NTSB Asks FAA To Require CO Detectors For GA Aircraft


The National Transportation Safety Board (NTSB) released a safety recommendation report on Thursday calling for the FAA to require carbon monoxide (CO) detectors in general aviation aircraft. In addition, the report specifies that the agency should require CO detectors that comply “with an aviation-specific minimum performance standard with active aural or visual alerting.” The recommendation applies to all enclosed-cabin aircraft with reciprocating engines.

“The FAA’s current recommended exhaust system inspections and replacement schedules have not prevented fatal aircraft accidents due to CO poisoning,” the NTSB said in its report (PDF). “The NTSB is concerned about the continued hazards resulting from CO poisoning because the FAA does not require CO detectors on enclosed-cabin aircraft. The NTSB concludes that use of a functional CO detector to alert a pilot through visual and auditory means to the presence of CO before the pilot’s judgment is impaired is necessary to the continued safe operation of the aircraft.”

The NTSB says it has identified 31 accidents attributed to CO poisoning between 1982 and 2020, 23 of which were fatal. Of those, it found that only one of the accident aircraft was equipped with any kind of CO detector. The Board first asked the FAA to require CO detectors in GA aircraft with enclosed cabins and forward-mounted engines in 2004.

Kate O'Connor
Kate O’Connor works as AVweb's Editor-in-Chief. She is a private pilot, certificated aircraft dispatcher, and graduate of Embry-Riddle Aeronautical University.

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  1. I agree with the NTSB that the use of a CO monitor is a very good Idea. I currently fly with a CO Experts detector on all flights. I would hate to see the FAA mandate the monitors that would have to be certified, mounted in the aircraft, and cost far too much.

    • Totally agree. There’s nothing to prevent someone from putting a CO detector in his aircraft now. But mandating a (likely) certified one is not the best way to go.
      NTSB refers to 23 fatal accidents where CO was a factor in THIRTY-NINE years. This is not a pressing issue.

  2. In general I am against government intervention but this may be a good idea.

    I agree that if they come up with some new certification standard we are looking at $800 CO monitors that Home Depot sells for $30. Like the difference between a Garmin In Reach and a 406 ELT.

    GA exhausts are built like crap, and it does not take much CO to put a hurt on the human organism.

    • And don’t forget, CO detectors (no matter what kind) only have a limited lifespan (5-10 years, typically) before they have to be replaced. So it’s not even like ADS-B, because at least once you buy that, you don’t have to regularly replace it.

  3. Although some kind of CO detector would be a good idea, the “aviation specific” detector that meets a FAA standard would be pricey for most small planes. If we followed every “safety” item the NTSB proposed, GA would be no longer and the industry, what would be left of it, would not be aviation. I wonder how many of the CO related accidents pointed out by the NTSB were pt91 vs pt135.

  4. I bought a ‘Toxin Sensors – Carbon Monoxide Detector’ about four months ago and recommend it highly. My jacket has a chest pocket that the CO detector lives in all the time. When I’m working around the farm the tractors, trucks and equipment are regularly setting it off. Four short beeps and flashes is telling you that the CO is 25 to 100 parts per million (PPM). If it’s one long beep it’s over 100 ppm. Two long beeps 200 ppm and so on. It’s sensors is good for ten years and battery is about five years if it is turned on all the time. $60 each ten years is fairly cheap insurance. When flying around the CO Detector is within a foot of my nose. So far it hasn’t gone off while flying but I trust it will if the CO is over 25 ppm.

  5. Are pulse-oximeters a good alternative to CO detectors? I know they don’t alert the presence of CO but could perhaps be a decent cheap early warning system. Does anyone know if that is viable?

    • Most pulse oximeters (which otherwise work well) don’t differentiate between oxygenated hemoglobin and carboxyhemoglobin. Some studies actually show increased SP02 levels as the inhaled CO becomes moderate to excessive. Some type of ambient CO monitoring isn’t a bad idea. I’m hoping that a good quality, portable over the counter device will keep the boys happy.

    • CO and O2 sensors are a must. Even if the presence of CO and the lack or O2 doesn’t kill, it is damaging to the body to be infiltrated with CO, likewise hard on the organs every time they are starved of O2. The O2 sensor might also be an early warning device if having more serious troubles such as blockage or COPD.

      The sad part is that we need the government to tell us this.

