British European Airways Flight 548
Flight deck of a BEA Trident.
|Date||18 June 1972|
|Summary||Deep stall – aircraft misconfiguration caused by pilot error|
|Aircraft type||Hawker Siddeley Trident 1C|
|Operator||British European Airways|
|Flight origin||London Heathrow Airport|
British European Airways Flight 548 was a scheduled passenger flight from London Heathrow to Brussels on 18 June 1972 which crashed soon after take-off, killing all 118 people on board. The accident became known as the Staines disaster and remained the deadliest air disaster in Britain until the Pan Am Flight 103 crash at Lockerbie, Scotland, in 1988.
The Hawker Siddeley Trident suffered a deep stall in the third minute of the flight and crashed near the town of Staines, narrowly missing a busy main road. The ensuing inquest principally blamed the captain for failing to maintain airspeed and configure the high-lift devices correctly. It cited the captain's heart condition and the limited experience of the co-pilot, while also noting an unspecified "technical problem" that they apparently resolved while still on the runway.
The crash took place against the background of a pilots' strike that had caused bad feelings between crew members. The strike had also disrupted services, causing Flight 548 to be loaded with the maximum weight allowable.
Recommendations from the inquiry led to the mandatory installation of cockpit voice recorders in British-registered airliners. Another recommendation was for greater caution before allowing off-duty crew members to occupy flight deck seats.
Two of the pilots' unions protested at the conduct of the inquiry, which was likened to a 'lawyers' picnic'.
- 1 Industrial relations background
- 2 Operational background
- 3 Accident synopsis
- 4 Investigation and public inquiry
- 5 Victims
- 6 Memorials
- 7 Dramatisation
- 8 See also
- 9 References
- 10 External links
Industrial relations background
The International Federation of Air Line Pilots' Associations (IFALPA) had declared Monday 19 June 1972 (the day after the accident) as a worldwide protest strike 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 BEA whether they wanted to strike. Because of the impending strike, travellers had amended their plans to avoid disruption, and as a result flight BE 548 was full, despite Sunday being traditionally a day of light travel.
BALPA was also in 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 22 BEA Trident co-pilots known as supervisory first officers (SFOs) were already on strike, citing their low status and high workload. To help train newly qualified co-pilots, SFOs were told to occupy only the third flight deck seat of the Trident as a "P3", operating the aircraft's systems and helping the captain (known as "P1" on the BEA Trident fleet) and the co-pilot ("P2") who handled the aircraft. In other airlines and aircraft, the job of SFO/P3s was usually performed by flight engineers. As a result of being limited to the P3 role, BEA Trident SFOs/P3s were denied experience of aircraft handling, which led to loss of pay, which they resented. In addition, their status led to a regular anomaly: experienced SFO/P3s could only assist while less-experienced co-pilots actually flew the aircraft.
Captain Key's outburst
Tensions and hazards came to a head shortly before the accident. On Thursday 15 June, a captain complained that his inexperienced co-pilot "would be useless in an emergency". Upset, the co-pilot committed a serious error on departure from Heathrow. 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".
An hour and a half before the departure of B 548, its rostered captain, Stanley Key, was in a quarrel in the crew room at Heathrow's Queen's Building with a first officer named Flavell. The subject was the threatened strike, which Flavell supported and Key opposed. Both of Key's flight deck crew on BE548 witnessed the altercation, and another bystander described Key's outburst as "the most violent argument he had ever heard". Shortly afterwards 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 Papa India.[nb 1] The graffiti on Papa India's flight engineers' desk was analysed by a handwriting expert to determine who had written it, but this could not be determined and the public inquiry dismissed it as irrelevant.[nb 2]
The aircraft operating Flight BE 548 was a Hawker Siddeley Trident Series 1 short- to medium-range three-engined airliner. This particular Trident was one of twenty-four de Havilland DH.121s ordered by BEA in 1959, and with the constructor's number 2109 it was registered to the corporation as G-ARPI in 1961. By the time of the aircraft's first flight on 14 April 1964 the company had become Hawker Siddeley Aviation, and Papa India was delivered to BEA on 2 May 1964. The Trident I was equipped with three interconnected high-lift devices on each wing leading edge – two droops outboard and a Krueger flap on the section closest to the fuselage.
