On 10 October 2006, a BAE Systems 146-200 being operated by Danish airline Atlantic Airways on a passenger flight from Sola to Stord overran the end of runway 33 at destination at a slow speed in normal visibility at dawn (but just prior to the accepted definition of daylight) before plunging down a steep slope sustaining severe damage and catching fire immediately it had come to rest. The rapid spread of the fire and difficulties in evacuation resulted in the death of four of the 16 occupants and serious injury to six others. The aircraft was completely destroyed.
An Investigation was carried out by the Accident Investigation Board Norway (AIBN). Both the Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) were recovered but upon examination were both found to have been heat-damaged beyond their design tolerance so that only the FDR yielded any information at all and that was of only limited use to the Investigation. It was noted that the aircraft commander was familiar with the airport, had qualified on the aircraft type in 2004 and served as a First Officer but had only five months command experience prior to the accident.
It was determined that the approach and touchdown flown with the aircraft commander as PF had been essentially normal but that none of the six lift spoilers which are designed to provide a significant element of deceleration on an aircraft not fitted with thrust reversers actually deployed when selected after landing. It was noted that neither the aircraft manufacturer nor the aircraft operator “had prepared specific procedures stating how the crew should act in a situation where the lift spoilers did not deploy” and that “the pilots had not trained for such a situation in a simulator”.
Non-deployment of the spoilers was immediately observed by the absence of expected and routinely-monitored annunciations but it was found that the aircraft commander had not associated this with the unexpectedly poor deceleration and had assumed that the cause was a fault with the brakes. Therefore, after initially selecting the alternate braking system to no better effect, he had applied the emergency brakes. It was noted that these brakes do not have anti-skid protection and the severity of their application had been such that the wheels locked leading to the initiation of reverted rubber aquaplaning on the un-grooved damp runway surface.
Directional control was lost during attempts to avoid the aircraft overrunning the end of the runway and it was found that the aircraft had left the end of the paved surface at a ground speed of approximately 15 - 20 knots and slid down a steep slope which began almost immediately. The uneven nature of the terrain and the abrupt stop at the bottom of it caused serious damage to the airframe and it was considered probable that leaking fuel was immediately ignited due to an electrical short circuit. It was evident from a video recording commenced soon after the fire started that the No 2 engine of the aircraft had continued to run for in excess of five minutes after the aircraft came to rest and this had increased the severity of the fuel-fed fire by causing the air turbulence in the vicinity and thus increasing the supply of oxygen to the fire.
The landing runway showing the touchdown point taken fro the Official Report
The landing runway LDA was noted as being 1200 metres followed by a paved Runway End Safety Area of 130 metres and then by just 4 metres of grass before the commencement of an uneven and rocky slope averaging a 30° gradient. It was established that at the time of the accident, the design of the RESAs at the airport was not in accordance with the applicable regulatory requirements and the Investigation considered that “there (was) a possibility that the aircraft might have stopped inside the safety area had the (RESA) been lengthened by 50 metres in accordance with the (latest regulatory requirements)”. It was also noted that the terrain around the runway was “significantly steeper than prescribed in ICAO Annex 14 SARPs and so promulgated in the AIPs entry for the airport. It was further noted that when renewing the airport’s technical and operational approval four months prior to the accident, CAA Norway had required improvement of the safety area by October 2008 but that no compensatory measures were required during this dispensation period prior to the improvements being made.
The Conclusions of the Investigation were that:
- “the event was a consequence of “the accumulated effect of three factors - the aircraft design, the airport and operational factors, which, seen as a whole, may have been unacceptable at the time of the accident” and
- “On its own, the failure of the spoilers to extend would not have caused a runway overrun. The aircraft might have stopped within the landing distance available with a good margin if optimum braking had been used”.
- the excursion could have been prevented by relevant simulator training, procedures and a better system understanding related to failures of the lift spoilers and the effect that it has on the aircrafts’ stopping distance.
Further detailed findings on survival aspects included the following:
- “in principle, all those involved had a chance of surviving the accident resulting from the excursion” but this prospect had been compromised by the rapid development of the fire and availability of only two exits - the left side flight deck sliding window and the rear left door - and the un-openable reinforced flight deck to cabin door which prevented cabin occupants evacuating via the flight deck.
- the inaccessible location of the crash scene and the prevailing circumstances at it meant that although the Rescue and Fire Fighting Services arrived in the vicinity promptly, they were unable to play any useful role during the critical initial minutes after the crash.
- Non compliance of the airport with State regulatory requirements and the notified difference from ICAO Annex 14 SARPs in relation to the airport safety area and adjacent terrain “contributed to a significant extent to the severity of the accident
and complicated the fire and rescue work.
More generally, and in respect of the consequences of an airworthiness deficiency which it was considered did not inevitable lead to a fatal runway excursion, the Investigation considered that:
- reverted rubber aquaplaning will not occur, or will be significantly reduced, on grooved runways.
- RFFS access to potential crash sites needs more attention in future assessments of safety areas and unobstructed areas in the immediate vicinity of Norwegian airports.
- Runway excursions (by this aircraft type) “could be prevented by a better understanding of the system influence to each other related to failures of the lift spoilers and the effect that it has on the aircraft stopping distance.
Two Safety Recommendations were made as a result of the Investigation
- that CAA Norway, in its system for technical and operational approval of airports, revise its practice for handling nonconformities with a view to establishing requirements for risk compensation. [SL No. 2012/02T]
- that EASA in cooperation with BAE Systems makes operators of the BAe 146 aware of the problem associated with inoperative lift spoilers. This should be included in both theoretical and practical training. [SL No. 2012/03T]
The Final Report of the Investigation SL 2012/04 was published on 18 April 2012.