      Many small aircraft are flying around without fire extinguishers and or first aid kits……and the beat goes on…

  6. After hearing about an almost accident in a brand new model Cessna (from when I used to work for Cessna), I installed a solid state CO detector in my Glasair. (You need to check them every year – else you don’t know if the sensor is still reacting to CO.)

    In the case of the almost accident, the only thing that saved four employees was that the flying pilot was a new pilot (or possible still a Student Pilot) who became Airsick easily. As a result, he had the overhead wing root vent pulled all the way out, pointing directly at him, even tho it was freezing cold outside. The 3 paxes all fell sound asleep.

    Maintenance called the next day to show everyone a large gray streak running from an exhaust slip joint into the cabin heat shroud. On a brand new plane, with only ferry time from KS to NY on it.

    Ever since that visual, I have a Rule: At least one vent stays open in flight, no matter how cold it is inside.

  7. Not wearing a CO detector, which Aviation Consumer reviewed and recommended, I believe, a few years ago, is basically engaging in another “stupid pilot trick”. Ya know people carp about the FAA making requirements akin to complaining about their mother’s reminding them to put on their galoshes when it’s raining. “No one is going to tell me what to do!” and in the next breath complain that they got a cold, or in the case of aviation, cracked up their plane, and if they were lucky, ended up in the hospital with repairable wounds. Sheesh!

    • These were just the reported accidents related to CO. How many pilots crashed during that period that weren’t tested for CO? How many pilots got sick during a flight, didn’t crash, and didn’t report the inflight illness?

  8. I have to agree with another poster,23 fatal accidents in 38 years, while unfortunate, is hardly a reason to go crazy. Are CO monitors a good idea, sure. Are they readily available inexpensivly, sure, the RV industry has been using them for years. Problem is, if the FAA jumps on the bandwagon,we’re going to find a STC’d version for upwards of 1000 because it says “aircraft “ on it.

    • Yes so true. And if I was the manufacturer of said detector I would price it like that just to cover added liability.
      Certified for aircraft use = named in lawsuit when the aircraft crashes and my product was certified and on board.

  9. I have one in mine…just a cheap one that gets replaced every other year and tested with every oil change. In the golden olden days, the little spot CO detectors were stuck prominently on the panel. I have never had one of those alert (or turn brown), but then I have had an occasional exhaust pressure test that was not up to snuff and one crack in the muffler to pipe fitting caught at annual. I too have fresh air entering the cabin anytime the heat is on and usually when it is off, and carry and use oxygen at altitude. I don’t think a TSO’d CO detector is necessary as most of these meet some or other standard and the plaintiff’s attorneys are probably eager to pounce on any that fail.

  10. So why don’t more GA pilots use detectors?

    Years ago I bought a little tag one from an aircraft parts dealer, price just a few dollars, gave it to a friend who had a puff-cooled VW van.

    (That’s what I call the air-cooled VW engine, air through a shroud was commonly used as a heater, with obvious risk. Chevrolet Corvairs had optional gasoline fired heater, as did many old aircraft like DC-3s. VW kept peddling that underpowered engine through the 1981 Vanagon series after which it was liquid cooled, even later in Beetles in Mexico and elsewhere despite many countries switching to the Golf/Rabbit modern car in 1974.)

  11. If the person doing your annual inspection isn’t putting eyes on your entire exhaust system EVERY TIME the cowl comes off, a very candid discussion must occur! Ask your mechanic to show you your exposed, unshrouded muffler. If what you see doesn’t sit well, fix it or replace it!! No, it won’t be inexpensive but going to sleep at the wheel never ends well. Get to the root of the problem; don’t mandate/legislate a fix to a shortfall in maintenance. Being an A&P who has inspected hundreds of exhaust systems and found a couple that were “blown out” and more that were cracked, attention to detail and process must not waiver.

  12. Sad case was an experienced seaplane pilot from BC who crashed unexplainably in Australia.

    A doctor prodded crash investigators to check tissue for evidence of CO poisoning. Indeed, was in pilot and front seat passenger.

    A plate covering an access hole through firewall had not been properly re-installed, and exhaust manifold was leaking.

  13. How about trading the ELT for a CO detector. How many people have been saved by ELT’s in the past 20 years? If you need something, you can carry a Spot or inReach (both much better than an ELT).

  14. At home:
    – combined CO-‘smoke’ detectors
    – CO detector plugged into wall outlet

    I knew someone who had the latter outside bedroom door, it registered almost at its threshold when smoke from a burning furnace filter filled the house.

    Of course wall outlet is low, smoke rises, I have not checked if CO does.

