Inexperience “The Trident Tragedy 1972”

“The Trident aircraft was crewed by three pilots with the captain (P1) in the left-hand seat, the co-pilot (P2) in the right-hand seat, and another co-pilot, in the position of the third pilot (P3), seated behind the other two just aft of the centre console. Under normal operating circumstances the P1, and whoever occupied the P2 seat, would share clearly defined aircraft handling roles and co-pilot tasks, at the captain’s discretion, while duties of the P3 included operation and monitoring of systems, completion and checking of paper-work, and monitoring of flight progress. P2 and P3 would also alternate duties by changing seats as agreed with the more senior pilot normally taking precedence. Whilst under training as P2 or P3, the recruits were supervised by a training captain in P1 seat, with an addition during P3 training of a supervisory first officer sitting in the jump seat, an extra fold-away seat fitted on all flight decks for such contingencies. During such P3 training duties, an experienced co-pilot occupied the P2 position. The system was tried and tested and produced competent, well qualified pilots.

In previous years a large recruiting campaign had been conducted by British airlines, and BEA in particular was still active in processing its young pilots through basic training. After completing the commercial pilot’s license and instrument rating at air training school, recruits joining BEA underwent an intensive course of instruction and training on the aircraft to which they were assigned. Ground school, simulator and base flying programs were undertaken and all had to be completed satisfactorily for license requirements. Further training and experience was then gained ‘down line’, i.e. on BEA’s normal commercial services, under strict supervision of suitably qualified flight personnel, before recruits were deemed competent to operate unsupervised.

BEA and the British Airline Pilots’ Association (BALPA) had for some time been at odds over a large number of issues which centred on pay and conditions. The dispute had not only created a certain amount of acrimony between the company and its flight crew but had also divided the pilot community. Many pilots were vehemently opposed to industrial action while others strongly favoured a call to strike. One pilot group of 22 supervisory first officers had already withdrawn their services causing more than a little embarrassment to BEA. Long periods of supervisory duty and poor monetary rewards were not felt to justify the supervisory pilot’s own lack of aircraft handling.

To strike or not to strike, that was the question: or, more correctly, the argument. At London’s Heathrow Airport, the atmosphere in British European Airways (BEA) crew room, like the weather outside, was changing for the worse. Amid the normal bustle of activity in Queen’s Building on a busy Sunday afternoon in June, a large number of pilots had formed an impromptu gathering to discuss their present dispute with the company. Some flight crew present were going to or from work, while others, like Captain Stanley Key, were on standby duty in case of disruption to rostered crews.

One young man present in the crew room that Sunday afternoon on 18 June 1972, was 22-year-old Jeremy Keighley. A keen and enthusiastic pilot, he was one of 36 trainees unable to complete his ‘down line’ experience because of action by the supervisory first officers. He had finished his P2 training and was qualified as co-pilot, but had flown only one sector of line training as P3. Having already completed 16 hr 20 min P3 training on the simulator and 6 hr 45 min base training on the aircraft, it was most frustrating for this young man and his similarly inconvenienced colleagues to be denied the chance of finishing their training. BEA was none too happy about the situation either, and was faced with rostering difficulties as a result. To resolve the dilemma, the airline decided to continue using the trainees for flight crew duties by simply restricting their activities to those for which they were qualified, that is, only as co-pilot sitting in the P2 seat. The anomaly therefore arose that when ‘P2 only’ pilots were rostered to fly unsupervised, they could only occupy the P2 seat, despite being the least experienced of the crew. Thus the junior of the two co-pilots, some with only 250 total flying hours and about a dozen hours simulator and aircraft handling practice on the Trident, would be the pilot required to take control in the event of incapacitation of the captain.

To help maintain continuity of experience a ‘brown line’ system was introduced whereby pilots of less than 12 months “ experience on type” had their names underlined by a brown line and were required to fly with a qualified co-pilot of more than 12 months’ experience. Even so, two junior second officers, one relatively inexperienced and one very inexperienced could be rostered to fly together. Although the young men restricted to P2 duties were acknowledged to be enthusiastic, reliable and well-trained, deep concern was expressed by a large number of captains over their lack of experience which was felt to be far too little for safety. Earlier the same month Aerospace Magazine had published an article written by airline Captain R.C. Leighton-White who supported these views and which stated “to critically monitor and question a captain’s action, the co-pilot must have sufficient training and experience to have the necessary confidence in his own judgement to question a senior pilot’s actions.”

On the previous Thursday (15 June) a certain captain had been rostered with one of the ‘P2 only’ co-pilots to fly to Dublin and back and then on to Nicosia. Aware of the below-average facilities at Nicosia and the possibility of rapid deterioration of the weather, the captain made known his concern and asked for a fully-qualified replacement. His request was denied. Upset by the rebuff and the attitude of management, he vented his feelings on the young co-pilot and more or less told him that he would be useless in an emergency. The outburst had a very upsetting effect on the P2 and did nothing to improve his confidence. On the departure out of London for Dublin, the call to select ‘flaps up’ was made as normal at noise-abatement time, but, still flustered by the incident on the ground, the young man instead selected the flaps fully down. The P3 (Flight Engineer) immediately spotted the action and quickly reversed direction of the flap lever before the movement of the flaps. On the flight deck events happen quickly, and it takes training and experience to function normally in what is potentially a hostile environment. For the new recruit, with as yet undeveloped skills, a great deal of concentration is required to avoid mistakes and the occasional lapse is, perhaps, not surprising. The pressures on these young men, albeit of high calibre, can be very great.

The young P2 involved in the ‘Dublin incident’ happened to share a house with Second Officer Jeremy Keighley who was quickly made aware of the story. The two met amidst the group of pilots gathering in the crew room that Sunday afternoon and Keighley, on standby duty at the same time as Captain Stanley Key, enquired of his friend what Key was like to fly with. The other P2 had no personal experience of working with Stanley Key, although the Captain’s name was well known amongst Trident crew because of a somewhat unfavourable reputation. One of the more puerile aspects of the dispute was the appearance on Trident flight decks of offensive graffiti and Captain Key, known as one strongly opposed to strike action, had been singled out for a certain amount of abuse. Whatever the criticisms, however, his flying skills were generally acknowledged and he was recognized as very competent pilot.

