Miracle Over Minnesota… Survival After Carbon Monoxide Poisoning

by Dan Bass
Published in Midwest Flyer – October/November 2020 issue
@October 2020. All rights reserved!

In February 2017, I needed to visit a customer in Thunder Bay, Ontario. By car, it’s over a 7-hour drive from Winona, Minnesota, where I live. But my Mooney would allow me to easily make the trip there and back in one day. With the exception of being cold, the weather looked great for a trip up north.

I woke up early for a planned 6:30 a.m. departure. The day before I filed my eAPIS (electronic Advance Passenger Information System) flight manifests online as required of U.S. Customs & Border Protection (CBP). I also notified (as required) the Canada Border Services Agency (CBSA) via 1-800-CAN-PASS that my estimated time of arrival (ETA) would be 9:00 a.m. local time. I planned for a 2.5-hour flight to Thunder Bay.

I plugged in my engine and cockpit heaters the night before, so once I got the plane out of the hangar, I climbed into a warm cockpit, but that didn’t last for long. On the taxi out it was clear that I would need to run the cabin heat and defrost on full blast. Other than the bitter cold, it was a beautiful day to fly. A high-pressure system sat right over Minnesota and promised clear skies for the region for the next two days. Though I departed Winona about 15 minutes behind schedule, the CBSA provides an arrival window plus or minus 30 minutes from one’s scheduled ETA, so I wasn’t too concerned. I picked up my IFR clearance on the climb and settled in for a nice flight.

As I enjoyed the beautiful sunrise to the east, I felt something irritate my eye. I started rubbing my eye and wondered, “Could this be carbon monoxide (CO)?” I turned the heat off and opened the fresh air vent. The cabin temperature quickly became unbearably cold and I realized that eye irritation isn’t a symptom of carbon monoxide poisoning. I switched the fresh air off and turned the heat back on. My eye rubbing paid off and I felt good again. That was the last time I thought about carbon monoxide that day.

The flight to Thunder Bay was normal with the exception of two things: 1) I was cruising at 10,000 feet MSL and it was common practice for me to check my SpO2 saturation levels. (SpO2, also known as oxygen saturation, is a measure of the amount of oxygen-carrying hemoglobin in the blood, relative to the amount of hemoglobin not carrying oxygen.)

I don’t recall the exact number, but I do remember that my SpO2 level was several points higher than normal at that altitude, and thought to myself, things were going great! But the other unusual observation was that all my side windows were frosted over. This was normal if I had four people onboard when it was this cold outside. But I have never experienced problems before with the defroster not doing the job with just me in the plane. I figured that on that day, it must just be extra cold or maybe the humidity was higher than normal. I didn’t give it any more thought, yet both of these things were signs of what was really happening.

During the last 10 minutes of the flight, I started to get a slight headache. I immediately thought of the coffee I had skipped earlier that morning. I start everyday with coffee and assumed this was the start of the inevitable lack of caffeine headache, but it wasn’t.   

Once on the ground in Thunder Bay, I called Canada Customs using my cell phone while I was still in the airplane. The agent asked me what time I landed, and I responded, “Just now, at 9:15.” My answer seemed to confuse him for a minute and after some contemplating, he instructed me to write down a clearance number for my records and stated that I was all set. This was my first time flying to Canada and I was pleased to clear customs so easily. But I was still concerned that I may have missed something.

Again, it was bitterly cold that day, so I quickly secured the airplane and sprinted across the ramp into the warm FBO. As I made arrangements with the lineman for fuel, I noticed the wall clock displaying 10:15 a.m. The lineman confirmed that Thunder Bay was on Eastern Standard Time, not Central. I now understood the confusion with the customs agent on the phone. I had arrived over an hour after my scheduled ETA, well outside my plus or minus 30-minute window. It also just occurred to me that I would be late for my meeting as well. During all of this, I had a feeling of “butterflies” that was very unusual. Given the situation, I passed this feeling off as anxiety.

Throughout the morning, my headache came and went with varying degrees of severity. At lunch I had a few cups of coffee and the caffeine seemed to remedy the situation. By 3:30 p.m., my headaches were gone, and I was looking forward to the flight home.

I departed Thunder Bay for Duluth, Minnesota (KDLH) to clear U.S. Customs. I remember it being an incredible flight. Smooth, clear skies with great views of Lake Superior to my east, and a nice sunset to my west. I felt great for the entire 1 hour 20-minute flight.