    • Carbon monoxide (molecular wt. 28) has almost the same density as normal air (28.8), so location of a detector in a house is not that critical.

  15. Regs are written in blood. Even if not much blood, it’s still blood. I’m sure there will be a cost-effective solution out there. Personally while the odds are low, there is a good feeling of having a detector available. You could make the same argument with seatbelts in GA aircraft: while odds are low that you’ll need them on any given flight, they aré absolutely life savers (esp multipoint harness types) when you do require them.

  16. I was amused to note that the recommendation excluded open-cockpit airplanes. Contrary to belief, it *is* possible to get CO poisoning in an open cockpit plane…the cockpit area is low pressure. Have a friend who got a bad case in a Starduster. I carry a portable unit in my Fly Baby, and have measured transients of 30 ppm (new exhaust system since). Actually got CO poisoning once (as a pax in a Mooney) so I’m a bit more cautious than some. Passed out (on the ground) after we landed.

  17. Carbon monoxide is an insidious and deadly compound that disables and kills hundreds of people each year – mostly from poorly vented space heaters or home furnaces. Modern automobiles have much lower CO emissions due to their catalytic converters than our old air-cooled airplane engines. An aircraft engine can easily produce fatal levels of CO, especially if the mixture is set to run rich. While it is easy to blame exhaust leaks on poor annual inspection practices, a system can develop a leak in an exhaust gasket or a pipe can crack a week after the annual that might not see the light of day for another 51 weeks. The NTSB recommending that CO detectors should be in all piston aircraft is a reasonable request considering the potential consequences of exposure. The problem comes in how the FAA chooses to proceed. Yes, if they go the TSO route for an installed detector it will be expensive. There are already several available in the range of $500-800 dollars, plus installation. If they choose to accept a portable unit that the pilot can carry, good ones range from $100-300 dollars. And, yes, Aviation Consumer did a review of available detectors several years ago, but it probably needs to be updated by now.

    It might also depend on which standard the FAA uses as the criteria for what is “acceptable”. There are three main governing bodies that regulate CO exposure levels – OSHA, NIOSH (OSHA’s parent agency) and ACGIH (the national body of Certified Industrial Hygienists). Each one has a level they consider acceptable for chronic eight hour exposure. They are as follows:

    ACGIH – 25 ppm for 8 hours, 400 ppm 15 minute exposure.
    NIOSH – 35 ppm 8 hr, 200 ppm short term exposure ceiling.
    OSHA – 50 ppm 8 hr, 200 ppm ST Ceiling.

    However, one has to recognize that all these are measured at sea level. At 10,000 feet, the lower level of available oxygen in the air could make those levels unsafe for long-term exposure. As with blood alcohol levels at altitude, CO in the blood could have increased effects on judgement and motor skills. If the FAA simply chooses to consider a detector that has either OSHA or NIOSH certification, then the portable units readily available from Sporty’s or other aviation vendors would do just fine. As far as I know, even the permanently installed units on the market still use either the OSHA or NIOS standards, so I doubt that the FAA would want to choose a different standard. In any case, if you choose to carry a portable detector, be aware that any level above about 10 ppm should be immediately investigated unless it is a transient level that lasts just a few minutes. For example, in my Cardinal RG, I often get a spike in CO when the gear is extended on approach, but usually disappears in a couple minutes. And finally, don’t bother with the passive “spot” detector badges. They all have a short shelf life and, being passive, don’t alert you to short term high levels of exposure that could be life threatening. Sorry to be so long-winded. 🙂

    • Here’s a list I created from various sources of carbon-monoxide exposure limits and health effects. One thing to consider when looking at this list is partial impairment. Don’t just consider alive/dead, or conscious/unconscious, but think of how you would feel trying to shoot an approach after breathing 200ppm of CO for a couple of hours? How many landing accidents are listed as due to “pilot error” such as fatigue, illness, etc., that may actually be due to small CO leaks?

