Fire In Flight

16.fire-in-flight. Fire In Flight

An in-flight fire is one of the most time-critical emergencies a pilot can face. Smoke, fumes, and flames degrade the airframe, incapacitate occupants, and can destroy flight controls within minutes. The pilot's task is to (1) identify the source, (2) attack it with the appropriate procedure, and (3) get the airplane on the ground as quickly as practical. Indecision is more dangerous than imperfect action — a controlled forced landing is preferable to an uncontrolled descent in a burning airplane.

Sources of In-Flight Fire

Fires generally fall into four categories, each with a tailored response:

• Engine fire — usually caused by a broken fuel/oil line, induction backfire during start, or exhaust system failure. Indicated by visible flames from the cowl, smoke through the vents, an oil-smoke smell, or a sudden engine roughness with rising CHT/oil temperature.
• Electrical fire — caused by a short, overloaded wire, or failed component. Indicated by the acrid smell of burning insulation, smoke from behind the panel, popped breakers, or smoke from avionics.
• Cabin/cockpit fire — discarded cigarettes (in older aircraft), heater malfunctions, faulty wiring behind upholstery, or passenger-carried items (lithium batteries are an increasing threat).
• Wing fire — typically a fuel leak ignited near a navigation/landing light or exhaust, or a ruptured fuel cell.

General Response Principles

For any in-flight fire, the immediate priorities are to isolate the fuel or ignition source, extinguish the fire, clear smoke from the cabin, and land as soon as possible. Always follow the manufacturer's POH/AFM checklist for the specific airplane — the items below are representative.

Engine Fire In Flight

1. Mixture — IDLE CUTOFF
2. Fuel selector — OFF
3. Fuel pump — OFF (check POH; some airplanes leave it on briefly)
4. Cabin heat and air vents — CLOSED (to prevent smoke entry)
5. Airspeed — Increase to a value that may blow the fire out (often Vno or higher per POH); do not exceed VNE
6. Execute an emergency descent and land as soon as possible — do not attempt a restart

Do not pitch up or slow down; the slipstream is your strongest extinguisher. If a forced landing is unavoidable, plan for power-off configuration and minimum-energy touchdown.

Electrical Fire / Smoke In Flight

1. Master switch — OFF
2. All electrical switches — OFF
3. Vents/cabin air/heat — CLOSED initially (closing prevents feeding the fire), then opened to evacuate smoke after the fire is out
4. Fire extinguisher — ACTIVATE (use a Halon or other approved Class C extinguisher; never water on electrical fires)
5. After fire is extinguished and cabin ventilated, if continued flight is essential, individually re-energize critical busses and components one at a time, leaving the faulted circuit OFF
6. LAND AS SOON AS PRACTICAL

Wearing supplemental oxygen with a smoke mask, if available, allows the pilot to remain functional in dense smoke.

Cabin Fire

1. Identify the source
2. Master switch — OFF if electrical in origin
3. Fire extinguisher — ACTIVATE
4. After extinguishing, ventilate the cabin (open vents, side window, or storm window per POH)
5. LAND AS SOON AS POSSIBLE

Cabin fires often reignite — keep the extinguisher in hand and monitor the area. Lithium-battery thermal runaway requires drowning the device in any non-flammable liquid (water, soft drinks, coffee) and isolating it in a metal container if practical.

Wing Fire

Use the landing/navigation/pitot heat switches OFF to remove ignition sources. Sideslip away from the burning wing so flames do not impinge on the fuselage and cabin. Land as soon as possible.

Use of the Fire Extinguisher

The acronym PASS applies: Pull the pin, Aim at the base of the fire, Squeeze the handle, Sweep side to side. After discharging a Halon extinguisher in a closed cabin, ventilate as soon as the fire is out — Halon byproducts are toxic.

Land As Soon As Possible vs. Practical

FAA terminology distinguishes the two: "as soon as possible" means land at the nearest suitable airport or off-airport site without delay. "As soon as practical" allows the pilot some discretion regarding which airport, weather, and runway are most appropriate. An active in-flight fire is virtually always an "as soon as possible" situation, justifying declaration of an emergency under 14 CFR 91.3(b) and any deviation from the FARs necessary to get safely on the ground.

Summary

Recognition speed determines the outcome. The pilot must memorize the engine-fire and electrical-fire procedures from the POH, know where the extinguisher is mounted, brief passengers on its use, and never hesitate to declare an emergency. A burning airplane will not get better with altitude — every second spent troubleshooting at cruise is a second not spent descending toward a runway.