While technically advanced, the Trident (and other aircraft with a T-tail arrangement) had potentially dangerous stalling characteristics. If its airspeed was insufficient, and particularly if its high-lift devices were not extended at the low speeds typical of climbing away after take-off or of approaching to land, it could enter a deep stall (or "superstall") condition, in which the tail control surfaces become ineffective (as they are in the turbulence zone of the stalled main wing) from which recovery was practically impossible.
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: "After a critical angle of attack was reached, the Trident began to sink tail-down in a deep stall." Eventually it entered a flat spin, and a crash "looked inevitable", but luck saved the test crew.[nb 3] 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.
These systems were the subject of "one of the most comprehensive stall programmes on record", involving some 3,500 stalls being performed by Hawker Siddeley before the matter "was squared off to the satisfaction of ... the ARB" (Air Registration Board). The stall warning and recovery systems tended to over-react: of ten activations between the Trident entering service and June 1972, only half were genuine, although there had been no false in-flight activations [clarification needed]. 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 the airline after the accident showed that this was not the case; 21 captains stated that they had witnessed their co-pilots react correctly to any stall warnings.
The aircraft type's potential to enter a deep stall was highlighted in the crash of Trident 1C G-ARPY on 3 June 1966 near Felthorpe in Norfolk during a test flight, with the loss of all four pilots on board. In this accident the crew had deliberately switched off the stick shaker and stick pusher to perform their stall tests, 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 NASA), brought to light two earlier 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.
Orly (Paris) incident
In December 1968 the captain of a Trident 1C departing Paris-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 afterwards 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 fortunately 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.
In a further 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.[nb 4] The aircraft's automatic systems sensed the loss of airspeed and lift and issued two stall warnings. Since the crew did not initially detect anything amiss, they disabled the automatic system. While doing so, the first officer noted and immediately remedied the problem by re-extending the retracted slats, and the flight continued normally.
Investigators into the event found no mechanical malfunction that could have caused the premature leading edge device retraction, and stated that the aircraft had "just about managed to stay flying". A possible design fault in the high-lift control interlocks came under suspicion, although this was discounted during the investigation into the crash of Papa India. The event became known as the "Naples Incident" or the "Foxtrot Hotel Incident" (after the registration of the aircraft concerned) at BEA and was examined during the accident inquiry. The forward fuselage of this aircraft is preserved and on public display at the de Havilland Aircraft Heritage Centre, London Colney.
Previous ground accident involving G-ARPI
An accident affecting the particular Trident operating as BE 548 had occurred on 3 July 1968. Due to a control failure an Airspeed Ambassador freight aircraft, G-AMAD, deviated from the runway on landing at Heathrow and struck G-ARPI and its neighbouring sister aircraft, G-ARPT, while they were parked unoccupied near Terminal 1, resulting in six fatalities from the freighter's eight occupants. G-ARPT had been cut in two and was damaged beyond economic repair, but G-ARPI which had lost its tail fin was repaired at a cost of £750,000 and had performed satisfactorily thereafter.[nb 5]
Note: All timings in Greenwich Mean Time (GMT) from the official accident report.
The flight crew boarded BE 548 (call sign Bealine 548) at 15:20 to prepare for a 15:45 departure. The crew comprised Captain Stanley Key as P1, Second Officer Jeremy Keighley as P2 and Second Officer Simon Ticehurst as P3. Captain Key was 51 and had 15,000 flying hours experience, including 4,000 on Tridents. Keighley was 22 and had joined line flying a month and a half earlier, with 29 hours as P2. Ticehurst was 24 and had over 1,400 hours, including 750 hours on Tridents.
Among the passengers were 29 Americans, 29 Belgians, 28 Britons, 12 Irish, four South Africans and three Canadians. There was also one passenger from each of French West Africa, India, Jamaica, Latin America, Nigeria and Thailand. The passengers included between 25 and 30 women and several children.
At 15:36 flight dispatcher J Coleman presented the load sheet to Key whose request for engine start clearance was granted three minutes later. As the doors were about to close, Coleman asked Key to accommodate a BEA flight crew that had to collect a Merchantman aircraft from Brussels. The additional weight of the three crew members necessitated the removal of a quantity of mail and freight from the Trident to ensure its total weight (less fuel) did not exceed the permitted maximum of 41,730 kg. This was exceeded by 24 kg, but as there had been considerable fuel burnoff between startup and takeoff, the total aircraft weight (including fuel) was within the maximum permitted take-off weight.