      Level of CO Health Effects, and Other Information
      ======= =====================================
      0 PPM Normal, fresh air.
      9 PPM Maximum recommended indoor CO level (ASHRAE).
      10-24 PPM Possible health effects with long-term exposure.
      25 PPM Max TWA Exposure for 8 hour work-day (ACGIH).
      50 PPM Maximum permissible exposure in workplace (OSHA). FAA Certification Limit.
      100 PPM Slight headache after 1-2 hours.
      200 PPM Dizziness, nausea, fatigue, headache after 2-3 hours of exposure.
      400 PPM Headache and nausea after 1-2 hours of exposure. Life threatening in 3 hours.
      800 PPM Headache, nausea, and dizziness after 45 minutes; collapse and unconsciousness after 1 hour of exposure. Death within 2-3 hours.
      1000 PPM Loss of consciousness after 1 hour of exposure.
      1600 PPM Headache, nausea, and dizziness after 20 minutes of exposure. Death within 1-2 hours.
      3200 PPM Headache, nausea, and dizziness after 5-10 minutes; collapse and unconsciousness after 30 minutes of exposure. Death within 1 hour.
      6400 PPM Death within 30 minutes.
      12,800 PPM Immediate physiological effects, unconsciousness. Death within 1-3 minutes of exposure.

  18. Better idea: Training and culture that gets pilots to use portable units.

    Why this will not happen: If the demise of middle class aviation in this country isn’t a government involved conspiracy (it’s not really), it sure looks EXACTLY like one.

    I don’t care any more who or why, just what. (Totally untrue, I’m fascinated with what I believe is a bellwether for our country). I say no to any more requirements with the certification, tracking, and tort taxes involved.

  19. As someone who is wanting to learn to fly I have a question on this… I thought there were some planes like the Diamond DA62 and others that it really isn’t possible to get CO from the engines in the cabin? Engines on the wing instead of in front and I thought heat was electric and didn’t touch the engines in any way. If that is correct then does it make sense to require such a thing?

  20. Give me a break!

    Resolve a maintenance issue by mandating another maintenance issue.

    As pilots, the safety of your passengers and others is your responsibility.

    Be responsible, and stop accepting the nonsensical idea that government has your best interest at heart.

    The denizens of the NTSB are primarily concerned about their employment, and that requires accidents.

    • How can I ensure the safety of me and my passengers with no detection? Help me understand how you do it. It’s obvious that most of us have just ridden along just grateful that the occurrence is so low. Other than detection systems I just don’t see how your comment makes any sense.

      Other than a knee-jerk libertarian comment that is better suited for other topics, just not this one.

      • Well, you don’t do it by relying on the government to mandate equipment.

        Are you going to wait for the FAA, or get off your butt and fulfill your responsibilities?

        1. FAA rarely accepts NTSB equipment recommendations.

        2. The issue is failure to properly maintain the exhaust system, inspect and maintain as necessary, as is your responsibility.

        3. If you feel unable to fulfil that responsibility, step up and purchase/install detection equipment, then maintain it.

        4. Consider limiting your flight experience to single seat aircraft so as to ensure that you don’t place passengers in jeopardy.

        I must apologize if I have been too diplomatic to make my point clearly, but I can assure you that I am taking assertiveness training.

      • Buy a $100 portable battery powered amperometric detector. There are several models available with appropriate alarm levels and short dwell times. I attached one to my center console where the flashing lights will attract your attention if there is potentially hazardous CO present. Replace it every 5 years when it hits the expiration date. The last thing I need is a bulky, expensive, difficult to maintain, TSOed FAA panel-mount unit. There are good alternative available now.

  21. When you are a hammer, everything looks like a nail – – and when you are a rule factory, everything looks like an opportunity for a new rule.

    Not saying having a CO detector in your plane is a bad idea in itself, but as the ongoing COVID nightmare demonstrates, how you elect to implement a not-bad idea needs to be balanced against the undesired effects it produces. And there are always undesired/undesirable effects.

  22. Top of the line Portable CO detector is under $200…
    Make it mandatory and certified installed… $2000 before installation.

  23. When I was assigned to S61N’s (Part 135) we used CO detectors similar to Save A Life. We changed them out every month which is overkill for GA. Those CO detectors were easy to change and they worked. If you want to install a CO detector or some other safety equipment then refer to FAA PS-AIR-21.8-1602 NORSEE. This route is far simpler to get installed as well as maintain than getting it done through certification.

  24. NTSB needs to leave GA alone, these guys/gals need to concentrate on safety for the “paying” flying public not the private owners flying there 2 and 4 seat aircraft. This is total government over reach, the exhaust system is already covered under the annual inspection rules and inspection criteria. To require another expensive burdensome system that has its own set of failures would be an obvious lack of understanding and competence on the part of the rule-makers.

