What should be done to cabin heat and air during an engine fire in flight?

During an engine fire in flight, it is crucial to turn the cabin heat off. The reason for this procedure is that the cabin heat system often utilizes air that is drawn from around the engine, which could potentially be contaminated with smoke or flames from the fire. By turning the cabin heat off, you minimize the risk of allowing the fire's heat and smoke to enter the cabin, thereby protecting the occupants from inhaling harmful fumes and heat exposure.

Ensuring that the cabin remains as safe as possible requires limiting any intake of air that may be affected by the fire. Keeping the cabin heat system off helps maintain a safer environment in the cockpit and cabin until the situation is resolved or the aircraft can be landed safely.