A confidential postal ballot has been arranged by BALPA in an attempt to resolve the dispute and discussion amongst the pilots in the Queen’s Building crew room focused on the outcome. Strong opinions were expressed by both sides as to their preference. As votes were being received at the Association headquarters adjacent to Heathrow, Captain Key, on his own initiative, had been attempting to canvas support against strike action amongst his senior colleagues. He was naturally guarded as to the results of his efforts and was strongly opposed to discussing his actions amongst the pilot community at large. In the rather heated atmosphere at the time, one first officer made the mistake of asking how Key’s endeavours were progressing. The result was instant and furious. Captain Key completely lost his temper and a raging outburst ensued. The first officer was told in no uncertain terms that such matters were none of his business, or anyone else’s, and that the matter had the right to be afforded the same confidentiality as the BALPA ballot. In the eyes of at least one witness it was ‘the most violent argument I have ever heard’, even if it was somewhat one-sided. Captain Key’s anger, however, abated as quickly as it had flared. To his credit he took the first officer in question by the arm and in front of the same group apologized for his behaviour. Thereafter, his manner seemed normal. Second Officer Keighley was also a witness to the spectacle and the effect must have been more than alarming. Like all new recruits he was aware that BEA had its own small number of difficult flight crew members, just like any other airline. Whether Captain Key fell into this category or not is certainly open to conjecture, although he was renowned for a somewhat brusque manner.

He was a man of traditional values, of Royal Air Force and airline service. The new entrants to the company from the air training schools were of a different breed. They had no military training or airline flying experience and were quite alien to Stanley Key. They were of another generation, some thirty years younger. He had little in common with these new entrants and was somewhat suspicious of their abilities. A few, like Jeremy Keighley, were very raw recruits indeed. It would not be unfair to say that Captain Key probably felt uncomfortable in the company of these young men as they did in his. After the incident in the crew room, Keighley’s impression of Key is not known, although the effect could hardly have been reassuring. The effect of the argument on Captain Key, however, was far more sinister.

Captain Key was short in stature and, at 51, seemed to have no more than the usual problem with weight for a man of his age and build. To those who knew him, he presented a ‘picture of robust good health’. He actively pursued his gardening hobby and neither his wife nor family doctor had any reason to suspect anything amiss. However, something was seriously wrong with Captain Key’s health and his condition had been progressively deteriorating over a very long period. As far back as his 20s, he had been suffering from atherosclerosis. The disease had now reached a severe stage and the arteries of his heart had been narrowed in places by some 50-70 %. Unknown even to those close to him, his life expectancy was short.

All flight crew, of course, undergo medical examinations at regular intervals, which for a pilot of Key’s age would be every six months with the addition each year of an electrocardiogram (ECG). This test reveals any heart muscle abnormality but, unfortunately, it rarely shows narrowing of the arteries. As a result, neither of Key’s previous two ECGs, in 1970 and 1971, indicated a problem. It has been argued that a ‘stress ECG’, where the patient is subjected to rigorous exercise before the readings are taken, may have detected the diseased arteries, but such tests were not considered by medical opinion at the time to be sufficiently reliable. Too many ‘false positives’ and ‘false negatives’ resulted. Captain Key’s heart condition could have been ascertained by means of an arteriogram, but the procedure was deemed much too risky for routine examinations. To all intent and purposes, therefore, Key’s regular check-ups proved him to be fit and healthy specimen.

The fatty or fibrous deposit on the walls of Key’s coronary arteries escaped detection and remained a serious health risk. Within the pathologically thickened walls, small blood vessels developed, which, in keeping with the unnatural growth were weak and prone to rupture? During Key’s very angry outburst in the crew room, his blood pressure soared to dangerous levels with damaging results. At this moment, as near can be certain, a delicate blood vessel in the left coronary artery ruptured causing haemorrhage. The resulting pressure from the blood on the arterial wall would, with time, force separation of part of the arterial lining. At that juncture the effect would be ‘anything from slight pain akin to indigestion at one end to nigh death at the other’. It would certainly not be a moment of concentration and alertness.

About one hour after the altercation in the Queen’s Building, a standby crew was ‘tannoyed ‘ for service. The crew rostered to fly the BE 548 to Brussels was delayed on their return to London and others were required to take their place. The crew selected consisted of 51-year-old Captain Stanley Key, unknowingly suffering from a serious heart condition; 22-year-old Second Officer Jeremy Keighley, of little experience and restricted to ‘P2 duties only’, and 24-year-old Second Officer Simon Ticehurst, competent, conscientious, and relatively experienced, but still only a junior officer.

Captain Key had 15,000 flying hours to his credit, with 4,000 hours in command on Tridents. His skill and ability could not be questioned. On proceeding to the aircraft, however, Key would be experiencing a degree of discomfort leading to increasing pain. The effect would be sufficient to distract his train of thought and progressively to affect his reasoning powers. The ultimate tearing of the arterial lining would not be far away, with serious consequences waiting.  If such an event occurred during a critical stage of the flight, control would rest in the hands of a young man who, through no fault of his own, had very little experience. Keighley would doubtless also be feeling ill at ease on the way to the flight, but what apprehensions he felt at the encounter with Key can only be surmised. Report of his progress through basic and advanced training indicated that, when judged by the very high standards demanded, he was somewhat under confident. On the simulator he was found to be ‘slow to react to an emergency’ and that ‘he lacked initiative’. However, a handing-over report the month before had reported him as ‘slower than average and will call for patient, rather than pressure handling’. What kind of handling could Second Officer Keighley expect from Captain Key this day?

Monitoring the flight and the other pilot’s performance would be young Ticehurst, a thoroughly reliable and able pilot. He already had a total of 1,400 hours under his belt, with 750 hours on Tridents and would carefully chaperon their progress. As the three standby pilots mounted the steps of their Trident aircraft, the weather continued to worsen, turning the day into a typical wet British Sunday. In the late afternoon an approaching cold front, now lying some 30 miles to the west, resulted in overcast skies with a cloud base of 1,000 ft, fresh winds from the south west, and rain. Flying conditions were unpleasant and turbulent. The Trident 1 being boarded by the crew, G-ARPI (Papa India) was, as the type name suggests, a three-engined aircraft similar to, although smaller than, the Boeing 727 which it preceded in conception.