The customs agent met me at my airplane on the ramp at Duluth. After I climbed out of the airplane and stood up on the wing, I immediately got a sharp headache. The agent and I quickly moved inside out of the cold to finish the paperwork. Once completed, I used the restroom and called my wife, Deanna, to let her know I would be home in a little over an hour. My headache persisted.

Up until this point, with the exception of the last 10 minutes of my flight to Thunder Bay, I experienced all of my symptoms while I was not inside the airplane. Up to now, I was able to rationalize my symptoms being caused by a lack of caffeine and some anxiety. But with this headache, my thoughts turned to our 4-year-old daughter, “Lilla.” For the preceding week, Lilla was not feeling well. Being only 4, she wasn’t able to articulate exactly how she was feeling, but we knew she was ill. I now rationalized the way I felt the entire day, thinking I was catching whatever Lilla had.

After finishing up with customs in the FBO, I quickly ran to and boarded the airplane. The outside air temp was around 0 degrees Fahrenheit and I wanted to get the airplane started before the engine had a chance to get too cold. Once it started, I got to work on filing my IFR flight plan to Winona using my iPad. I knew it would take several minutes for the flight plan to make its way into the system, so I used this time to prepare the cockpit for the flight. As the airplane idled on the ramp with the heater on full blast, I placed my flashlight, hat and gloves on the passenger seat within easy reach. I donned my headlamp (I always wear one during night ops) and strapped on my kneeboard. After a few minutes, a notification on the iPad acknowledged that my flight plan had been received by air traffic control (ATC), so I contacted ground for my clearance. It was approximately 10-15 minutes from engine start to my taxi clearance.

While taxiing out to Rwy 27, I still had the headache that came on when I exited the airplane. I then experienced another episode of “butterflies” — this time more intense than the morning episode. It only lasted for 15 seconds and then just like that, I felt better with no butterflies or headache. As I got to the runup area, I remember wondering what was going on, but I continued with my runup. At this point I became hyper-focused and ran through my checklist over and over. It was almost as if I was reluctant to takeoff. After several minutes of re-running my checklist, the tower contacted me and asked if I was ready to go. This snapped me out of my checklist loop and I responded with “we’re just about ready to go.” About 30 seconds later, the tower responded with my takeoff clearance, “Mooney 49V, turn left heading 240, Rwy 27, cleared for takeoff.”

In hindsight, I wasn’t playing with a full deck at this point, but I had no idea at the time. I taxied onto Rwy 27 and advanced the throttle. Just after liftoff while reaching to raise the gear, I had another intense episode of butterflies. Again, this was very short, lasting no more than 10-15 seconds. As quickly as it came, it went away, and I didn’t have any idea what was happening to me. I started the left turn, turned my heading bug to 240 degrees, and engaged the autopilot. This autopilot only had altitude hold, so I manually trimmed it for a 105 kt climb. This is when things started to happen quickly. The next few minutes started to blend together in my memory. I had a traffic call-out from the tower and then a handoff to departure. My responses to ATC were becoming difficult and I recall slurring some of my words. At this point I realized something was terribly wrong. I remember hovering my left thumb over the autopilot disconnect button on the yoke, but I was reluctant to change anything. I wanted to tell ATC I needed to land, but I didn’t. I kept going through the motions, not in control of my actions. I entered my “direct to” for Winona (KONA) into my Garmin GPS nav com, and the very next thing I remember is waking up.

I figured I had dozed off. I keyed the mic and tried to contact ATC to let them know I was alright and needed to land. While I was trying to contact ATC, I marveled at how clear my windscreen had become. I was rather impressed… I have never seen it so clear. I reached my hand forward to touch the window, but it wasn’t there. I started to take in my surroundings and realized I wasn’t in the air anymore. I had crash-landed in a field.

I was very impaired at this time; my waking up was rather slow and dream-like. The realization that I had crashed didn’t hit me right away. As I slowly realized what was going on, I tried to get out of my seat, but I couldn’t move my legs. I assumed I was paralyzed, but that thought didn’t bother me; a testament to my level of impairment.

I then noticed a search light from a road vehicle about 1 mile off my right wing. Despite my not fully understanding what was going on, I somehow knew that the light was looking for me. I tried to turn on any external aircraft lights to no avail. I tried my interior dome light, but I didn’t have the strength in my fingers to rotate the switch in the right direction. I then went for my flashlight, but it was nowhere to be found, so I reached for the headlamp I had been wearing and it too was gone. I had nothing in my reach that could help me signal for help. A helicopter had also flown overheard a few times in what appeared to be a search pattern. I was confident people were trying to get to me.

