the incident) we closed up our cabin in north central Washington and flew back to my home airport (CYPK) just outside of Vancouver, BC.


Vancouver to Winnipeg means crossing some rough terrain.

The plan was for me to fly out to Winnipeg the following morning to meet the moving truck, which had departed with our furniture a few days earlier. It was surreal walking through the empty house my wife and I had designed and had rebuilt years earlier, and which our kids had grown up in. Nobody was too happy about the move that day but the rest of the family would be joining me later in the week after the furniture had been moved into the new place.

There was a lot of last-minute running around I had to do that Sunday, including fueling the plane for the five and a half hour trip the next day. We finally got everything done about 9 pm and took the kids for a late dinner at their favourite roadhouse close to our place. We then stopped in to say goodbye to some good friends and didn’t get home until after midnight. With no furniture left in the house, we settled in to sleep on a blow up air mattress and sleeping bags. Unfortunately, the mattress had a slow leak and I woke up several times that night having to put more air in. At about 6:30, I was up and on my way to the airport, still tired and bleary-eyed, only to find that there were a number of things I still had to deal with in the hangar, which I had agreed to lease out to someone.

The weather that morning was clear and calm but I had filed an IFR flight plan to Winnipeg at 17,000 feet. The trip was just over 1,000 NM and with daytime heating that time of year over the prairies it was usually a good idea to be high for smoother air. The plane was equipped with built-in oxygen and I had oxy-saver nasal cannulas, which I was used to using over the mountains and had never had any issues with. Unfortunately, my seasonal allergies were acting up and without realizing it I was mainly mouth breathing and not really benefiting from the oxygen through the cannula. About an hour and a half into the flight I had developed a mild headache and the coffee I had used to jump start my morning was making my bladder uncomfortable. I kept a big jug in the back seat for these situations but needed to move my seat back in order to reach it.

As I grabbed the seat lock under the seat and started to push back, the muscles in my shoulders started to cramp up, a wave of nausea washed over me, and I started to see sparkles in my field of vision. I stopped pushing the seat back and took a couple of deep breathes, the moment passed, and I sat quietly for a few minutes, breathing deeply. I was feeling better but after about 10 minutes or so the pressure in my bladder wasn’t going away so I again started pushing the seat back and my shoulders cramped up again, worse this time, and the sparkles in front of my eyes turned into narrowing tunnel vision as I started to gray out.

So there I was, alone at 17,000 feet on the edge of consciousness. I had the wherewithal to remember an acupressure point that my wife (a doctor of Chinese medicine) had shown me that’s used to revive people, so I pressed my forefinger sharply into the soft tissue just below the cartilage under my nose. It brought my field of vision back into focus and I dialed a 500 foot per minute descent into the autopilot and made a distress call to Vancouver Centre. I told them I thought I had hypoxia and needed to get lower. I opened the cabin vents and stuck my nasal cannula in my mouth with the flow turned up to high.

Earlier in the flight I had been cleared off the V300 airway GPS direct to Medicine Hat, Alberta. I was north east of Cranbrook, BC (pictured), and I requested the minimum safe altitude for the area. The center controller cleared me lower and asked me to intercept a radial off the Cranbrook VOR (YXC). As I looked at the flight plan waypoints on my G430 I couldn’t understand why he was giving me a radial for Cranbrook when I was already past Lethbridge, Alberta (or so I thought in the moment).

I didn’t realize how incapacitated I was at the time as I ploddingly compared my IFR low chart to the waypoints in my GPS and looked out the window. It finally dawned on me that I couldn’t possibly be east of Lethbridge, which was just east of the foothills of the Rockies, when there were still ice-covered mountain peaks below me. I finally got oriented and proceeded lower.

Pulse oximeter

Why would you need one of these if you’re wearing oxygen?

When I was about 10 miles west of Lethbridge, at about 9000 feet ASL, the controller asked if I wanted to land at Lethbridge (CYQL, field elevation 3049). I was feeling somewhat better but still shaky and didn’t feel capable of losing 6000 feet in 10 miles and landing safely, so I asked him to keep stepping me down as I proceeded on towards Medicine Hat (CYXH), 84 miles to the northeast. Although an uncontrolled airport, Medicine Hat had a flight service specialist (FSS) on site. Center handed me over to them as I approached and the FSS provided a traffic advisory. There was a student pilot and flight instructor doing circuits in the pattern on Runway 27 but winds were light and I advised I was going to land straight in on 04 (now 03 with the change in magnetic variation) and requested priority, which they gave me.

It certainly wasn’t the best landing of my career but I got the plane down without breaking anything and as I taxied off the active to the ramp, the flight service specialist directed me to a spot I could park. Just before I switched off the master I heard someone on the radio enquiring whether or not the “guy in the 210 had made in in okay?” The specialist advised I had just landed and the other pilot said that he thought I might have carbon monoxide poisoning because I wasn’t making any sense earlier on the radio.