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The first Trident 1 flight took place on 9 January 1962, and the first Boeing 727 flight more than one year later on 9 February 1963. The Americans very quickly caught up, however, and delivery flights of the Trident 1 to BEA and Boeing 727 to United Airlines were completed in December and October 1963 respectively. Both types had three engines grouped at the rear with the tail plane placed free of the engines high on the tail fin. The resultant configuration had certain advantages over wing-mounted engine designs, the simplest and most obvious being the ability to install an odd numb of engines. Asymmetric thrust (i.e. one engine failed) problems were also reduced, thus allowing take-offs in low visibility. On wing-mounted engine aircraft, failure of an outboard engine on take-off can result in a pronounced swing because of the large power imbalance. Better visibility is therefore required for pilot guidance in case such an event occurs. The advantages of tail-engined jets, however, are not achieved without penalties. Severe engine failure on a tail mounted design increases the possibility of damage to another engine because of their close proximity, and, with most fuel contained in the wings, fuel pipes running through the fuselage are a potential fire hazard in the event of an accident.

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Leading edge flaps known as droops on the wings. Help in lift.

Trident and Boeing 727 type aircraft also have the potential to ‘deep stall’. As an aircraft slows, to maintain lift, the angle of the wing to the airflow has to be increased by raising the aircraft’s nose. If the speed is allowed to become too slow and the nose-up attitude is excessive, a point is reached at which the smooth airflow over the wing breaks down and most lift is lost. This condition is known as ‘stalling’. With lift lost from the wings, the aircraft flutters flatly from the sky like a falling leaf. Recovery is achieved by forcing the aircraft into a dive using full down elevator and by applying full power until flying speed is once again achieved. The aircraft can then be pulled out of the dive and flown straight and level. Stalling can also occur with an inadvertent change of the wing configuration resulting in lift loss. On modern jets the wings are swept back at a large angle to allow the aircraft to cruise at high speeds by delaying the onset of shock waves as the airflow over the wing approaches the speed of sound. At slow aircraft speeds, however, the lift producing qualities of the wing are poor. High lift producing devices are required to improve lift by increasing the surface area and by altering the camber of wing profile. On the Trident 1 aircraft a combination of Kruger and droop systems were employed at the wing leading edge, with conventional flaps extending at the trailing edge. The droop system, peculiar to the Trident 1 aircraft increased the camber of the wing by quite literally drooping the leading edge of the wing by hydraulic operation. The droops were hinged at the bottom and when extended, moved outwards and downwards from the top, the resultant gap between the wing upper edge and the rear of the droop being closed by a sealing plate. Inboard of the droops, Kruger flaps were hinged along the leading edge and were extended downwards and forwards like a narrow door along the inboard wing length. The droops extended over the larger part of the wing and as such the leading edge droops and Kruger devices were simply referred to as droops.

The Trident was the first British aircraft to be fitted with retractable leading edge high lift producing devices and the system was simple and effective, but not without its problems. The droops and flaps were operated independently by two separate levers situated side by side to the right of the centre console. The lift producing qualities of the droops were considerably greater than the flaps and the danger of inadvertent retraction of the droops instead of the flaps at low speed was readily apparent (aircraft since have a single lever for both leading and trailing edge lifting devices). If the droops are retracted unintentionally at too low a speed and the high lift generated by the devices is lost, the aircraft will instantly be close to stall condition and in imminent danger of falling from the sky. In a stall caused by this change in configuration, re-extension of the droops would be the obvious recovery procedure, although full stall recovery action may also have to be initiated. To prevent inadvertent retraction of the droops instead of the flaps the droop lever was protected by a mechanical guard throughout most of the flap lever range. After selection of flaps up, the droop lever was unguarded. A climb to 3,000 ft, and further acceleration to the minimum ‘droops up’ safety speed of 225 knots,  was then required before droop retraction. During the period of about two minutes the droop lever was unprotected, but since there was no requirement to operate either lever, a speed guard was not considered necessary.

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At a later date the speed guard was introduced. An amber warning light placed forward of the droop lever was arranged to illuminate if the droop lever was out of position: i.e. if the airspeed was too low when retracted or if excessive when extended.

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Deep stalling explained; in a deep stall the elevator also comes in the turbulent airflow and is thus ineffective is ineffective in any recovery action

On more conventional aircraft at the time, approach to the stall was announced by buffeting of the aircraft as air over the wing became turbulent. If no action was taken, the aircraft entered the stall and the nose pitched sharply down, thus aiding recovery. On the Trident there was no buffeting at approach to the stall with droops extended. On T-tailed rear engine aircraft, design characteristics are such that at the stall the nose tends to pitch up, thus exacerbating the situation. If the stall is allowed to develop, the engines drop into the turbulent flow from the wings. The disturbed airflow causes engine ‘hiccup’ known as a surge, resulting in loss of power. If the stall develops even further, the high tailplane drops into the turbulent flow and elevator control becomes ineffective. The aircraft is now said to be deep-stalled and, with no means of reversing the situation, recovery is virtually impossible. The inherent danger of such a condition was made apparent as early as 3 June 1966 when Trident 1, G-ARPY deep-stalled on a trial flight during stall tests. The aircraft fell flatly from the sky and pancaked onto the ground killing all the test crew on board. For this reason, Tridents, as well other British aircraft with tail-mounted engines, have always been fitted with stick pushers as well as stick shakers.

Pilot training covered thoroughly the recognition of and recovery from, an early approach to the stall condition long before stalling actually occurred. The Trident 1 was also protected with automatic stall warning and recovery devices including a ‘stick shaker’ which physically shook the control column at an early stage approaching the stall condition, and a ‘stick pusher’ which delivered a hefty push forward to the control column at later stall development. On sensing approach to the stall condition, incidence probes on each side of the fuselage would activate electric motors which vibrated the control columns. At stall onset, a pneumatically controlled ram would force the column forward before further stall development. Positioned by the airspeed indicators was an amber ‘stall recovery operate’ lamp which illuminated during function of the stick push and a red ‘stall recovery fail’ lamp which lit up with system failure. An amber ‘low pressure’ warning light  situated forward of the droop lever by the ‘droop out of position’ warning light, was also arranged to illuminate if the integrity of the stick push system was affected by reduction in air pressure  below a certain level. Both stall warning devices had encountered teething troubles in the early days and a general if perhaps inaccurate feeling had been left amongst pilots that the system was unreliable. False warnings had occurred causing genuine concern. It is not difficult to imagine the alarm that might be generated by spurious operation of the stick push during take-off and landing. As a result if the stick push operated in a situation which seemed doubtful to the crew, the tendency was to disconnect the stick pusher even though the warning might be genuine. To inhibit the systems, circuit breakers could be pulled out to cut off power to the electric motors and a ‘stall dump’ lever situated on the left rear side of the central control pedestal, could be selected to deactivate the stick pusher ram by discharging the compressed air outboard.

