Carbon Monoxide Poisoning


  • Carbon Monoxide, chemically abbreviated as "CO," is one of the most common and toxic of substances in the aviation environment
  • Due to its properties as a colorless, odorless, and tasteless gas, it can quietly build, resulting in deadly consequences
  • It is therefore critical that pilots are able to recognize carbon monoxide poisoning
  • If discovered, pilots must apply immediate action to treat those symptoms before they get worse

Sources of Carbon Monoxide:

  • CO is a by-product of the incomplete combustion of carbon-containing materials, such as aviation fuel
  • While Carbon Monoxide poisoning can occur with or without environmental control operating, heating units are the most likely source of the problem
    • Most heaters in light aircraft work by air flowing over the manifold
    • Use of these heaters while exhaust fumes are escaping through manifold cracks and seals is responsible every year for several nonfatal and fatal aircraft accidents from carbon monoxide poisoning
  • It is possible to have a large amount of CO in your blood just by your environment to include polluted air and being around smokers, thereby reducing your tolerance before takeoff
Carbon Monoxide Symptoms
Figure 1: Carbon Monoxide Symptoms

Recognizing Carbon Monoxide Poisoning:

  • Carbon Monoxide Poisoning Symptoms:

    • Compounded with additional cues, knowing the symptoms, and recognizing them in your passengers, can be a key indicator
    • Carbon Monoxide has an affinity of 240 times that of oxygen which means it will more readily attach itself to your blood cells
    • Low concentrations over time can produce high blood concentration impeding the bloods ability to transport oxygen
      • As little as 10% Carboxyhemoglobin (Carbon Monoxide in the blood) can decreased peripheral and night vision
    • Symptoms will mirror that of hypoxia as an increase of CO in the blood implies you are actually suffering from hypemic hypoxia
    • Victims could expect: [Figure 1]
      • Sense of pressure in the head
      • Drowsiness
      • Dizziness
      • Roaring/ringing sensation of the ears
      • Confused and unable to think clear
      • Drunk appearance
      • Vomiting
      • Incontinent
      • Convulsions
      • Bounding pulse
      • Cherry red lips
      • Dilated pupils
      • Incapacitation
  • Aircraft Carbon Monoxide Detector
    Figure 2: Carbon Monoxide Detector
    Aircraft Carbon Monoxide Detector
    Figure 3: Hand-Held Carbon Monoxide Detector

    Carbon Monoxide Detection:

    • Due to its result from incomplete combustion, there will usually be odors or colors which can provide cues
      • Example: smelling exhaust is an indication of a leak and possible contamination
    • Since Carbon Monoxide is odorless it may be difficult to detect Carbon Monoxide until you or your passengers are experiencing symptoms, at which point any delay can be life threatening
    • Therefore, Carbon Monoxide detectors are cheap insurance which you would rather have and not need, than need and not have
      • Choosing a Carbon Monoxide Detector:

        • As demonstrated in the case studies, carbon monoxide is a life threatening poison
        • Carbon Monoxide detectors come in many designs but generally speaking you'll have the choice of either passive or electronic detectors
        • Passive Detectors:
          • A passive detector, such as the Quantum Eye Carbon Monoxide Detector are the most basic choice [Figure 2]
            • Advantages of Passive Detectors:
              • Low cost
              • Works independent of electrical power
            • Passive Detector Disadvantages:
              • Indicator must be monitored as it will not produce an alarm
              • Must be attached to something in view
        • Electronic Detectors:
          • Electronic detectors such as the Pocket CO Carbon Monoxide Detector are the more advanced types of detectors [Figure 3]
            • Advantages:
              • Audible alarms when carbon monoxide rises
              • Convenient enough to be carried at home or in a vehicle
            • Disadvantages:
              • Generally more expensive than passive detectors
              • Requires batteries

Immediate Action and Treatment:

  • Identify possible sources and attempt to isolate them
    • After removal from CO source, only about 0.5% is removed from blood every 4 hours
  • Use 100% oxygen and open windows to circulate fresh air
  • Monitor for further respiratory distress
    • Tell ATC that you suspect CO poisoning
    • Declare an emergency if you feel the situation warrants
  • Land as soon as possible!
  • If symptoms are severe or continue after landing, medical treatment should be sought
  • Once the situation has been resolved, have the aircraft inspected by a certified mechanic before its next flight

Carbon Monoxide Prevention:

  • The easy statement is to follow appropriate maintenance procedures
  • More than that however, is to check potential sources prior to every flight

Case Studies:


  • Carbon Monoxide Poisoning in a silent killer who's risk can be mitigated through a few simple steps
  • It is incumbent on the pilot to conduct a thorough preflight which includes the exhaust/heating components to spot irregularities
  • After CO poisoning, it can take up to 24 hours to recover
  • Especially in winter months, refresh your knowledge on Carbon Monoxide and conduct an extra thorough preflight
    • Remember, the heater system may have gone unused for months
  • Additionally, ensure the Carbon Monoxide detector is in serviceable condition
  • For more information, see the Federal Aviation Administration (FAA) brochure called Carbon Monoxide: A Deadly Menace