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Post Crash Fires

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Category: Fire Smoke and Fumes Fire Smoke and Fumes
Content source: SKYbrary About SKYbrary
Content control: SKYbrary About SKYbrary

POST IMPACT FIRE

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

In the event of an impact with the ground or an obstacle, which results in structural damage to an aircraft, a fuel and/or oil fed fire can start if fuel comes into contact with ignition sources. Equally, if flammable material, being carried as dangerous goods on a Civil aircraft or as cargo by a military aircraft, is damaged or the containment compromised, it may ignite as a consequence of impact, contact with hot surfaces or, in the case of spillage 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 and an aircraft fuselage can be rapidly engulfed by 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.

For aircraft with a maximum certified take-off weight of 5700 kilograms or less, post-impact fire contributes significantly to injuries and fatalities in accidents that are otherwise potentially survivable.

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

  • Preparation of the aircraft - where the crash landing is anticipated, for example if an off-field landing is necessary or the aircraft has a landing gear malfunction, then there are several things that can be done to reduce the probability and severity of a fire:
    • Dump Fuel - if time and aircraft design allow, dump to reduce the amount of fuel and improve the handling of the aircraft. For aircraft not fitted with Fuel Dump capability, the aircraft can loiter in the vicinity of the landing airfield to burn gas. Note that, in the case of an onboard fire, smoke, or fumes, any delay to landing the aircraft, inclusive of dumping fuel, should not be considered.
    • Isolate fuel systems - close crossfeed valves.
    • Cabin - Prepare the cabin for emergency landing.
    • Cargo - Jettison flammable cargo if possible and practical.
  • Aircraft Evacuation - Expeditious emergency evacuation of the aircraft will minimise the loss of life in the event of a post crash fire. Consequently, robust training of the cabin crew in evacuation procedures is essential.
  • Engine Shutdown & Aircraft Systems - To minimize the potential for injury during the evacuation, the flight deck crew will take all necessary actions to shut down and, using fire handles, condition levers, or fire push button (depending on aircraft type) isolate the aircraft engines. 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.

Accidents and Incidents

A selection of incidents from the SKYbrary database related to Post Crash Fire:

  • C30J, en-route, northern Sweden 2012 (On 15 March 2012, a Royal Norwegian Air Force C130J-30 Hercules en route on a positioning transport flight from northern Norway to northern Sweden crossed the border, descended into uncontrolled airspace below MSA and entered IMC. Shortly after levelling at FL 070, it flew into the side of a 6608 foot high mountain. The Investigation concluded that although the direct cause was the actions of the crew, Air Force procedures supporting the operation were deficient. It also found that the ATC service provided had been contrary to regulations and attributed this to inadequate controller training.)
  • B732, vicinity Resolute Bay Canada, 2011 (On 20 August 2011, a First Air Boeing 737-200 making an ILS approach to Resolute Bay struck a hill east of the designated landing runway in IMC and was destroyed. An off-track approach was attributed to the aircraft commander’s failure to recognise the effects of his inadvertent interference with the AP ILS capture mode and the subsequent loss of shared situational awareness on the flight deck. The approach was also continued when unstabilised and the Investigation concluded that the poor CRM and SOP compliance demonstrated on the accident flight were representative of a wider problem at the operator.)
  • C177, vicinity Calling Lake Alberta Canada, 2000 (On 30th May 2000, a Cessna 177 lost control shortly after take-off from Calling Lake, Alberta, Canada, crashed and suffered a post crash fire.)
  • LJ35, Lyon France, 2000 (On 2 May 2000, the crew of a LJ35 lost control of the aircraft, as a result of incorrect manual flying inputs, and crashed just before touchdown at Lyon, following an unstable single engine approach.)
  • DH8D, vicinity Buffalo NY USA, 2009 (On 12 February 2009, a Bombardier DHC-8-400 on a night ILS approach to Buffalo-Niagara airport departed controlled flight and was completely destroyed by ground impact and subsequent fire. The Investigation found that the Captain had failed to effectively manage the flight and that his consequent response to a resulting stick shaker activation had been completely contrary to applicable procedures and his training, leading directly to the loss of the aircraft. The aircraft operator’s normal approach procedures were also determined to be inadequate and it was noted that prior to the accident, sterile flight deck procedures had been comprehensively ignored.)

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