A number of incidents over the years had highlighted the dangers of inadvertent flap/droop selection and served to emphasize the concern. Normal procedure was to select the flaps up at noise-abatement time, which varied according to circumstances, but was usually about a minute and a half after brake release. The thrust levers would then be retarded to reduce power to the noise-abatement setting. Exceptions to the rule included departures from airports such as Rome where the take-offs over the sea did not require noise-abatement procedures and on these occasions pilots often retracted flaps early to improve climb. A few captains, however, were known to employ the technique more frequently than was permitted, and on a ‘small number of occasions’ flaps had been recorded as being selected up immediately after landing gear retraction at heights below 50 ft. With only the droop lever remaining to be selected up, the normal ‘flap up-power reduction’ sequence was broken. At noise-abatement time, the non-handling pilot could then by force of habit ‘select the only lever available and inadvertently retract the droops’. With the speed, at this stage, some 60 kt below the minimum droop retraction speed, the aircraft would instantly enter the stick push stall regime.
A voluntary and anonymous reporting scheme was introduced within BEA revealed an incident which occurred to a Trident departing Paris, Orly for London, Heathrow in December 1968. The first officer handled the aircraft whilst the captain performed the co-pilot functions. Just after raising the landing gear, the captain without saying anything selected the flaps fully up to improve climb performance. At noise abatement time the inevitable happened. The captain retracted the droops and retarded the thrust levers to noise-abatement climb power. The aircraft immediately sank rapidly from the sky. Fortunately the first officer was aware of the captain’s reputation and was alert to the situation. He was still hand flying the aircraft, and simply pushed the nose down to gain speed as he saw the droop gauge move. Aware of his error, the captain re-extended the droops. The prompt action prevented the operation of the stall warning devices and the aircraft quickly regained its normal flight profile and proceeded to climb steadily away.
In May 1970, a similar event befell a Trident II aircraft bound from London to Naples. The Trident II was, in fact, provided with leading-edge slats instead of droops, but their effect was similar and pilots tended to refer to them as the latter. The incident occurred between 1,200 ft and 1,400 ft, in good visibility and at an indicated airspeed of 175 knots. The captain was handling the aircraft and at noise-abatement time the first officer carried out the procedure. After power reduction, with the P2’s hand just withdrawing from the thrust levers, a stick shake occurred followed very quickly by a stick push. A scan check of the situation by the crew revealed no apparent problem. A few seconds later, another stick shake and push ensued in quick succession. Airspeed an attitude seemed normal and the aircraft was still accelerating. The crew could see the ground and the condition appeared safe. Since no warning lights seemed to be illuminated, the captain assumed the stall warning devices to be malfunctioning and called for the stick to be dumped. On turning to activate the stall dump lever the first officer noticed the droop gauge indicating up and he immediately re-extended the droops. During this period the aircraft ‘just managed to stay flying’.
At the subsequent investigation each pilot denied selecting the droops up, yet extensive examination of the systems revealed no evidence of mechanical malfunction. One of the crew must have operated the droop lever. Strong but inconclusive evidence suggested that the captain involved in this event was the same person in command when the incident occurred departing Orly. It was difficult to avoid the conclusion that the fault lay once again in the practice of non-standard procedures and that the ‘flaps had been retracted early after take-off and the droops had been retracted at noise-abatement time in mistake for the flaps’. These two incidents, more than any other, served to highlight the dangers inherent in the inadvertent retraction. The maintenance of proper procedures was strongly emphasized by management, although any threat of disciplinary action by the company was deemed unwise in the hostile industrial environment. With time the matter faded into the background. Little or no information was circulated on the effects of change of configuration on stall warning and stick push function; few were aware that in such circumstances, with droops retracted early, stick shake and stick push were almost coincidental.

Captain Stanley Key operated his aircraft by the book. Being a route check captain he was aware, more than most, of the importance of adhering to correct procedures. He liked the use of the autopilot, however, rather than hand flying, and he tended to engage it early, although the practice was not acceptable. As he settled in the left-hand seat of the Trident in preparation for departure, the discomfort in his chest must have been becoming more intense. Rain from the worsening weather spattered the windshield in front of him and the aircraft rocked occasionally in the gusty wind. The time was now 16.20 hrs BST (15.20 hrs GMT) and, with scheduled departure only 25 min away, a busy time lay ahead.

BEA’s scheduled flight BE 548 (call sign Bealine 548) from London to Brussels was to depart with each of the 109 seats taken. A world-wide 24-hour strike of pilots had been called by International Federation of Airline Pilots’ Associations (IFALPA) for the next day as a protest against the failure of governments to deal with the problem of hijacking. The effectiveness of the strike could only be surmised, but many passengers were taking no chances and were flying that Sunday evening to avoid possible disruption. A few intending travellers who had not booked tried several times in vain to secure a seat. A maximum payload of passengers and baggage, plus fuel requirements of 8,200 kg resulted in a take-off weight of 50,000 kg. The low fuel figure for the short flight left the Trident still some 2,000 kg short of its maximum take-off weight of just over 52,000 kg, and, if necessary, more fuel could be loaded in the wings, but not another kilo of payload could be carried.

As the last of the passengers boarded the aircraft, the crew continued with their checks. Systems and equipment were tested, allowable defects examined, fuel figures scrutinized, and engine power settings and take-off speeds calculated. In spite of the thoroughness of the procedures, however, one hidden fault remained. Unknown to the crew a locking wire was missing on the three-way valve of the stick push system. A jolt in turbulent flying conditions might be just enough to move the valve and upset the integrity of the device. With power reduction at noise-abatement time any slight misalignment of the valve might affect a small pressure drop. Although the system would not be rendered inoperative, the condition might illuminate the amber ‘low pressure’ warning light situated forward of the droop lever if the system pressure dropped sufficiently low.