The "dead-heading" crew was led by Captain John Collins, an experienced former Trident First Officer, who was allocated the observer's seat on the flight deck. One seat, occupied by a baby, was freed by the mother holding it in her arms.
The doors closed at 15:58 and at 16:00 Key requested pushback. At 16:03 BE 548 was cleared to taxi to the holding point adjacent to the start of Runway 27 Right. During taxi, at 16:06 the flight received its departure route clearance: a routing known as the "Dover One Standard Instrument Departure". This Standard Instrument Departure involved taking-off to the west over the Instrument Landing System localiser and middle marker beacon of the reciprocal Runway 09 Left, turning left to intercept the 145° bearing to the Epsom Non-Directional Beacon (NDB) (to be passed at 3,000 feet (910 m) or more), and then proceeding to Dover. Key advised the tower that he was ready for take-off and was cleared to do so. He subsequently reported an unspecified technical problem and remained at the holding point for two minutes to resolve it.
At 16:08 Key again requested and received take-off clearance. A cross wind was blowing from 210° at 17 knots (31 km/h). Conditions were turbulent, with driving rain and a low cloud base of 1,000 feet (300 m); broken cloud was also reported at 600 feet (180 m).[nb 6] At 16:08:30 BE 548 began its take-off run, which lasted 44 seconds, the aircraft leaving the ground at an indicated airspeed (IAS) of 145 knots (269 km/h). The safe climb speed (V2) of 152 knots (282 km/h) was reached quickly, and the undercarriage was retracted. After 19 seconds in the air the autopilot was engaged at 355 feet (108 m) and 170 knots (310 km/h); the autopilot's airspeed lock was engaged even though the actual required initial climb speed was 177 knots (328 km/h).
At 16:09:44 (74 seconds after the start of the take-off run), passing 690 feet (210 m), Key began the turn towards the Epsom NDB and reported that he was climbing as cleared and the flight entered cloud. At 16:10 (90 seconds), Key commenced a standard noise abatement procedure which involved reducing engine power. As part of this, at 16:10:03 (93 seconds) he retracted the flaps from their take-off setting of 20°. Shortly afterwards, BE 548 reported passing 1,500 feet (460 m) above ground level and was re-cleared to climb to 6,000 feet (1,800 m) above sea level. During the turn, the airspeed decreased to 157 knots (291 km/h), 20 knots (37 km/h) below the target speed.
At 16:10:24 (114 seconds), the leading edge devices were selected to be retracted at a height above the ground of 1,770 feet (540 m) and a speed of 162 knots (300 km/h), 63 knots (117 km/h) below the safe droop-retraction speed of 225 knots (417 km/h). One second afterwards, visual and audible warnings of a stall activated on the flight deck, followed at 16:10:26 hrs (116 seconds) by a stick shake and at 16:10:27hrs (117 seconds) by a stick push which disconnected the autopilot, in turn activating a loud autopilot disconnect warning horn that continued to sound for the remainder of the flight. Key levelled the wings but held the aircraft's nose up, which kept the angle of attack high, further approaching a stall.
By 16:10:32 (122 seconds), the leading edge devices had stowed fully into the wing. The speed was 177 knots (328 km/h), and height above the ground was 1,560 feet (480 m), with the aircraft still held into its usual climb attitude. Key continued to hold the nose-up attitude when there was a second stick shake and stick push in the following two seconds. A third stick push followed 127 seconds into the flight but no recovery was attempted. One second later, the stall warning and recovery system was over-ridden by a flight crew member.
At 16:10:39 (129 seconds), the aircraft had descended to 1,275 feet (389 m) and accelerated to 193 knots (357 km/h) as a result of the stall recovery system having pitched the aircraft's nose down to increase airspeed. G-ARPI was in a 16° banked turn to the right, still on course to intercept its assigned route. Key pulled the nose up once more to reduce airspeed slightly, to the normal 'droops extended' climb speed of 177 knots (328 km/h), but this further stalled the aircraft.