The searchlight and helicopter had both disappeared over the horizon and my thoughts turned back to my legs. I remember looking down at them and trying my darndest to move them with no results. I then thought about my toes. I was able to wiggle them, so I knew I wasn’t paralyzed. I struggled a bit more and realized that my feet were pinned under the rudder pedals. My right foot came out fairly easily, but my left foot was more stubborn, and it took several minutes to free it. Once moving, I climbed out onto the wing with the thought that I needed to get to where I saw that searchlight.

Deanna had sent along a pair of Carhartt bib overalls to protect me from the cold in the event I had a forced landing. I retrieved them from the luggage compartment and in the process of trying to put them on, I fell back onto the wing and after a few more attempts, I gave up. So, I tossed them aside and went back into the airplane to collect my Carhartt jacket, hat, and gloves.

Before the flight, if you recall, I had my hat and gloves located on the passenger seat, next to my flashlight, and just like my flashlight, my hat and gloves were now missing. In my search, I found my cell phone which had an error message displayed, so I tossed it aside, and I found my iPad. Garmin Pilot was still running, and I was curious as to where I ended up. I knew I was headed south, and I wondered if I made it as far as Iowa. Once I determined that I was still in Minnesota, I set my iPad to the side, not realizing it could be used as a signaling device. Another example of my impairment.

I had been exposed to the bitter cold long enough that I lost all dexterity in my fingers and was unable to zip up my coat. So, with an unzipped coat, no hat or gloves, I set out toward the area of the searchlight, but after taking only a few steps, I fell to the ground. I got back up and took a few more steps and fell, again. I was very weak and had poor motor skills, but I was determined. I walked, stumbled, and crawled across a snowy, frozen, plowed field. About 100 yards from the airplane, I was spent. I rolled over on my back and started to feel warm and comfortable. The helicopter was heading back my way, this time flying directly over the airplane and me. I yelled and waived my arms to no avail… It flew on.

I had no intention of getting up. I thought to myself, “If someone finds me, great. If not, no big deal… I don’t really care.” I settled in and enjoyed the view of the brilliant stars on this moonless night.

Three years previous, almost to the day, Deanna went into labor with our second daughter. We knew it was a girl but hadn’t decided on her name yet. One of the names we were considering was “Maia,” after a star in the Pleiades star cluster, aka Seven Sisters. At midnight, I was loading Deanna into my truck to bring her to the hospital. She paused and said, “we don’t have a name for this girl yet.” I looked up and Pleiades was directly overhead; we had our name.

Now I was lying on my back near a broken airplane and directly overhead, was Pleiades. Up until this point, I hadn’t thought about who I was or if I had a family. As my life unfolded in my mind, it gave me a reason to not give up, so I sat up and surveyed my surroundings. Looking back at the plane, I noticed a security light near some outbuildings on the other side of a wooded area beyond the crash site. I estimated this was the closest thing to me and my best shot at finding help.

I made my way back to the airplane, much easier than before. I was gaining strength and coordination by the minute. Cognitively, I was also sharper. I started to understand the gravity of what had happened. As I walked by the rear of the airplane, I patted the stabilizer and said, “Thank you!”

When I reached the edge of the wooded area, I was faced with thick undergrowth to walk through. I remember thinking, “If I was healthy, I would walk around this,” but it stood directly in the way of where I wanted to go, so I trudged forward. I found myself tangled in this brush, unable to move forward.  After some time, I realized that I was pressed against a barbwire fence, then dropped to the ground and crawled beneath it.

Once in the woods, I found the trees to be a blessing. I was able to use them to steady myself and stay mostly upright. But the woods also challenged me with deeper snow. The field I had been navigating was windswept with very little accumulation. When I would fall, I remember crawling in the snow with my bare hands that now had no feeling and felt heavy as if they were concrete blocks. I was very upset at the idea that I may survive but lose my hands.

As I approached the service light, I could just see these two outbuildings. When I skirted up along the side of one of them to peer around it, a house came into view. The windows had a beautiful blue flicker that only a television emits. I somehow made my way the last 100 feet across an icy gravel driveway without falling even once. Lucky for me, this was the home of Cynthia and Chuck Crabtree. Cynthia was home alone that evening, but thankfully a bloodied, seemingly intoxicated man pounding on her back window didn’t scare her into hiding. She brought me in out of the cold and alerted authorities; a sheriff deputy showed up just minutes later. Shortly after that the paramedics were transporting me in a medivac helicopter that had been flying overhead earlier.