Captain Key was to fly the aircraft and he briefed the crew thoroughly on the departure routing. The departure clearance had not been received, but from the flight logs and knowing the runway in use, the crew could speculate on a Dover One standard instrument departure (SID) and could plan accordingly. The Dover One SID required the aircraft to pass over a marker beacon situated about a mile or so off the far end of the runway, then turn left over the town of Staines and track towards the radio beacon at Epsom. The Epsom beacon was to be crossed at 3,000 ft or above and the first height restriction was 5,000 ft. The drills required in the event of an emergency on take-off, and other relevant details were discussed. Each man was to carry out his duty as per the flying manual: the captain would operate the radio as well as fly the aircraft, P2 would handle the throttles, monitor the power, and keep the flight log updated, and P3 would call out the speeds on take-off, monitor the aircraft systems, and oversee the operation.

The flight dispatcher appeared on the flight deck less than 10 min before departure with the details of weight distribution and aircraft trim, presented in the form of a load sheet. The tail plane incidence or angle of tail plane to the airflow, on the Trident was variable, and could be adjusted to redress any out-of-balance forces in flight. Such action was known as trimming the aircraft. The tail plane required for balanced flight just after take-off was marked on the load sheet and would be checked and set accordingly on the tail plane indicator. With the loading and trim details approved and all pre-flight checks completed, the engine start drill was commenced. Start clearance was requested and received on 121.7 MHz at 15.39 hrs GMT (all times GMT) 6 min before departure.

 

 

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Clearance R/T: ‘Bealine 548 cleared to start.’

At the last minute, just as the engines were being started, the flight dispatcher re-entered the flight deck and notified the captain that a Vanguard freighter crew were required in Brussels and would somehow have to be accommodated on the flight. The extra weight placed the aircraft over its payload carrying limit and obliged some load readjustment. The load alterations were undertaken and, a few minutes later with all engines running, the positioning crew boarded the aircraft. One was placed in the last remaining seat left vacant by a babe in arms; another was given a cabin crew seat, whilst the Vanguard captain, John Collins, was allocated the jump seat on the flight deck. Captain Collins had for some years been a Trident first officer before being transferred to the Vanguard fleet for his command, so was an experienced Trident pilot familiar with the aircraft’s systems. He, however, would take no part in the duties of the flight. The three latecomers, added to the 109 passengers and six Trident crew–one stewardess, two stewards, and three pilots–brought the total on board to 118.

With the load adjustment complete, the load sheet updated and he trim rechecked, the aircraft was ready for departure. The passenger doors were closed at 15.58 hrs. Papa India was parked by a passenger walkway facing nose in towards the terminal building and required a truck to push the aircraft clear. At 16.00 hrs Captain Key selected 121.9 MHz and called ‘ground’.

Key R/T
: ‘Ground, Bealine 548 request push.’

With clearance received Captain Key informed the ground engineer on intercom that push back could be commenced. The push back truck by the nose revved its engines in response and Papa India moved away backwards from the gate. The ground engineer remained on intercom and walked out with the aircraft by the nose wheel. The aircraft was positioned on the taxiway and, with push back completed, the aircraft brakes were set to park. The captain had a last word with the ground engineer confirming departure time of 16.00 hrs and requested the all clear. The push back truck was driven while the ground engineer disconnected his head- set and stood safely to one side, arm raised vertically indicating all clear.

Key R/T: ‘Bealine 548, taxi.’

Ground R/T: ‘Bealine 548, cleared to taxi to holding point two eight right.’

The time was 16.03 hrs. While proceeding to the holding point the ‘taxi drills’ were commenced with Ticehurst reading over the intercom from the checklist to which the other two responded. Some aircraft types were known as ‘shouting’ aeroplanes where the crew conversed as normally as possible, leaving one ear free from the headset. On the Trident, however, all speech was conducted via the intercom system. The droops were selected out and the flaps set to 20 degrees. During taxi, Chief Steward Frederick Farey quickly visited the flight deck to confirm the cabin ready for take-off. Approaching the threshold the departure routing was passed to Papa India at 16.06 hrs.

Clearance R/T: ‘Bealine 548, cleared to Brussels, Dover One departure, squawk standby six six one five.’

The clearance, as anticipated, was noted and read back by Ticehurst and was confirmed correct. 6615 was selected on the transponder in preparation for radar identification. On instruction 118.2 MHz was selected, and at 16.06:53 contact was established with the control tower.

Key R/T: ‘Bealine 548, ready for take-off.’

Tower R/T: ‘Bealine 548 cleared for take-off two eight right.’

As Papa India lined up on the runway, a last minute hitch delayed their departure, and the tower was informed that they had a small problem. This could very well have been the illumination of the stick pusher amber ‘low pressure’ warning light. The rain continued to fall heavily in the blustery wind. Just over half a minute later Key called for a second time to indicate readiness.

Tower R/T: ‘Bealine 548 cleared for take-off.’

Key replied simply and abruptly, 548.

The time was now 16.08:24. In the wet conditions, Key held the aircraft stationary on the toe brakes as Keighley advanced the throttles to the reduced power setting calculated by Ticehurst before departure. In spite of the maximum payload being carried, Papa India was still some 2,000 kg short of maximum take-off weight because of the small fuel amount required for Brussels, and to reduce engine wear something less than full power could be set. As Keighley fine-tuned each lever to the calculated setting on the P7 gauges, Key released the brakes and Papa India moved off quickly down the runway. Ticehurst checked the speed increasing while Key steered the aircraft using the nose wheel tiller. As the rudder became effective with speed, Key transferred control, maintaining direction by guiding the rudder with the foot pedals. The wind was blowing from 210 degrees at 17 knots weather cocking the aircraft nose into the wind as the tail acted like a vane and the landing gear as a pivot. A good measure of right rudder was required to hold the aircraft on the centre line. Soon Ticehurst made the first call of ‘one hundred knots’. Below this speed anyone observing danger could call stop, but after 100 knots only the captain could call stop for an emergency, or the P2 for an obvious engine problem. Ticehurst’s next call at 134 knots was ‘V1’, the go or no go decision speed; followed quickly by ‘rotate’ at 139 knots. Captain Key pulled back on the control column and rotated the aircraft to the required nose- up attitude for lift off. Two seconds later at 145 knots, the wheels left the runway and Papa India became airborne. The take- off run had lasted 44 sec and the time as now 16.09:14. Acceleration was still rapid and ‘V2’, the safe climb-out speed required in the event of losing an engine at V1, was quickly achieved and called at 152 knots