At 16:10:43 (133 seconds), the Trident entered a deep stall. It was descending through 1,200 feet (370 m), its nose was pitched up by 31°, and its airspeed had fallen below the minimum indication of 54 knots (100 km/h). At 16:10:55 (145 seconds) and 1,000 feet (300 m), the Trident was descending at 4,500 feet per minute (23 m/s). Impact with the ground came at 16:11 precisely, 150 seconds after brake release.
The aircraft just cleared high-tension overhead power lines and came to rest on a narrow strip of land surrounded by tall trees immediately south of the A30 road, and a short distance south of the King George VI Reservoir near the town of Staines-upon-Thames. There was no fire on impact, but one broke out during the rescue effort when cutting apparatus was used.
Eyewitnesses and rescue operations
We were out with the dog and I looked up and saw the plane. It was just coming out of the mist when the engines stalled and it seemed it glided down. It was just like a dream. The plane just fell out of the sky. We just about saw it hit the ground ... because it was right in a clump of trees. When it did hit the ground the front bit hit first and the back bit was just blown away.—Trevor Burke, Mayday
Air traffic controllers had not noticed the disappearance from radar and emergency services only became aware of the accident after 15 minutes and did not know the circumstances for nearly an hour. First on the scene was a nurse living nearby, who had been alerted by the boys, and an ambulance crew that happened to be driving past. A male passenger who had survived the accident was discovered in the aircraft cabin, but died without recovering consciousness on arrival at Ashford Hospital. A young girl was also found alive but died at the scene; there were no other survivors. Altogether, 30 ambulances and 25 fire engines attended the accident.
Drivers formed heavy traffic jams and were described by Minister of Aerospace Michael Heseltine on BBC Television that evening as "ghouls, unfortunate ghouls". Reports that the public impeded rescue services were dismissed during the inquiry. In addition, some witnesses claimed the traffic jams were the result of the recovery and rescue, during which the police closed the A30 road.
A BEA captain, Eric Pritchard, arrived soon after the bodies had been removed; he noted the condition of the wreckage and drew conclusions:
The aircraft had impacted in a high nose up attitude. The No. 2 engine had dug a considerable crater. The tail section was almost if not completely separated from the rest of the airframe. There was little evidence of any forward movement, in fact, the complete aircraft looked intact though distorted and broken, mainly the fuselage. Both wings suffered not much visible damage. I noticed that the droops and flaps were retracted.—Eric Pritchard, Mayday"
The accident became known as the Staines disaster, the worst air disaster in Britain until the Pan Am Flight 103 crash at Lockerbie, Scotland in 1988. The crash was the first in the United Kingdom involving the loss of more than 100 lives.
Investigation and public inquiry
On Monday 19 June 1972 Michael Heseltine announced to the British Parliament that he had directed a Court of Inquiry, an ad hoc tribunal popularly called a "public inquiry", to investigate and report on the accident. Public inquiries bypassed the usual British practice whereby the Accidents Investigation Branch (AIB) investigated and reported on air crashes, and were held only in cases of acute public interest. On 14 July, the High Court Judge Sir Geoffrey Lane was appointed to preside over the inquiry as Commissioner.
The British aviation community was wary of public inquiries for several reasons. In such inquiries, AIB inspectors were on an equal footing with all other parties, and the ultimate reports were not drafted by them, but by the Commissioner and his or her Assessors. Proceedings were often adversarial, with counsel for victims' families regularly attempting to secure positions for future litigation, and deadlines were frequently imposed on investigators. Pressure of work caused by the Lane Inquiry was blamed for the death of a senior AIB inspector who committed suicide during the inquiry.
AIB investigation and coroner's inquest
The aircraft's two flight data recorders were removed for immediate examination, and investigations at the site of the accident were completed within a week. The wreckage of Papa India was then removed to a hangar at the Royal Aircraft Establishment in Farnborough, Hampshire, for partial re-assembly aimed at checking the integrity of its flight control systems. An inquest was held into the 118 deaths, opening on 27 June 1972.
