Silent and deadly

We decided to start with a short cross-country and were about five miles from the airport when I noticed a warning light. I mentioned it to the instructor, who immediately recognized it and acted to prevent something that could affect us both.

The warning light was labeled Carbon Monoxide (CO). This is something that is covered in the knowledge tests and pilot test prep, but rarely comes up in real life, at least not as dramatic as looking at a bright light telling you there is a tasteless, odorless gas in the cockpit that can kill you. 

The instructor commended me for seeing the light and started to open the vents, shut off the cabin heat, and turn on the cabin air. It was evident he was doing the right things, including waiting a few seconds after the corrective actions to ensure the light was not just being finicky or was broken. The CO light had activated before, but only for a few seconds. In all, the entire process from identifying the light to deciding to turn around back to the airport took one minute. The reason I am so sure about the time is that I had a camera in the cabin that recorded the entire incident. We turned back to the airport, and I predicted the light would go out after we landed, which it did.

After we landed my instructor found an issue with the exhaust line, which he reported and helped to prevent any further incidents. It seems that the Robinson R22 doors were not used much until recently because of the warmer weather, which is why it hadn’t been a problem on recent flights.

Carbon monoxide is produced as a byproduct of exhaust emissions from engines, and helicopter engines are no different. The NTSB recommended requiring carbon monoxide detectors in airplanes and in helicopters in 2021 after a review of accident reports identified 31 accidents attributed to carbon monoxide between 1982 and 2020 resulting in more than 40 deaths. The idea that such a little molecule could cause havoc made me realize just how important it was to understand and combat this type of danger. 

The lessons that I learned from this incident are three-fold. First, always check the warning lights and gauges. It is drummed into your head during each flight to do a landing or maneuver check, but it should be done as part of your normal scanning. I just happened to be looking at the warning lights when the carbon monoxide warning light came on. Call it luck, but I hope it was just part of the routine scan. Second, practice a carbon monoxide warning emergency so that you can do the corrective measures by heart. Third, and final, this incident raised my alertness to the carbon monoxide problem and to not treat it like something that one can just ignore until it goes away. The light is there for a reason. I am hoping that I never have to take corrective action again but knowing what to do is the first step in knowing when to do it. If the light is lit, you must commit.

Chris Greco is a private pilot with more than 200 flying hours, with over 40 hours in the Robinson R22 helicopter. He has been flying periodically since 1972.