Last flight of HS 121 Trident 1 ‘Papa India’ on 18 June 1972

Source:Island

AND IMPACT ON ACCIDENT INVESTIGATION

It is said that when two or three airline pilots gather together, they speak about the ‘four Ss – namely, Safety, Security, Seniority and Salary! In the sixties and seventies, British European Airways (BEA) was no different. Their local chapter would have been a member of the British AirLine Pilots’ Association (BALPA), which in turn was a founder member of the International Federation of Airline Pilot Associations (IFALPA) even recognised by the United Nations. These matters are discussed at length at various fora.

In those days, traditionally, there was quite a gap between the pay of senior pilots and juniors. These matters came up regularly for discussion. The British aviation authorities had realised, at the end of the 1950s, that soon they would be running short of Airline Captains who were mainly WWII veterans as they would retire soon. Therefore, a scheme was put in place to train captains at an airfield called Hamble, Hampshire (Hamble College of Air Training) with essentially two streams of recruitment from school leavers and graduates. Previous flying experience was not a requirement. The other main flying school which cadets were hired from was ‘Oxford’. The products of Hamble and Oxford were very good, efficient, militant and vociferous about pay and conditions. There was a difference of opinion between seniors who flew aircraft as a passion and the juniors who were more career-minded. That’s how the process of ‘industrial action’ was initiated by the latter.

Unlike their captains (of the ’old school’) who drifted into flying after WW II, the young pilots were trained to be airline captains of tomorrow. While they were well versed in theory of flight and leadership, they still lacked the all-important experience, which was still the domain of the senior captains.

On 18 of June 1972, a war veteran, and training captain, by the name of Stanley Key, on standby duties, was activated by BEA to fly to Brussels, Belgium, along with two young low-time Second Officers (S/Os). Capt. Key was an anti-strike activist, so well-known for his dissenting views that there was even graffiti on board some of the aircraft flight decks including that of ‘Papa India’, referring to him.

When Capt. Key reported for duty for flight BEA 548 (Radio call sign ‘Beeline 548), he was accosted by a militant, Senior F/O who was not a member of his crew, in the crowded Crew Room. With just four years before retirement (he was 51 years old at the time), his views against strike action were very strong. He is supposed to have got into a heated argument. This was witnessed by many including S/O J W Keighley, one of Capt Key’s crew members. It was also reported that Capt Key apologised for his outburst almost as quickly as it started. It is not certain whether S/O Ticehurst, Key’s other S/O, was also there. They were both flying with Capt. Key for the first time. The aggressive demonstration of the Captain’s feelings would have had some negative effect on the two young S/Os of his crew. It wasn’t a good first impression. 

HS 121 Trident

The aircraft that they were flying that day was a HS 121 Trident 1 registered as G-ARPI, known by all at BEA, as ‘Papa India’, the phonetics of the last two letters. The Trident aircraft was well ahead of its time with a perfectly shaped wing for high speed flight at high altitude with engines at the rear and a ‘T shaped’ tail. In fact, it was the fastest civil jet plane before the advent of the Anglo French Concord! It could cruise at 90% the speed of sound. It could also carry out Instrument Landings in very low visibility–– even in fog as thick as pea soup! The Trident 1 was an aircraft designed to operate with the Captain seated on the left-hand side Flight Deck Seat and of the two S/O’s. Usually, one S/O, known as the ‘Monitoring Pilot’ operates the Flight Engineer’s Systems Panel located behind the two pilots outbound from London Heathrow while the other S/O would sit on the right-hand side seat with the controls. On the return (inbound) leg, the two S/O’s will swap seats and their functions. To operate the Flight Engineers Panel, the Monitoring Pilot had to undergo additional training under the watchful eye of a BEA Supervisory First Officer (F/O) (seated on a fourth seat behind the captain) until the trainee demonstrates competency and was ready to operate the panel by himself. Supervisory functions were additional duties for senior F/Os and because of the prevailing industrial action, they had opted to withdraw from these additional duties. As a direct result of that, there were S/Os who could carry out Right Hand Seat duties only and could not sit on the Monitoring S/O’s panel. Therefore, as far as Capt Key’s crew was concerned, the monitoring Pilot, S/O Ticehust though more experienced, could not relinquish his seat to the low-time S/O Keighley and had to be operating the panel on both outbound and inbound legs. Captains, if they had a choice, usually prefer to have the most experienced pilot in the co-pilot’s seat.