The pathologist stated that Captain Key had a pre-existing heart condition, atherosclerosis, and had suffered a potentially distressing arterial event caused by raised blood pressure typical of stress. (This event was popularly interpreted by the public as a heart attack.) It had taken place "not more than two hours before the death and not less than about a minute" according to the pathologist's opinion given as evidence during the public inquiry. In other words, Key could have suffered it at any time between the row in the crewroom and 90 seconds after the start of the take-off run or the instant of commencing noise abatement procedures. The pathologist could not specify the degree of discomfort or incapacitation which Key might have felt. The Captain's medical state continued to be the subject of "conflicting views of medical experts" throughout the inquiry and beyond.
The public inquiry, known as the "Lane Inquiry", opened at the Piccadilly Hotel in London on 20 November 1972, and continued for 37 business days until 25 January 1973 despite expectations that it would end sooner. It was opened by Geoffrey Wilkinson of the AIB with a description of the accident, and counsel for the relatives of the crew members and passengers then presented the results of their private investigations. In particular, Lee Kreindler of the New York City Bar presented claims and arguments which were considered tendentious and inadmissible by pilots and press reporters. They involved hypotheses about the mental state of Captain Key, conjecture about his physical state (Kreindler highlighted disagreements between US and British cardiologists) and allegations about BEA management. The allegations were delivered using tactics considered as "bordering on the unethical". The inquiry also conducted field inspections, flew in real Tridents and "flew" the BEA Trident simulator as well as observing the Hawker Siddeley Trident control systems rig. Its members visited the reassembled wreckage of G-ARPI at Farnborough and were followed by the press throughout their movements. The bare facts being more-or-less uncovered soon after the event, the inquiry was frustrated by the absence on the accident aircraft of a cockpit voice recorder.[nb 7]
The stall warning and stall recovery systems were at the centre of the inquiry, which examined in some detail their operation and why the flight crew might have over-ridden them. A three-way air pressure valve (part of the stall recovery system) was found to have been one-sixth of a turn out of position, and the locking wire which secured it was missing. Calculations carried out by Hawker Siddeley determined that if the valve was in this position during the flight then the reduction in engine power for the noise abatement procedure may well have activated the warning light that indicated low air pressure in the system. The failure indications might have appeared just prior to take-off and could have accounted for the two-minute delay at the end of the runway. A captain who had flown Papa India on the morning of the accident flight noted no technical problems, and the public inquiry found that the position of the valve had no significant effect on the system.
Findings and recommendations
The Lane Report was published on 14 April 1973. Speaking in the House of Commons Minister for Aerospace and Shipping Michael Heseltine paid tribute to the work done by Mr Justice Lane, Sir Morien Morgan and Captain Jessop for the work they had carried out during the inquiry into the accident.
The inquiry's findings as to the main causes of the accident, were that:
- The captain failed to maintain the recommended airspeed.
- The leading edge devices were retracted prematurely.
- The crew failed to monitor airspeed and aircraft configuration.
- The crew failed to recognise the reasons for the stall warnings and stall recovery system operation.
- The crew wrongly disabled the stall recovery system.
Underlying causes of the accident were also identified:
- Captain Key was suffering from a heart condition.
- The presence of Captain Collins on the flight deck may have been a distraction.
- There was a lack of crew training on how to manage pilot incapacitation.
- The low flying experience level of Second Officer Keighley.
- Apparent crew unawareness on the effects of an aircraft configuration change.
- Unawareness of the crew regarding the stall protection systems and the cause of the event.
- The absence of a baulk mechanism to prevent droop retraction at too low an airspeed.
Recommendations included an urgent call for cockpit voice recorders and for closer co-operation between the Civil Aviation Authority and British airlines. Though the report covered the state of industrial relations at BEA, no mention was made of it in its conclusions, despite the feelings of observers that it intruded directly and comprehensively onto the flight deck of the stricken aircraft. BEA ceased to exist as a separate entity in 1974, when it and the British Overseas Airways Corporation merged to form British Airways. A recommendation of the report that all British-registered civil passenger-carrying aircraft of more than 27,000 kg (60,000 lb) all-up weight should be equipped with cockpit voice recorders resulted in their fitting becoming mandatory on larger British-registered airliners from 1973.
