Headache and drowsiness with cabin heat on
On a winter afternoon you are flying VFR from Rosh Pina (LLIB) to Herzliya (LLHZ) at 4,500 ft. The cabin heat has been on for 40 minutes because the outside air temperature is −2°C. Your passenger complains of a headache and nausea. You feel drowsy and slightly dizzy, and you initially put it down to turbulence and a short night of sleep. You slept about five hours. The aeroplane has an exhaust-shrouded muffler heater. The windows are closed and there is no noticeable smell in the cabin. You are 35 minutes from LLHZ and 15 minutes from a suitable aerodrome behind you. There is no turbulence now and the autopilot is not fitted.
1. What is the likely problem, and what immediate actions would you take?
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The combination of headache, nausea, drowsiness and dizziness with cabin heat on strongly suggests carbon monoxide poisoning, not simple fatigue. CO is odourless, so the absence of smell does not rule it out. Immediate actions: shut off the cabin heat, open fresh-air vents and windows, and do not continue with the heat on. If oxygen is available, use it. Descend if practical and avoid exertion. Tell ATC you have a suspected CO problem and need priority to land. Do not wait to see whether symptoms improve in the air. The passenger should also receive fresh air and oxygen if available. The priority is to land as soon as possible, not to complete the planned flight.
2. Which aerodrome would you choose, and what would you do after landing?
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Choose the suitable aerodrome 15 minutes behind, not LLHZ 35 minutes ahead. The shorter exposure is safer, and the decision should not be driven by the convenience of the destination. Fly a normal approach, but allow for the possibility that your judgement and coordination are impaired. After landing, shut down, get both occupants out into fresh air, and seek medical advice; CO can cause delayed effects. Do not fly again until the aircraft heater and exhaust system have been inspected for a cracked muffler or leaking heat exchanger. Report the occurrence and make a maintenance entry. If symptoms are severe, call emergency medical services.