As I walked away from the plane I called to some people standing outside the FBO door about 50 yards away, asking for help and sat down in the grass. Paramedics were called and I was transported to the local hospital about two miles from the airport to begin part two of my odyssey.

The ER wasn’t too busy that day and as it turned out the doc who saw me was also a pilot and a CAME (Canadian Aviation Medical Examiner). They did blood work on me and other tests to rule out a heart problem. I was 48 and in pretty good shape, running 8-10 km daily so I couldn’t see that as likely, but the blood work came back with a slightly abnormal enzyme level, which could be an indicator of a cardiac event. He wanted to keep me for observation and re-run the tests in four hours. Apparently if the enzyme level kept increasing that was bad.

It was a brutal afternoon in the ER. I listened as an elderly lady behind the curtain in the next bed coded and the staff worked frantically to revive her, sadly unsuccessfully. By the time they re-ran the tests and the results were back, I was spent. My blood was back in the normal range but the doc wanted to do a stress test on me prior to clearing me and the easiest way to do that was to admit me for the night and run the test in the morning.

I was moved to the cardiac ward upstairs, where I was poked and prodded on two-hour intervals through the night. The cardiologist was also a pilot who was doing his instrument training at the time, so we had lots to talk about while waiting for the report from my treadmill stress test. Meanwhile, my assistant in Winnipeg was at my new house relaying instructions from me over the phone to the movers where to unload the contents of the moving van. Unfortunately while the stress test report was normal as expected, I still needed to be cleared by the regional medical officer for Transport Canada in order to fly. Ultimately, I was grounded for 48 hours.


How did a simple flight end up here?

This left one final problem. I needed to get to Winnipeg with the plane. While I was in hospital a mechanic at the FBO had done an examination of the heat muff on the exhaust to ensure it was not leaking and it came back OK. So I hired my cardiologist’s CFI to fly the plane back with me to Winnipeg that afternoon. We got out ahead of some weather and filed for 7000 feet. I stayed on oxygen for the trip and landed uneventfully in Winnipeg that evening.

The epilogue to the story was that about two weeks later and before further flight, we pulled the cowl and did a thorough inspection of the engine exhaust system. We found a crack in the turbo inlet pipe on the backside, out of view and with exhaust soot in the area. So exhaust gases were escaping into the cowling and may have migrated past the firewall into the cabin, resulting in mild CO poisoning. My blood work did not show abnormal CO levels but did show signs that my heart had been stressed, which I understand is not inconsistent with mild CO exposure. Combined with the hypoxia, it could have been a lethal cocktail.

So what did I take away from my experience?

  • I definitely wanted to make it to Winnipeg that day—“get-there-itis.” The weather was good, but in hindsight I was over-tired and probably shouldn’t have flown.
  • I didn’t think of the impact my plugged nose had on my ability to utilize the onboard oxygen, which could have been a critical mistake.
  • I wasn’t aware of the hidden leak in my exhaust system.
  • All the planets had to align in a bad way for me to get in trouble, and as it turns out, most of them did. One break in the chain and I probably would have made it there without incident and been none the wiser. Or it could have gone the other way and I may not have made it at all.

Eight years later and with more experience under my belt, I am a little older, perhaps a little wiser and (I think) a safer pilot. I fly with a CO detector in the cockpit. I pay closer attention to my body and follow the IMSAFE checklist before flight. I also use a facemask with rebreather for oxygen when flying unpressurized over 10,000 feet. And I continue to read incident reports in order to learn from other’s experiences.

I hope that relating my story may help keep someone else from making some of the same mistakes I did…

Scott Thomson
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11 replies
  1. Greg Laudick
    Greg Laudick says:

    First of all, so glad to hear you made it down safely and still flying! Thank you for sharing your story. I learned to fly in 1982, but quit after 12 years to raise a family. Well, they’re all grown now and I’m retired as of August 2020. Guess what I decided to do to fill my time…yep…I got re-certified and my 3rd Class Medical. I flew Cessna’s as well, so your story hits close to home, and the sharing of experience has me taking a whole different approach to flying than 40 years ago. Just purchased part interest in a brand new Cirrus SR20. What a difference that is. But I’m having a ball and learning every day, and your story added to that learning. Safe flying to you and Mrs.!

  2. Greg Curtis
    Greg Curtis says:

    Thanks for your story, Scott. It is very often we read a successful end to either a hypoxic or CO poisoning incidents. One must always expect a very thorough examination following your type of situation particularly when your doctors are fliers also. Your story will be good reading for our students in our Human Factors class in the Aviation Program at University of Maine at Augusta.

  3. Cary Alburn
    Cary Alburn says:

    Interesting situation—and it’s nice to read of a successful outcome. When I think of all the times I flew in my earlier aviation life at very high altitudes (following the FAA dictates on oxygen use, of course), I wonder why something similar didn’t happen to me. I’ve flown in the flight levels in a T210 and a TR182 many times, using cannulas below 18,000’ and a mask above 18,000’. Now my P172D doesn’t have the capability of flight levels, but it can cruise at 14,000’, and I use a cannula.

