Which of the following is considered an external fire cause?

• A. Any unusual circumstances outside the aircraft, either during the flight or on the ground
• B. Dropped cigarettes
• C. Electrical faults
• D. Galley oven

Answer: (A)

External fire causes are fires that originate outside the aircraft, during flight or on the ground, rather than from systems or equipment inside. The statement describes circumstances outside the aircraft, which fits this definition because it covers ignition sources or events occurring off the aircraft that could start a fire. The other options point to internal sources: a cigarette that is dropped and burns inside the cabin, electrical faults within the aircraft’s electrical system, and a galley oven—an onboard appliance. Since the question asks for an external fire cause, the description of external circumstances outside the aircraft is the best fit.