Once I reached the hospital, it was four days until I was able to stand up again. I used a walker for two weeks and then needed a cane for another month. It was 16 weeks before I could go without a back brace. The worst of my injuries were three broken vertebra in my back, the loss of two teeth, a broken upper jaw, a large facial laceration, and all of my fingers experienced frostbite. The neat part of my recovery was that I was released from the hospital five days after the accident on our daughter, Maia’s, third birthday.

So, what happened?

Lessons Learned

I learned later that the aircraft had a crack in the muffler underneath the heat shroud. While running the cabin heat, carbon monoxide rich exhaust was being pumped into the cabin. The cause of the crack is unknown. It wasn’t there 89 hours before when we pressure tested the exhaust at annual. On a flight the day before the accident, I experienced a backfire at startup. Backfires were rare in this airplane. I have only experienced two or three over the course of owning this airplane. It’s possible that the backfire caused the crack or at least exacerbated it. During all three flights that day, I was being slowly poisoned by carbon monoxide.

Carbon monoxide is an invisible, odorless, tasteless, colorless gas that is created by the incomplete burning of fossil fuels. When it is inhaled, it combines with the hemoglobin in the same space meant to carry an oxygen molecule, thus rendering the oxygen carrying capability of that hemoglobin useless. The CO bond is over 200 times stronger than the oxygen, so if CO is present, it’s very effective at poisoning you. The half-life of CO in the human body is around four to five hours. So, when I started my second flight from Thunder Bay to Duluth in the afternoon, there would still be some CO in my blood from the morning flight, creating the perfect storm, building on the CO from the previous flights.

Because of the build up from the previous two flights and the prolonged ground run in Duluth, it only took about four and a half minutes from takeoff until I lost consciousness. I was climbing through 4,500 feet when the lights went out. From there the airplane continued to climb on its own with the autopilot keeping the wings level while tracking the heading bug. Fortunately, the mixture was still full rich from takeoff, that only allowed the airplane to climb to 12,500 feet. If the mixture were leaned at all, I would have climbed higher and went further. Being that I was already oxygen deprived, I’m sure that would have been fatal.

I missed a lot of excitement over the next two hours I was asleep. The flight brought me right over the Class B airspace at Minneapolis/St. Paul International Airport (KMSP). I was intercepted by two F-16s that were scrambled from Madison, Wisconsin (KMSN) that apparently checked me out, and the pilots determined that I was not a threat. Shortly after my impromptu formation flight, the selected fuel tank ran dry and I started my descent. Somehow the airplane “landed” in a very small, 800 ft. field with power lines on one end and trees on the other. It was around 30 minutes after impact that I woke up. Luckily the windshield broke open exposing me to fresh air that woke me up and gave life back to my otherwise lifeless body.

Some CO Lessons Learned

I didn’t have a CO monitor onboard my aircraft. I thought I would be able to recognize the symptoms and take action. By the time I was experiencing symptoms, my cognitive abilities were already being compromised. I had symptoms that would come and go, which were easy to rationalize. I always assumed I would “know,” and that assumption nearly killed me.

The only reliable way to detect and prevent exposure to CO is with a digital “carbon monoxide detector.” I like the ones that have a parts per million (ppm) display and include visual and audible alarms. These detectors can be used to not only prevent a catastrophe, but they are accurate enough to detect very small exhaust leaks well before they are dangerous. If I had owned one, I would have noticed a problem weeks or months before this accident. Detectors give immediate feedback to the health of an exhaust system.

I discourage the use of the card-type detectors, as well as the home electronic detectors. The cards have a short useful life and are often unreliable. The home detectors might prevent a catastrophe, but they lack the sensitivity that is useful for troubleshooting and catching issues early.

It is also important to note that only half of all CO accidents are attributed to defects in the heating system.

CO is a problem year around and the statistics don’t favor a season or geographic region. Nearly all of GA is susceptible to CO.

It’s also a good practice to use a “pulse oximeter” to monitor your oxygen saturation. I use one on every flight. One would assume that CO poisoning would show up with a lower oxygen saturation reading, but it’s the opposite. The pulse oximeter uses the color of blood to determine oxygen saturation. When CO is present in the blood, the pulse oximeter will actually display a higher saturation reading. This is why I had a higher-than-normal reading on my first flight.

