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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.)
  • A332, vicinity Tripoli Libya, 2010 (On 12 May 2010, an Afriqiyah Airways Airbus A330 making a daylight go around from a non precision approach at Tripoli which had been discontinued after visual reference was not obtained at MDA did not sustain the initially established IMC climb and, following flight crew control inputs attributed to the effects of somatogravic illusion and poor CRM, descended rapidly into the ground with a high vertical and forward speed, The aircraft was destroyed by impact forces and the consequent fire and all but one of the 104 occupants were killed.)
  • T154, vicinity Smolensk Russian Federation, 2010 (On 10 April 2010, a Polish Air Force Tupolev Tu-154M on a pre-arranged VIP flight into Smolensk Severny failed to adhere to landing minima during a non precision approach with thick fog reported and after ignoring a TAWS ‘PULL UP’ Warning in IMC continued descent off track and into the ground. All of the Contributory Factors to the pilot error cause found by the Investigation related to the operation of the aircraft in a range of respects including a failure by the crew to obtain adequate weather information for the intended destination prior to and during the flight.)
  • B742, Düsseldorf Germany, 2005 (On 24 January 2005, an Atlas Air Boeing 747-200F overran the end of the landing runway at Düsseldorf after runway braking action notified just prior to landing as medium due to snowfall unexpectedly deteriorated after the snowfall intensified. The overrun led to collision with ground obstacles and engines 2 and 3 caught fire. Escape slide malfunction at the forward left hand door led to an alternative non standard crew evacuation route being used. Significant damage to the aircraft resulted in it being declared a hull loss. The Investigation took almost 8 years to complete and publish.)
  • B744, Taipei Taiwan, 2000 (On 31 October 2000, the crew of a Singapore Airlines Boeing 747-400 taxiing for a night departure at Taipei in reduced (but not 'low') visibility with an augmenting crew member present on the flight deck failed to follow their correctly-confirmed taxi instructions and commenced take off on a partially closed runway. The subsequent collision with construction equipment and resultant severe post crash fire destroyed the aircraft killing over half the 170 occupants and injured 71 others. All three flight crew survived.)

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