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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

the fire can spread through the cabin generating heat, smoke, and toxic decomposition products. Hot combustion products rise from the fire to form a distinct, hot, smoky layer just below the ceiling which deepens as the fire continues to burn. Burning side and ceiling panels fall and ignite seats resulting in the total conflagration of the cabin interior. This in turn raises the temperature of the trapped smoke and gasses towards their auto-ignition point. On reaching the auto-ignition temperature, Flashover occurs.

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
  • 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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