Non-CO Lessons Learned

Get shoulder harnesses! My airplane had harnesses, but many legacy airplanes do not have anything more than a lap belt. The diagonal bruise I had across my chest proved it saved my life.

Keep all needed survival gear on your person or fixed to a part of the airframe within reach. I now fly with a flight vest and keep items such as my cell phone, personal locator beacon, portable strobe, flashlight, signal whistle, and signal mirror on me. I might look like I’m ready for combat, but the equipment would have come in handy that night. My handheld VHF radio is always charged and positioned near my left leg. Before this accident, I thought pilots carried handhelds onboard in the event of com radio failure. But in reality, their real value is to be able to communicate with someone from the ground following an accident.

Simple Precautions Can Save Your Life

Simple precautions can help prevent carbon monoxide poisoning, according to the Mayo Clinic in Rochester, Minnesota. In addition to having a carbon monoxide detector in your aircraft, it is recommended to have one in your boat and motorhome. Also install detectors in the hallway near each sleeping area of your home.

While it is recommended that pilots ship their detectors to the factory to have their batteries replaced and the detector checked for accuracy at recommended time intervals, the batteries of fixed detectors in your home or office should be checked every time you check your smoke detector batteries – at least twice a year. If the alarm sounds, land immediately or leave your home and call 911 or the fire department.

Don’t fly if you feel ill. All pilots are required by the FAA to ground themselves should they feel medically unfit to fly for any reason, and it’s just good common sense. Just because we need or wish to be somewhere at a given time, or we want to get home, is not a sufficient enough reason to fly.

Which Detector To Buy?

There are hundreds of CO detectors on the market. However, most of them are not well suited for aviation. They may not alert you until CO concentrations reach over 100 ppm, or they may not have an alarm that is audible in a noisy cockpit.

Detectors range in price between $129.00 to $170.00, depending on desired features and personal preference.

The CO detector I own and recommend is the Sensorcon, and I have worked a deal with the manufacturer that can save pilots 20% by going to their website sensorcon.com and using the code Aircraft2020.

Sporty’s Pilot Shop has flown with and recommends the following three detectors: Tocsin 3 CO Cockpit Monitor, ForeFlight Sentry ADS-B Receiver, and Aithre Shield Carbon Monoxide Detector.

Tocsin 3. This is Sporty’s Pilot Shop’s overall top pick in carbon monoxide cockpit monitors, which sells for $169.95 (Catalog 7761A). It features three alert modes – a 90 db audio alarm, flashing red lights, and vibration – so pilots will notice it in the cockpit. The built-in screen gives pilots a real time indication of CO ppm, but it’s still small enough to mount almost anywhere. You can use the sturdy clip to keep it attached to a seat belt or mount it to the panel so it’s in view. The default low alarm is set at 35 ppm and the high alarm is set at 100 ppm. The Tocsin 3 also has a TWA setting for 8 hours, but this is less important unless you’re troubleshooting a persistent problem.

ForeFlight Sentry. This all-in-one ADS-B receiver does more than just receive weather and traffic. It also features a built-in CO detector that alerts pilots via a loud audio alarm, a flashing red light, and a pop-up alert in the ForeFlight app. This makes Sentry a solid safety tool, and it can be mounted out of the way if necessary.  The ForeFlight Sentry retails for $499.00 (Catalog 6891A).

Aithre. This tiny detector takes a different approach. It is a standalone CO detector and alert device, but it also connects to a free iOS app to offer detailed monitoring. You can track ppm levels with a 15-minute history or get pop-up messages and Siri voice alerts. It uses a rechargeable battery and includes a handy mounting clip. The Aithre retails for $130.00 (Catalog 6184A).

For additional information, see “Carbon Monoxide Detectors” on the Sporty’s Pilot Shop “Safety & Survival” page at Sportys.com.

EDITOR’S NOTE: Dan Bass lives in Winona, Minnesota, with his wife, Deanna, and two children. He owns and operates Mec-Pro Mfg, a custom equipment manufacturing company founded by his father in 1975, who was also a pilot and aircraft owner. Dan soloed on his 16th birthday and received his Private Pilot Certificate on his 17th birthday. He is currently a Certified Flight Instructor with 2500 hours. After his accident, Dan replaced his Mooney M20C Ranger with a Mooney M20K 231. He and also owns an Ercoupe.