With the aircraft safely climbing away the order ‘undercarriage up’ came from Key. Keighley immediately selected the lever to the up position and monitored the light sequence as the landing gear retracted into the wheel bays. Papa India was now buffeting wildly in the wet and turbulent conditions. As the wind began to bite, Key turned the aircraft slightly left to counteract drift and crabbed the aircraft along the extended runway centre line. The speed increased to 170 knots and at a height of 355 ft, 19 sec into the air, the autopilot was engaged. Initial climb speed was based on the take-off safety speed of V2 plus 25 knots and should have been 177 knots indicated, but the speed lock was selected shortly after autopilot engagement with the speed still reading 170 knots, 7 knots slower than requirements. Flying below the target speed in such turbulent conditions was definitely not to be recommended and clearly indicated Key’s increasing discomfort and growing loss of concentration. As Papa India approached the marker, the beacon signal of medium pitched alternating dots and dashes could be heard on the headset accompanied by an amber light flashing in unison on each pilot’s panel.

At 16.09:44, flyng through intermittent cloud, passing 690 ft, the left turn to track towards the Epsom radio beacon was initiated using the autopilot heading control knob. As the aircraft banked 20 degrees to the left, Key made a last call to the tower.

Key R/T: ‘Bealine 548, climbing as cleared.’

Tower R/T:’548, airborne at zero nine, contact one two eight decimal four. Good day.’

Papa India passed 1,000 ft on the altimeter and entered thick cloud, buffeting and rocking in the turbulence. Key was slow to respond to the reply from the tower and not until 5 sec after the call did he simply answer ‘Roger’. Ticehurst quickly dialled 128.4 MHz on the radio selector box. In spite of the bumpy conditions, the auto pilot was holding the speed quite well, with only a knot or two fluctuations on either side of 170 knots. The time was now 16.10:00 and Keighley called ‘ninety seconds’, the noise-abatement time. Three seconds later he selected the flaps from 20 degrees to fully up. As the flaps were running up, Keighley reduced power to the noise-abatement power setting on the P7 gauge. With the power setting, the auto pilot decreased the climb angle in an attempt to maintain speed. At the same time Key called London on 128.4MHz.

Key R/T: ‘Bealine 548 is climbing as cleared, passing 1.500 ft’

London R/T: ‘548, climb to flight level six zero.* Squawk six six one five’.

* At lower heights, the pressure altimeter is set to the local area pressure setting and indicates height above mean sea level (MSL). Above a certain height, which varies throughout the world–at Heathrow at that time, for example, at heights of 6,000 ft and above– the altimeter is set to a standard pressure setting which represents the MSL pressure on an average day. The height at which the altimeter is changed from local to standard pressure setting is known as the transition altitude. Heights below the translation altitude are expressed as an altitude in thousands of feet, e.g.  4,000 ft, and above as a flight level in units of a hundred, e.g.  Flight level (FL) 70 is equivalent to 7,000 ft, and FL 260 to 26,000 ft.

At this point the flaps fully retracted into the wing. Key’s reply to the re-clearance from London was terse and non-standard.

Key R/T: ‘Up to six zero.’

Ticehurst lifted his eyes to switch on the radar transponder, situated above the pilot’s heads, which was set on stand-by with the code 6615 already selected, then made a note of the re-cleared height. Second Officer Keighley also clearly marked his flight log with this instruction to climb.

As the aircraft continued in a sustained 20 degrees banked left turn towards Epsom, bumping around in the cloud, the autopilot was coping less well and the speed dropped to 157 knots, 20 knots below target speed. A more alert pilot, checking progress, would certainly have intervened earlier to correct speed loss, but there is little doubt that by now Key was in pain with his attention wandering. A more confident co-pilot might just have detected the subtle incapacitation being experienced by his captain, but in the absence of obvious signs young Keighley could hardly be blamed for any inaction. He, or Ticehurst, may even have called ‘speed’ and been ignored.

At this normally quiet period of the flight, had the aircraft been climbing safely at target speed, the crew would have been freer to concentrate on the instrument departure route. Epsom and the minimum height required over the radio beacon of 3,000 ft (the minimum height also required for droop retraction), was still a minute or two away. At Epsom the aircraft would be turned towards Dover. The engines would then be advanced to normal climb power and the speed increased. On reaching 225 knots, the minimum droop retraction speed, the wings would be held level and the droops would be selected in. The speed would then be increased to the normal climb speed and the aircraft would continue on its way to destination.

After Papa India’s noise-abatement time, however, the turbulent conditions being experienced in cloud might not have been the only interruption to have upset the crew in the quiet moments expected at some time during the rough ride after take-off, the three-way valve in the stick push ducting moved one-sixth out of position. It is quite possible that on power reduction, the system pressure dropped below the lower limit, illuminating the ‘low pressure’ warning light. ‘This light from its position might conceivably have been mistaken for the droop- out of position warning light. Turning in turbulence at such low speed might also have triggered a stall warning, with the stick shaker operating momentarily. Ticehurst would have turned back to his instrument panel to check the integrity of the system, although under the circumstances it would almost certainly have been genuine. For a moment, at least, his attention would have been distracted. These events could have occurred simultaneously very soon after flap retraction and power reduction.

In Key’s confused state, with knowledge of previous incidents, the alarm bells would have been ringing in his mind. Could he have assumed that young Keighley had retracted the droops instead of the flaps, and if so what would have been his reaction. Would he have called out a warning? A shout of ‘droops’ might just have had the opposite effect than intended and might have prompted Keighley obediently to retract them. Such a call, however, would have undoubtedly been as brusque as Key’s comments on the radio and would have alerted the others on the flight deck. If he genuinely believed the droops to have been retracted early, swift action would be necessary.