    The question is, do the FAA dictates have any relationship to real world oxygen needs? And I submit that they don’t. They are much too lax.

    Several years ago, I bought a quality pulse/oximeter, and I immediately discovered that my tolerance for the higher altitudes requires more oxygen to maintain a reasonable O2 percentage in my blood, which I understand to be 92%. Perhaps it’s because I’ve aged, but I honestly don’t know if my higher personal oxygen requirement existed a long time before I started regularly using the pulse/oximeter, even when I was much younger. But now if I ever fly above 10,000’ (which happens relatively frequently on cross countries because of where I live in Colorado), I go on oxygen. I have to consciously force myself to breathe through my nose, because habitually I’m a mouth breather. But by regularly checking my O2 percentage, consciously breathing through my nose, and turning up the O2 flow meter for roughly 2,000’ above my flight altitude, I can maintain a safe percentage.

    So I encourage any pilot who regularly flies above 10,000’ to invest in a pulse/oximeter, and to use supplemental oxygen if it shows less than 92%. Oxygen is relatively cheap—much cheaper than suffering a hypoxic incident, which often results in death.

    • Scott Thomson
      Scott Thomson says:

      Cary, I have found that I feel okay down to about 90% when flying and with a cannula I am usually in the low 90s above 10,000 using the recommended flow meter calibration but if I use a full mask with rebreather I am at 98% plus. Interestingly my normal oxygen saturation at sea level is 96-97%.
      I am not a medical person but was told that CO poisoning can trick a pulse oximeter into thinking you are ok because it sees the CO as O2. I don’t know if that is correct and it is likely that I had mild CO poisoning combined with hypoxia. A CO detector in the cockpit can be a life saver.
      I have observed hypoxic pilots that are talking gibberish one minute and after descending a couple of thousand feet are completely coherent. That was the indicator of CO in my situation because I was still feeling physically challenged after landing. It passed as the day progressed.

      • Cary Alburn
        Cary Alburn says:

        Scott, I’ve seen the same information, that a slow CO leak can fool a pulse/oximeter. I also have a pricey panel mounted CO detector in my airplane—don’t trust the little spot cards that some use to do anything useful.

  4. Rick Junkin
    Rick Junkin says:

    Thanks for sharing your Story Scott. It vividly stresses the importance of flying with a CO detector and regular pulse-ox monitoring when flying in the O2-required altitudes. Your story and you follow-on mitigation actions serve as a great example and will save lives.

  5. Michael Frank, MD JD
    Michael Frank, MD JD says:

    Great story, and lessons learned appreciated, but the conclusion drawn about inability to utilize nasal cannula oxygen when mouth breathing is incorrect, & putting the nasal cannula in the mouth was unnecessary. Oxygen delivery was not the problem. It was the carbon monoxide. Oxygen delivery by a properly positioned nasal cannula will entrain oxygen into the airways quite nicely when mouth breathing, even when the nasal passages are congested or blocked. The details of the incident and later discovery of the exhaust leak make it pretty clear that the problem was CO toxicity and not ineffective oxygen delivery. Normally oxygen binds to hemoglobin passing through the lungs, forming oxyhemoglobin, which is then carried to the tissues (including the brain) where the oxygen is then released. Carbon monoxide binds to hemoglobin with much greater affinity than oxygen, so there is less capacity to bind oxygen and carry it to the tissues. When the amount of oxygen released to the brain tissues drops, tissue hypoxia occurs with resulting confusion progressing on to unconsciousness. Most pulse oximeters are unable to differentiate oxyhemoglobin from carboxyhemoglobin, so CO poisoning usually goes undetected with these devices. As the author suggests, a cabin CO detector is the way to go. Best to use one that has a sound or light alert, rather than the color change cards which may or may not be promptly noticed. Note that a normal or near normal blood level of carboxyhemoglobin does not rule out CO toxicity, since the levels will begin decreasing once the exposure is eliminated, but the toxicity symptoms may persist for much longer, just as occurred in the episode described by the author. It is likely that the interval between the time he landed, and the time the blood sample was taken in the hospital was more than sufficient to drop the CO levels. The bottom line is that all the facts point to this as an episode of CO poisoning from an exhaust leak, and not hypoxia from failed oxygen delivery.

    STEVEN YUCHT says:

    I suspect CO poisoning had little to do with your situation. As an Emergency Medicine physician, AME and pilot I can tell you confidently if CO was an issue they would have found an abnormal CO level at the hospital and you wouldn’t have recovered your cognitive function at a lower altitude. One could argue that you were at the borderline of CO and threw on some hypoxia to push you over the edge but it really was the hypoxia that resulted in your problem. At low levels CO poisoning will generally cause you to have a headache and become tired. The real risk for CO is as levels increase you lose consciousness. If you believe that CO is a possibility get on O2, slow below window opening speed, make sure that all vents are off, and expedite a precautionary landing. Overall I’d say you handled this well. You declared the situation, got lower and landed the plane without incident. Cant ask for much better.


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