One issue treated as secondary at the inquiry was the presence on the flight deck observer's seat of Captain Collins. The Lane report recommended greater caution in allowing off-duty flight crew members to occupy flight deck seats, and aired speculation that Collins might have been distracting his colleagues. Sources close to the events of the time suggest that Collins played an altogether more positive role by attempting to lower the leading edge devices in the final seconds of the flight.[nb 8]
There were protests at the conduct of the inquiry by BALPA (which likened it to "a lawyers' picnic"), and by the Guild of Air Pilots and Air Navigators which condemned the rules of evidence adopted and the adversarial nature of the proceedings. Observers also pointed to an unduly favourable disposition by the inquiry to Hawker Siddeley, manufacturer of the Trident, and to the makers of the aircraft's systems. Debate about the inquiry continued throughout 1973 and beyond.
Among those killed were 12 senior businessmen from Ireland, including the head of the Confederation of Irish Industry, en route to Brussels for meetings preparatory to Ireland's accession to the European Economic Community. A referendum approving Ireland's entry had been passed in May.
A group of 16 doctors and senior staff from the Royal London Homeopathic Hospital were also on board the flight, and a memorial bench to them can be found close to Great Ormond Street Hospital in Queen Square.
Coming back from the JCI European Conference in Edinburgh, there was a group of seven members of JCI Belgium, together with two partners who were killed. The JCI Staines Foundation was established, supporting the families and children of the members that never reached Brussels.
The top two scientists of Raychem Corporation, a Fortune 500 company headquartered in a Menlo Park, California were also on board. They had been visiting the company's offices in Swindon.
Two memorials to the crew and passengers were dedicated on 18 June 2004 in Staines-upon-Thames.
A tree planted in memory of the Belgian citizens who died in the crash is situated in the Square Frère-Orban, Brussels.
The story of the accident was featured on the thirteenth season of Canadian National Geographic Channel show Mayday in an episode entitled "Britain's Worst Air Crash" (known as Air Emergency in the US, Fight to the Death in Canada, Mayday in Ireland and Air Crash Investigation in the UK and the rest of world). Also featured in an episode of Air Crash Confidential produced by World Media Rights; made at the FAST Museum, Farnborough, UK using the cockpit of Trident three G-AWZI.
- Similar accidents
- The aircraft is commonly referred to as Papa India from the phonetic spelling of the last two letters of its civil registration (G-ARPI).
- Sections of the analysed graffiti were said to resemble the handwriting of Simon Ticehurst (Second Officer/P3) but the inquiry found that none of the graffiti had been written by crew members on BE548 on the day of the accident (Ticehurst had similar views to those of Key).
- A wing dropped during the stall, when corrected with rudder the other wing dropped, and the aircraft continued rolling left and right until the nose pitched down and the crew were able to recover to normal flight.
- The Trident 1 featured drooping leading edge devices, the Trident 2 employed extending slats. Their aerodynamic effect was similar, and both devices were controlled by the same lever on the flight deck. Crews often referred to both types as 'droops'.
- This accident is included as it is mentioned in references but had no bearing on BE 548.
- The official report notes that the crew would have been without any visual reference at "crucial times" during the flight.
- A full list of inquiry board members, counsel and witnesses is given at Appendix A to the official accident report.
- Bartelski's (2001) source, Eric Pritchard, a Trident captain who happened to be the first airman at the accident site, recalls that a fireman had stated that Collins was lying across the centre pedestal and noted himself that his earphones had fallen into the right hand side footwell of the flight deck, diagonally across from the observer's seat, as may be expected if he had attempted to intervene as a last resort.
- Stewart 2001, p. 91.
- Bartelski 2001, p. 184.
- Bartelski 2001, ch. 6.
- AIB Report 4/73, pp. 23–24.
- Stewart 2001, p. 92.
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- AIB Report 4/73, p. 22.
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- AIB Report 4/73, pp. 21–22.
- AIB Report 4/73, p. 21.
- "B.E.A. Sign £29M. Jet Contract – First Delivery of DH 121 in 1963" (News). The Times (London). Thursday, 13 August 1959. (54538), col A, p. 5.
- "CA Form 113 (Nationality and Registration Marks G-ARPI)". Civil Aviation Authority. Retrieved 4 August 2010.
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- [Staff author] 29 June 1972. "Inquiry briefing" Flight International, p. 932a. Retrieved: 30 December 2009.
- AIB Report 4/73, p. 10.
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- AIB Report 4/73, p. 52.
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- 1971 | 0115 | Flight Archive. Flightglobal.com (21 January 1971). Retrieved on 17 December 2013.
