British European Airways Flight 548 was a scheduled passenger flight from London Heathrow to Brussels that crashed near Staines, England, United Kingdom, shortly after take-off on 18 June 1972, killing all 118 people on board. The accident became known as the Staines air disaster. , it remains the deadliest air accident (as opposed to terrorist incidents) to have occurred in the UK and was the deadliest air accident involving a Hawker Siddeley Trident.
Initially, there were two survivors of the accident; a man, who was discovered in the remains of the aircraft cabin, and a young woman, but both later died of their injuries.
The aircraft had entered a deep stall in the third minute of its flight and had then descended steeply until it crashed into the ground, narrowly missing a busy main road. The public inquiry principally blamed the captain for failing to maintain airspeed and configure the high-lift devices correctly. It also cited the captain's undiagnosed heart condition and the limited experience of the co-pilot while noting an unspecified "technical problem" that the crew apparently resolved before take-off.
The crash took place against the background of an impending pilots' strike that had strained relations between crew members. The strike had also disrupted services, causing Flight 548 to be loaded to the maximum weight allowable. Recommendations from the inquiry led to the mandatory installation of cockpit voice recorders (CVR) in British-registered airliners. Another recommendation was for greater caution before allowing off-duty crew members to occupy flight deck seats. Some observers felt that the inquiry was unduly biased in favour of the aircraft's manufacturers.
Industrial relations background
On Monday 19 June 1972, the day following the accident, the International Federation of Air Line Pilots' Associations (IFALPA) had declared, as a worldwide protest, a strike action against aircraft hijacking, which had become commonplace in the early 1970s. Support was expected, but the British Air Line Pilots Association (BALPA) organised a postal ballot to ask members at British European Airways (BEA) whether they wanted to join the strike. Because of the impending strike, travellers had amended their plans to avoid disruption, and as a result Flight 548 was full despite Sunday being traditionally a day of light travel.
BALPA was also in an industrial dispute with BEA over pay and conditions. The dispute was controversial, those in favour being mainly younger pilots and those against mostly older. A group of twenty-two BEA Trident co-pilots known as supervisory first officers (SFOs) were already on strike, citing their low status and high workload. The mistake was noted and remedied by the SFO, who related the event to colleagues as an example of avoidable danger. This became known among BEA pilots as the "Dublin Incident." Shortly afterward, Key apologised to Flavell and the matter seemed closed.
Key's anti-strike views had won enemies, and graffiti against him had appeared on the flight decks of BEA Tridents, including the incident aircraft, G-ARPI (Papa India). The graffiti on Papa Indias flight engineers' desk was analysed by a handwriting expert to identify who had written it, but this could not be determined. The public inquiry found that none of the graffiti had been written by crew members on Flight 548 on the day of the accident.
Operational background
The aircraft operating Flight 548 was a Hawker Siddeley Trident Series 1 short- to medium-range three-engined airliner. This particular Trident (s/n 2109) was one of twenty-four de Havilland D.H.121s (the name "Trident" was not introduced until September 1960) ordered by BEA in 1959 and was registered to the corporation in 1961 as
The danger first came to light in a near-crash during a 1962 test flight, when de Havilland pilots Peter Bugge and Ron Clear were testing the Trident's stalling characteristics by pitching its nose progressively higher, thus reducing its airspeed. The Trident entered a deep stall after a critical angle of attack was reached. Eventually, it entered a flat spin and appeared to be about to crash, but a wing dropped during the stall, and when corrected with rudder the other wing dropped. The aircraft continued rolling left and right until the nose pitched down and the crew were able to recover to normal flight. The incident resulted in the Trident being fitted with an automatic stall warning system known as a "stick shaker" and a stall recovery system known as a "stick pusher," which automatically pitched the aircraft down to build up speed if the crew failed to respond to the warning. The stall warning and recovery systems tended to over-react: When BEA Trident pilots were questioned informally by one captain, over half of the pilots said that they would disable the protection systems on activation rather than let them recover the aircraft to a safe attitude. Random checks carried out by BEA after the accident showed that this was not the case; twenty-one captains stated that they had witnessed their co-pilots react correctly to any stall warnings.
Felthorpe accident
The Trident's potential to enter a deep stall was highlighted in the crash of Trident 1C G-ARPY on 3 June 1966 near Felthorpe, Norfolk, during a test flight, with the loss of all four pilots on board. In this accident, the crew had deliberately switched off both the stick shaker and stick pusher as required by the stall test schedule, and the probable cause was determined to be the crew's failure to take timely positive recovery action to counter an impending stall. The Confidential Human Factors Incident Reporting Programme (CHIRP), an experimental, voluntary, anonymous and informal system of reporting hazardous air events introduced within BEA in the late 1960s (and later adopted by the Civil Aviation Authority and the Federal Aviation Administration), brought to light two near-accidents, the "Orly" and "Naples" incidents: these involved flight crew error in the first case and suspicion of the Trident's control layout in the second case.
Orly (Paris) incident
In December 1968, the captain of a Trident 1C departing Orly Airport for London tried to improve climb performance by retracting the flaps shortly after take-off. This was a non-standard procedure, and shortly afterward, he also retracted the leading-edge droops. This configuration of high-lift devices at a low airspeed would have resulted in a deep stall, but the co-pilot noticed the error, increased airspeed and re-extended the droops, and the flight continued normally. The event became known as the "Paris Incident" or the "Orly Incident" among BEA staff.
Naples incident
thumb|right|Passenger cabin of Trident 2E, G-AVFH|alt=The passenger cabin of an airliner with orange seats and blue carpeting, the cabin is illuminated by daylight from the windows.
In the second near-accident, a Trident 2E (G-AVFH) climbing away from London Heathrow for Naples in May 1970 experienced what was claimed by its flight crew to have been a spontaneous uncommanded retraction of the leading-edge slats which was initially unnoticed by any of them.