If carbon monoxide is suspected in the cabin, the IMMEDIATE pilot action is to

Choices

• land at the destination as planned.

  Continuing to destination risks incapacitation and crash.

• ✓ TURN OFF the cabin heat (which usually muxes exhaust gas into cabin air via a cracked heater muff).correct

  OPEN vents/windows for fresh air, descend to lower altitude (more O2 for the body), and land ASAP. declare medical emergency. CO source in GA aircraft is almost always a cracked exhaust manifold leaking into the heater muff. Turn heat OFF immediately to break the leak path. Open vents (fresh air dilutes CO). Descend (lower altitude = more O2 to compensate for COHb-reduced O2 carrying capacity). Declare medical emergency (CO impairment is real — judgment fades fast). Treat as life-threatening.

• increase cabin heat to dilute the CO.

  Heat is the SOURCE — not a dilution mechanism.

• continue but breathe through a wet rag.

  Wet rag doesn't filter CO.