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- AIB Report 4/73, pp. 36–37.
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- Brookes 1996, p. 142.
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- Bartelski 2001, p. 207.
- Bartelski 2001, p. 199.
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- AIB Report 4/73, Cover note from Sir Geoffrey Lane to The Rt Honourable Peter Walker, Secretary of State for Trade and Industry (un-numbered fifth page of PDF document).
- [Staff author] 28 December 1972. "Trident inquiry extended" FLIGHT International, p. 921. Retrieved: 29 December 2009.
- Bartelski 2001, p. 196.
- Bartelski 2001, p. 197.
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- Bartelski 2001, p. 195.
- AIB Report 4/73 – Appendix A, p. 68.
- AIB Report 4/73, pp. 18–19.
- "Trident Aircraft Accident (Report)". House of Commons debates 856. Hansard. 9 May 1973. Retrieved 17 August 2010. "cc489-97"
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- AIB Report 4/73, p. 56.
- AIB Report 4/73, p. 59.
- United Kingdom Civil Aviation Authority (1 May 1974), Specification No. 10 – Flight Data Recorder Systems – Issue 2, TSO, ISBN 1 904862 71 3, retrieved 30 December 2009
- Bartelski 2001, p. 204.
- Letter from Lord Trefgarne, House of Lords FLIGHT International 23 August 1973, Letters, p. 779. Retrieved: 13 January 2010.
- Bartelski 2001, p. 194.
- Carswell, Simon (24 June 2007). "Call for memorial to businessmen killed in air crash". The Sunday Business Post. Retrieved 8 December 2010.
- Sue Young (31 December 2008). "John Robertson Raeside 1926 – 1972." Biographies of Homeopaths. Retrieved 9 July 2011.
- "Prayers said for victims of 1972 Staines air disaster." BBC. 18 June 2011. Retrieved 9 July 2011.
- "Memorial for plane crash victims." BBC. Retrieved 26 October 2008.
- Bartelski, Jan. Disasters in the Air: Mysterious Air Accidents Explained, Shrewsbury, Shropshire. Airlife Publishing Ltd, 2001. ISBN 1-84037-204-4
- Brookes, Andrew. Disaster in the air. Shepperton, Surrey. Ian Allan Ltd. 1996. ISBN 0-7110-2037-X
- Civil Aircraft Accident Report 4/73: Trident I G-ARPI: Report of the Public Inquiry into the Causes and Circumstances of the Accident near Staines on 18 June 1972. Accident Investigation Branch, Department of Trade and Industry. HMSO, London, 1973.
- Civil Aircraft Accident Report 4/73: Trident I G-ARPI: Report of the Public Inquiry into the Causes and Circumstances of the Accident near Staines on 18 June 1972 – Appendix A Accident Investigation Branch, Department of Trade and Industry. HMSO, London, 1973.
- Ellis, Ken. Wrecks and Relics – 19th Edition, Hinckley, Leicestershire. Midland Publishing, 2004. ISBN 1-85780-183-0
- Faith, Nicholas. Black Box. London, Macmillan Publishers Ltd. 1997. ISBN 0-7522-1084-X
- Gero, David. Aviation Disasters. Yeovil, Somerset. Patrick Stephens Ltd (Haynes Publishing). 1997 ISBN 1-85260-526-X
- Job, Macarthur. Air Disaster Volume 1. Weston Creek, ACT, Aerospace Publications Pty Ltd. 1994 ISBN 1-875671-11-0
- Roach, John and Eastwood, Tony. Jet Airliner Production List, West Drayton, England, The Aviation Hobby Shop, 1992. ISBN 0-907178-43-X
- Stewart, Stanley. Air Disasters London, Ian Allan Publishing, 2001. ISBN 0-7110-1585-6
- Image of Papa India prior to the accident
- List of Trident accidents including G-ARPY and G-ARPI
- Images of the crash site of G-ARPY (the 'Felthorpe accident')
- Captain Stanley Key pictured (bottom right) at a BALPA party on 7 December 1955 talking to John Profumo, in a 1955 Flight news item
- "Inquiry Briefing" a 1972 Flight article
- "Trident Inquiry – Tests and Procedures" a 1972 Flight article
- "Trident Disaster Analysis Begins" a 1972 Flight article