Carbon Monoxide Poisoning

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 spending time around smokers, thereby reducing your tolerance before takeoff
• Even the direction of the wind relative to a running engine in the air during certain maneuvers, but more likely on the ground around other aircraft, can be a source

Recognizing Carbon Monoxide Poisoning:

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• 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 ability for blood to transport oxygen
    • As little as 10% Carboxyhemoglobin (Carbon Monoxide in the blood) decreases peripheral and night vision
  • Symptoms will mirror that of hypoxia as an increase of CO in the blood implies you are 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

• Carbon Monoxide Detection:

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  • Due to its result from incomplete combustion, there will usually be odors or colors which can provide cues
    • Example: the smelling exhaust is an indication of a leak and possible contamination
  • Since Carbon Monoxide is odorless, it may be challenging 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
    • Especially when impaired, detectors can trigger a pilot's cognative ability to recognize the problem
    • Carbon Monoxide detectors come in many designs but generally speaking; you'll have the choice of either passive or electronic detectors

    • Passive Detectors:

      • The Quantum Eye Carbon Monoxide Detector [Amazon] is the most basic choice [Figure 2]

        • Advantages of Passive Detectors:

          • Low cost
          • Works independently of electrical power

        • Passive Detector Disadvantages:

          • Pilots must monitor the indicator 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 [Amazon] are the more advanced types of detectors [Figure 3]

        • Electronic Detector Advantages:

          • Audible alarms when carbon monoxide rises
          • Convenient enough to be carried at home or in a vehicle

        • Electronic Detector Disadvantages:

          • Generally more expensive than passive detectors
          • Requires batteries
  • It is highly recommended (though not required by the FAA) to have a CO detector
  • It is important that the detector be installed in accordance with manufacturer recommendations

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Immediate Action and Treatment:

• If detected or suspected CO is entering the cabin, perform the appropriate immediate actions
• Identify possible sources and attempt to isolate them
• Open-air vents, and attempt to flush the cabin with fresh air
  • CO exposure is compounding and takes along time to get rid of
  • After removal from CO source, the body only removes about 0.5% 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!
• Once resolved, have the aircraft inspected by a certified mechanic before its next flight to determine the source of the problem
• Once the situation has been resolved, have the aircraft inspected by a certified mechanic before its next flight

Carbon Monoxide Prevention:

• The straightforward statement is to follow appropriate maintenance procedures
• Carry a personal carbon monoxide detector [Amazon], especially when renting
• Pilots must pay special attention to the sources of carbon monoxide in the fall and winter months as damage may have occurred months before, but it does not manifest itself until cold weather arrives
• Most important is a thorough preflight to find potential sources
• Treat CO posioning as a constant possibility, as it often occurs throughout the year across all geographic locations

Carbon Monoxide Case Studies:

• National Transportation Safety Board (NTSB) Identification: CHI96LA101:
  • The NTSB determines the probable cause(s) of this accident to be: An inadequate annual inspection by maintenance personnel, a deteriorated muffler, and pilot incapacitation due to carbon monoxide
• National Transportation Safety Board Identification: ANC16FA065:
  • The NTSB determines the probable cause(s) of this accident to be: The pilot's severe impairment from carbon monoxide poisoning in flight, which resulted in a loss of control and a subsequent collision with trees and terrain

Carbon Monoxide Poisoning Knowledge Quiz:

Conclusion:

• Carbon Monoxide Poisoning in a silent killer, mitigated through a few simple steps
• Although deadly, realize its not a sudden large exposure that is of primary concern, but rather the slow onset of symptoms that go unrecognized
• 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
• Symptoms are not linear and a pilot's cognative ability will be effected first
• Detectors are not infalible and may produce false positives
  • Unless easily determined to be a false positive, normalization of deviance develops when warnings are present but ignored with a quick explaination or denial of the problem
• Additionally, ensure the Carbon Monoxide detector is in serviceable condition
• Consider reviewing the Pilot Workshop promo regarding CO poisoning
• For more information, see the Federal Aviation Administration (FAA) brochure called Carbon Monoxide: A Deadly Menace
• Still looking for something? Continue searching:

References:

• Aeronautical Information Manual (8-1-4) Carbon Monoxide Poisoning in Flight
• Aircrat Owners and Pilots Association - How it works: Pulse Oximeter
• Avweb - Carbon Monoxide Detectors
• Federal Aviation Administration - Carbon Monoxide: A Deadly Menace
• Federal Aviation Administration - Detection and Prevention of Carbon Monoxide Exposure in General Aviation Aircraft
• Federal Aviation Administration - Pilot/Controller Glossary
• National Transportation Safety Board - NTSB to FAA: Require Carbon Monoxide Detectors in General Aviation Aircraft
• Reddit - Carbon Monoxide Scare