Perhaps, instead, Key, with the ‘Dublin incident’ in mind, assumed that Keighley had selected flaps down by mistake, rather than up, thus causing the low speed. His mind would picture flaps selected fully down with droops extended and his thought would be to have the flaps selected back to the up position. In such a configuration, the flap and slat levers would sit side by side. Since the flaps were actually up, only one lever would be apparent and Key may have pointed directly at the droop lever with the odds ‘put that up’. The co-pilot may then have made the selection. With movement of the lever, Key’s mind would picture the flaps set to the up position with the droops still extended, instead of the actual situation of both flaps and droops being selected up.

A similar situation can be envisaged if we imagine Key still relating his low speed to flap drag. He may simply have assumed that Keighley had forgotten to select the flaps up at noise-abatement time. Once again a command of ‘put that up’ could have been actioned. Such theories, however, all seem to contain occurrences which one imagined would have drawn the attention of those on the flight deck to the situation, whereas no one seemed to know what had happened. Whoever moved the droop lever to up seemed to have failed to appreciate the consequences of his action. Of course, the lack of response from the crew could simply have been the result of the overwhelming cacophony of noise which ensued, but is more likely to point to an insidious cause.

If Keighley had moved the droops, for example, he would have to be quick. The period between noise-abatement time and droop-in selection was only 24 sec. In these short moments, Keighley had to select the flaps up, accurately reduce power in the rough conditions– not a simple task– and write up his log with the re-cleared height. Keighley, mistaking Key’s command, could perhaps have rapidly moved the droop lever thus masking his action, as well as performing the other tasks, but he was not known for his swiftness.

If Key was relating low speed to flap drag it would have been easier for him to take action himself. With the attention of the other two pilots drawn to their duties, Key, without saying anything, could simply have moved the only lever available, thinking he was retracting the flaps. If he had, it would not have been the first time such action had been taken, and would go some way to explaining the reason why the person who moved the droop lever failed to appreciate his actions. In Key’s mind the flaps would now be retracted with the droops extended. If his hand was already in the area of the droop lever, setting the level in the height acquire box, he could have moved the droops easily without attracting attention. It is possible that the height acquire box held the solution to the puzzle. If the declared height of 6,000 ft was set in the box then it is possible that Key selected the droops up in error at about the same time as setting the height. If 6,000 ft was not entered, then it is possible that Keighley selected the droops up in error; incorrectly obeying the command ‘put it in’.
The height acquire box was recovered from the wreckage but unfortunately was too badly damaged to be of use. In the end, none of the theories appear likely, and it is possible only to speculate. Since no cockpit voice recorder was on board, it will never be known which pilot retracted the droops.

At 16.10:24, however, only 6 sec after Key’s last sharp radio call and limping through just, 1,770 ft, the droops were most certainly selected in. The speed increased slightly to 162 knots but, at 63 knots below the minimum droop retraction speed, was dangerously low.

Papa India immediately entered the stall regime and the events which followed were swift and dramatic. Within one sec of the droop lever movement, the flashing amber ‘alert’ light on each pilot’s station operated, indicating a problem. The ‘controls’ window of the central instrument warning system (CIWS) display panel also illuminated outlining the fault area, and the droop ‘out of position’ lamp lit up specifying the cause. One second later the stick shaker operated, followed half a second later by the stick push. The amber ‘stall recovery operate’ lamps by the airspeed indicators illuminated with the stick push operation, and, under certain circumstances, there may also have been a fleeting illumination of the red ‘stall recovery fail’ light situated nearby. The ram force pushing the control forward immediately disconnected the autopilot, illuminating the flashing red ‘alert’ light at each pilot’s station and also the red ‘autopilot’ window of the CIWS display panel. A loud audio autopilot disconnect warning was also transmitted to each pilot’s headset. Clang! Clang! Clang! The above sequence would have occurred in something less than 3 sec and would have caused the greatest distress, even to a healthy man. The effect on Key in his condition must have been overwhelming. It was probably at this point, with heart racing, that the pressure of the blood from the tiny ruptured vessel forced separation of the arterial lining. The pain could have been quite acute and his judgement would have been severely affected. In spite of his discomfort, Key instinctively grasped the control column as the nose dropped violently. As the nose able fell the stick push relented allowing Key to dive the aircraft and attempt to fly a recovery, but instead Papa India was held level and the wing bank taken off. No attempt was made to reselect the droops out and the crew were obviously at a loss to their predicament. 

At 16.10:32 the droops moved fully in at the wing leading edges. On retraction of the droops, the centre of pressure, the point through hitch lift is assumed to act, moved forward. Since the variable incidence tail plane was positioned for aircraft trim with droops extended, a tail heavy situation was immediately encountered. In effect, Papa India was trimmed into the stall. The nose pitched up again as the aircraft passed 1,560 ft in a slight descent with the speed increasing to 177 knots. The wings were still almost level with the aircraft heading due south. Two seconds after the movement of the droops fully in, the stick push operated once more. Again the amber ‘stall recover operate’ lights illuminated. For a second time, Key responded by holding the aircraft level rather than letting the nose dive towards the ground. In the turbulent cloud, with no visual reference and height low, the attempts of the stick push to plummet the aircraft earthwards must have been disturbing. Papa India on the point of stall was desperately short of speed, and a steep descent to regain forward motion, or re-selection of droops, was essential. Had the nose been held firmly forward, full power applied and the droops reselected (which would have taken about 10 sec to run) Papa India might well have climbed away safely. In the confusion, the cause of the problem was overlooked and no attempt was made to fly a recovery. The visual and aural warnings during these vital moments must have been overwhelming and could not have aided concentration. Key had omitted to depress the cancel button on the control column for the autopilot disconnect warning, and the red flashing ‘alert’ lights and the loud clang, clang, clang audio warnings continued throughout.

A few moments after the second stick push, the system pushed again for a third time. The nose dropped slightly below the horizon with the force but once more no full recovery was attempted. Suspicious of the integrity of the system, the order was given by Key to dump the air supplying the stick pusher to which Ticehurst responded by selecting the lever to override.