  25. Those little dots on the panel are easy to ignore, and impossible to see in the dark. When I first heard about them, I bought a portable CO detector in 2018 for peace of mind. It hangs on the unused microphone holder on the co-pilots side, secured with velcro. When I taxi with the window open and conditions are right it beeps. When it does beep while taxiing, it typically indicates 25 or 50 ppm. After takeoff I find it reassuring to see it drop down to 0 over the next 10-15 minutes.

    How many of you turn on the heat at altitude and notice that hot exhaust system odor? I’ll occasionally glance at the CO detector to make sure that just heat is getting in. That’s peace of mind. Should it be required? I don’t know. $130 for a portable unit isn’t too bad. My unit complained calibration due a month ago, so I happily sent it in to the factory for calibration. At $70 or so for recalibration, I’m fine with that. I want that damn thing working. I’d say if the FAA mandates it, I don’t care. I want one any way. I just hope that if they do, they don’t require a TSO’d $2,000 one.

    Exhaust leaks happen. Read the article about the Mooney pilot a few years ago who woke up in a snowy field one night and had no idea how he got there.

  26. Many more people die per year due to drunk drivers. Why not mandate a breathalyzer on board each vehicle that must be utilized before the engine can be started. Now talk about saving lives NTSB!!

    “Drunk driving causes more than 10,000 deaths every year, about 1/3 of all traffic-related deaths. In a recent year, more than 230 children were killed in drunk-driving crashes, the NHTSA reports. Drinking and driving costs more than $44 billion in deaths and damages annually.Jul 26, 2021”

  27. I recently added a Gardian remote mounted CO Detector. To be honest the $500 price tag was a little shocking at first but when you put it into perspective it’s a couple of tanks of gas and provides a lot of peace of mind.

    I have a JPI 930 that I added last year along with a new engine and complete panel upgrade. The unit interfaces with both the JPI and my Audio panel. The JPI displays the CO levels real time while in flight and I was surprised to see the CO levels change in my cabin based on flight configuration. The levels would range between 0 PPM and as high as 10-12 PPM. I never really had any idea the levels would be that high since I previously only had the ultra high tech dot indicator which to be honest is something I never paid any attention to other than at annual time.

    I think for the price it’s a worthwhile investment for the level of safety and peace of mind it brings. If $500 is a deal breaker then maybe flying isn’t the best choice for some.

    • You’d have a point if it was only one $500 decision. Added on to all the other, non optional decisions (many of which have made us decidedly less safe), and I’m just unwilling to accept such logic anymore.

  28. Mandating a panel mounted CO detector is a bad idea. Many airplanes don’t have room for one in the panel – mine included. I carry a portable TOCSIN unit from Sporty’s, which is perfectly adequate for $169.95. As far as the value of an electronic CO detector, there’s no question in my mind. Six years ago I flew my airplane from NC to ID to do some back country flying. When I had to cross the mountains at 10,000 MSL it got cold enough to apply cabin heat. My portable CO detector went off almost immediately and stopped when I shut off the heat. I toughed it out until I landed in ID and had a mechanic look at the exhaust. He found a crack in one of the welds and a deformed exhaust header pipe on one of the cylinders. Both were allowing CO to escape into the engine compartment and slip through small gaps around the heat muff hose firewall port into the cabin when cabin heat was applied. The mechanic re-formed the header pipe and had the crack welded, which fixed the problem. Cracks in exhaust welds are fairly common, especially due to more vibration associated with a 4-cylinder engine vs. a 6-cylinder engine. Although the exhaust system is inspected at every annual, cracks can occur between annuals depending on the amount of flying done. The bottom line is that you should have an electronic CO detector when you fly but portable units are adequate. Mandating a panel-mounted unit would make for a much more expensive installation without increasing safety over a portable unit.

  29. I use those Spot detectors, they are cheap, reliable and I replace them often. If the FAA wants to mandate CO detectors, the spot type of detectors should be able to be used, even if they have a short shelf life and service life. I’ve had CO issues and they darkened right up. I had to lengthen my exhaust pipes twice, to finally rid my cockpit of CO.

    • The spot detectors are virtually useless. I won’t use them in a chemistry laboratory, and certainly not in a GA aircraft. An amperometric detector has a lower and faster alarm threshold, if more precise and definitive in measurment, and has a longer useful lifetime.

  30. An FAA requirement is only likely to make compliance more expensive and burdensome. Don’t get me wrong. Everyone should be flying with an amperometric CO detector in the cockpit with low alarm thresholds and short dwell times. There are several small battery powered models available for around $100 that suit this need perfectly well. Once the FAA gets involved, compliance will only get more difficult.