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Post Crash Fires

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POST IMPACT FIRE


Article Information
Category: Fire Smoke and Fumes Fire Smoke and Fumes
Content source: SKYbrary About SKYbrary
Content control: EUROCONTROL EUROCONTROL

Definition

Post Crash Fires are fires which occur after an aircraft has crash landed or has impacted obstacles or other aircraft during ground movement, runway incursion, or runway excursion.

Description

On impact with the ground or an obstacle with high kinetic energy, which results in structural break-up of the aircraft, a fire can start if fuel comes into contact with hot surfaces. Equally, damage to containers carrying flammable material being carried as cargo on an aircraft (fuels, chemicals, explosives etc) may ignite as a consequence of impact, contact with hot surfaces or, in the case of unstable chemicals, the atmosphere.

Fire can spread quickly to the fuselage and through the cabin generating heat, smoke, and toxic decomposition products. If the temperature of trapped smoke and gasses reaches the auto-ignition temperature, Flashover will occur, rapidly engulfing the aircraft the aircraft in flames.

Effects

Depending upon the severity of the crash, and any resulting fire, the effect on the aircraft can vary from minor damage to total hull loss. Similarly, the potential casualty consequence of a crash/fire event ranges from no injuries to the loss of life of all on board. Collateral damage and casualties are possible dependent upon the location of the crash.

Defences

  • Aircraft Design. Aircraft structures and fuel systems can be designed to minimise the quantity of fuel spillage
  • Fuel - Virtually all large passenger aircraft burn jet fuel and not avgas. The much higher flashpoint of jet fuel reduces the potential for a post crash fire.

Solutions

  • Aircraft Evacuation - Expeditious emergency evacuation of the aircraft. Consequently, robust training of the cabin crew in evacuation procedures is essential.
  • Engine ShutdownTo minimize the potential for injury during the evacuation, the flight deck crew will take all necessary actions to shut down and secure the aircraft engines, shutting fuel valves and cocks. Depending upon the degree of damage to the aircraft, this may not always be possible.
  • Rescue and Fire Fighting Services - Rescue and Fire Fighting Services (RFFS) are instrumental in saving lives and minimizing the damage from a post crash fire. If the crash occurs within the airfield boundaries, the initial RFFS response units will be on site within a very short period of time; often less than a minute. Response to an off airfield crash may take considerably longer due to the time it may take to locate the crash and to the accessibility of crash site.

Contributing Factors

Large amounts of fuel can be carried by modern aircraft and an aircraft crash has the potential to rupture the fuel tanks. Should the spilling fuel be exposed to a spark or open flame a fire may occur. This is particularly true of fuels with low flashpoints such as avgas. While jet fuels have a higher flashpoint and are less susceptible to sparks, exposing them to operating engines or to hot engine components may raise the temperature of the fuel to its auto-ignition point and a fire will result.

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