At 16.10:39 Papa India was still descending flatly from the sky, passing 1,275 ft, with the aircraft banking 16 degrees to the right. By now the airspeed had risen to 193 knots, but Captain Key, perhaps sensing the aircraft had recovered and, probably with the normal climb speed 177 knots in mind, pulled back steadily on the column at a constant indicated airspeed of 175 knots. Papa India entered the ‘true aerodynamic stall’ and the nose pitched up once more.

At 16.10:43 descending through 1,200 ft, the aircraft locked into a deep stall with the nose angled 31 degrees in the air. The indicated speed dropped to 54 knots and the airspeed pointer settled on the lower stop. Recovery for Papa India was now impossible. At 1,000 ft he aircraft broke cloud descending at a 60 degrees angle at 4500 ft/min. It is doubtful, with heads down inside the flight deck, whether any of the crew would have seen the ground. In the driving rain, with the noise of the autopilot disconnect warning still clanging in the crew’s ears, Papa India passed over the A30 highway and, just 36 sec after the inadvertent droop lever movement, impacted on its belly near the Crooked Billet roundabout.

The time was 16.11 GMT. The aircraft struck slightly nose down and the tail separated from the main fuselage. Papa India crashed about four miles from Heathrow on a narrow strip of waste ground between the A30 highway and the town of Staines, almost as if it had been deliberately guided to an open area. Not a single structure on the ground sustained as much as a scratch, and even the power lines close by went untouched. Only one person was pulled out alive, but deeply unconscious, from the wreckage and he died later in arrival at Ashford hospital. All 118 on board perished. The accident proved to be the worst in British aviation history and, but for the open site of the crash, could have been much worse.”

Kind courtesy of: Air Disasters by Stanley Stewart Published by Ian Allen England 1986 & Wikipedia.org

 

 

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2 thoughts on “Inexperience “The Trident Tragedy 1972”

  1. All times are GMT
    Door close: 1558
    Pushback: 1600
    Taxi clearance: 1603 BE 548 was cleared to taxi to the holding point adjacent to the start of Runway 27 Right.
    ATC Clearance: 1606. During taxi, at 16:06 the flight received its departure route clearance: a routing known as the “Dover One Standard Instrument Departure”.
    Ready for take-off: 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.
    Ready for take off: At 16:08 Key again requested and received take-off clearance.
    Wind: 210/17 knots
    Brake Release: 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.
    Airborne: 1609:14, Gear up
    Auto Pilot engaged: 1609:33 at 355 feet and 170 knots. Speed lock selected at 170 Knots.
    Passing Middle Marker: 1609:44 at 690 feet. Turn towards Epsom started.
    Standard noise abatement started: 1610. Reduced engine power, flaps retracted 1610:03.

    Passing 1500 feet asl, recleared to Fl 60. Airspeed decreases to 157 knots during turn, 20 knots below target speed.

    Droops retraction started: 1610:24 , the leading-edge devices were selected to be retracted at a height above the ground of 1,770 feet and a speed of 162 knots , 63 knots below the safe droop-retraction speed of 225 knots
    Stall Warning: 1610:25, audio and visual
    Stick Shaker: 1610:26
    Stick push: 1610:27, disconnects auto pilot. Auto pilot disconnect warning horn sounds and continues till impact
    Droops fully retracted: 1610:32, speed 177 knots and altitude 1560 feet.
    Second Stick Shaker: 1610:32
    Second Stick Push: 1610:33
    Third Stick Shaker: 1610:37
    Stall Warning Recovery system overridden: 1610:38
    Aircraft descending:1610:39 to 1275 feet and accelerates 193 knots because recovery action of stall warning system earlier. Aircraft in right 16 degree bank on course. Key tries to adjust speed to 177 knots, the droops extended climb speed by pulling back on the control column.
    Deep Stall: 1610:43, descending through 1200 feet with pitch of 31 degrees nose up. Airspeed less than 54 knots, below indication level.
    1610:55: passing 1000 feet at 4500 feet per minute rate of descent
    Impact: 1611

    The answer lies in the speed adjustment attempt by Captain Key from 193 knots to 177 knots while aircraft is descending after the third stick shaker and stick push by the Stall Warning System Recovery action. The captain is attempting to regain 177 knots why? Because it is the droop extended speed in air meaning he did not give the command for their retraction.

    The whole hulla-balloo started after Keighley initiated droop retraction at 1610:24 as the aircraft climbs through 1770 feet (see above) at a speed of 162 knots, 63 knots below the safe retraction speed for the droops.

    Note: 177 knots is safe extended speed for the droops but for retraction a minimum speed of 225 knots is required.

    Captain Key’s recovery attempts from the stall were not correct but he must have been dumbfounded at the enormity of the error. He was not expecting some idiot to raise the droops. It was suicidal.

    Keighley and Ticehurst were both inexperienced. Keighley was pushed out of the simulator into the cockpit of a modern airliner. He was overwhelmed at that moment.

  2. Even the Almighty couldn’t have altered the situation; the captain was a mere mortal. The Trident stall is different from the stalling of other aircraft with the conventional tail assembly. The Trident has a T-tail assembly which near the stall comes into the downward flow of air from the wing trailing edge, or downwash from the wings. The elevator control in the tail assembly whose input through the pilot raises the nose up or down becomes ineffective in this downwash of air and the nose cannot be brought down by the pilot. To compensate for this, a stick pusher motor is installed which automatically pushes the nose down as the aircraft approaches the stalling angle. A Trident aircraft was lost under the command of John Cunningham during a training flight due to a super stall condition from which they could not recover; hence the stick pusher mentioned above was installed.

    Captain Key had given no command for slats to be raised up. The indicated airspeed had exceeded the slats extended speed of 177 knots. The captain, I believe was trying to get back to that speed by pulling on the control column. Speed and throttle opening to the gate would not matter, as the aircraft stalls when the lift is not produced by the wings because the angle of attack exceeded the stalling angle. The angle of attack is the angle at which the flight path (relative airflow) meets the chord line of the wing of the aircraft.

    The Air France flight which crashed in the Atlantic recently was in a similar situation, it crashed in the same flying attitude, with the nose up.

    I believe we were deliberately led astray towards the captain’s heart attack for which the post mortem would only reveal clogged arteries, which was already known. It maybe as simple as this.

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