Thursday, October 18, 2012

Carbon Monoxide in Aircraft

                       A helicopter was recently reported as having made a precautionary landing after the crew were alerted to a carbon monoxide warning. Any indication of carbon monoxide (CO) entering the cockpit should be treated extremely seriously; the colourless and odourless gas is with justification referred to as ‘the silent killer’.
                       In 2001 the crew of a PA24 were killed when their aircraft spun into the ground 12 minutes after take-off. The accident investigation concluded that the occupants had been poisoned by CO leaking from a failed exhaust manifold into the cockpit. The aircraft was not carrying any detectors which could have warned of the presence of carbon monoxide. CO can usually only be recognised in an aircraft by associated engine exhaust smells. Symptoms are subtle, similar to alcohol intoxication or perhaps the resulting hangover with its attendant headache. As previously described in SafetySense leaflet 24 ‘Pilot Health’ (now withdrawn but hopefully shortly to be replaced), the best way to deal with CO poisoning is to prevent exposure in the first place, but if you do suspect its presence when in flight, increase ventilation, land and try to get an engineer to trace any sources.
               Every occupant in an engine-powered aircraft is at risk of carbon monoxide poisoning, which can be DEADLY! Carbon monoxide (CO) is colorless, odorless, and most importantly, POISONOUS. CO binds with the hemoglobin in your blood, displacing the oxygen it's supposed to carry throughout your body. This robs your circulatory system of the ability to do its job. CO is also a cumulative poison, so you don't have to be exposed to high levels all at once to have serious side-effects from the exposure. Initially, the effects are easily confused with other things... headaches, nausea or vomiting, and fatigue. As exposure continues, this progresses to severe headaches, drowsiness, confusion and impaired judgment, and a fast heart rate. Finally, victims may suffer convulsions, lose consciousness, their cardio-respiratory system will shut down, and they will die as a result. Sadly, even if the victim is rescued, there remains a high risk of permanent brain and organ damage and lifelong impairment.
        CAA recommend that pilots carry one of the CO monitors on the market, which are usually primarily intended for home or caravan use, and include it in their normal scan pattern. Paper sensors are easily contaminated by other fumes, so consider changing them more frequently than their markings would suggest. Electronic detectors often have several functions in addition to a basic warning, and care should be taken that they are set up to give warnings and alarms in a timely and appropriate manner.

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