Because its wing was made for high-speed flight it had to be modified with the use of Leading Edge and Trailing Edge high lift devices enabling it to fly low and slow for take-off and landing. At the trailing end of the wing there were the flaps which in effect increased the area of the wing. In the leading edge were devices called ‘Wing Droops’, which, when extended, altered the curvature of the wing and smoothened out the airflow over the wing allowing it to fly at a relatively slow speed.

That afternoon, along with Capt. Key, and his junior two crew members, there was also a Capt. Collins, a freighter Captain, occupying the fourth seat in the Flight Deck. While the weather was overcast at a thousand feet, to witnesses all seemed normal on BEA 548 on the taxi, start up and take off from London, Heathrow, in a westerly direction. Then it commenced a left turn to an East bound heading as required by the departure procedure. Then, suddenly the aircraft which was supposed to climb to 6000 ft, started losing height and crashed in a nose high attitude with hardly any forward motion. It was obvious to the investigators that the aircraft had fallen out of the sky, killing all six crew and 112 passengers on board. This was all within two and a half minutes after brakes release.

A small boy, at Stains, witnessed the accident and informed a neighbour, a retired nurse who was the first to be at the scene. She found only one person alive who sadly died a while later.

Immediately after arriving on the scene the accident investigators from the Accident Investigation Branch (AIB) of the Board of Trade, realised that the Trident aircraft had descended on a steep trajectory as it had cleared some high tension wires before impacting the ground a few yards away and didn’t move forward.

The Accident Investigators had the luxury of using two Flight Data Recorders which were installed on board.

The wreck of ‘Papa India’ was carefully moved piece by piece to a Royal Aircraft Establishment (RAE) hangar at Farnborough airport in Hampshire, assembled, thoroughly examined and mechanical failure ruled out.

Noise Abatement Departures

Because of noise considerations, in the neighbourhood outside the airport, it was a mandatory requirement that Trident Jets climb at Take-off Power to as high as possible with the wheels selected up, wing droops extended and trailing edge flaps selected to 20 degrees, within the airport premises. Then at 90 seconds after brakes released, they had to reduce engine power and retract the trailing edge flaps and then climb to 3000 ft before the Wing Droops were to be retracted after achieving 225 kt. climbing speed. There were two separate leavers to control the Flaps and the Wing Droops.

On analysing the Flight Data Recorders which were in good working order, the investigators discovered that one of the four crew members (Capt Key, S/O Keighley. S/O Ticehurst or Capt Collins) had prematurely retracted the leading edge Wing Droops, before reaching 3000 ft and 225 kt. When the Wing Droops were retracted, the control columns of both Key’s and Keighley’s mechanically shook (vibrated) to give tactile warning that the aircraft is about to stall. No corrective action was taken like re-extending the Wing Droops or increasing speed by the pilots, an automatic pneumatically operated stick pusher activated, sharply reducing the nose-up attitude. In fact, the investigators found that it had happened twice and then someone had deactivated the stall warning (Stick Shaker and Pusher) system. By whom and with what intention, was a mystery. Because the Stick Shaker and the Stick Pusher activated in quick succession someone could have assumed that the system was malfunctioning. The aircraft then entered a deep stall from which it was impossible to recover as there is no airflow over the tail to enable the pilot to push the nose down, by then a well-known phenomenon in ‘T’ tail aircraft. (On 3 June 1966, Trident 1C registration G-ARPY entered into a deep stall while on a test flight and crashed at Felthorpe, Norfolk, killing all four crew members)

How the airflow over the tail of a Trident Aircraft gets disturbed by the wing, at high nose-up attitude and develops into an unrecoverable Deep Stall. The Blue arrow is the relative flow of the air. (See figure 1)

 The post mortem examination of three of the four crew members proved to be normal while Capt Key’s heart was found to be in bad shape through the years and was experiencing a heart attack just before his violent death. Was it due to the argument he had with the senior F/O about 90 minutes before his flight and the resultant rise in blood pressure? How was he classified as ‘fit to fly’, after a seemingly normal Electrocardiogram (ECG) at his last Medical Examination a few months before for renewal of his flying licence? Did the Captain’s heart attack create a distraction to the rest of the crew? Was the Captain obviously incapacitated for the others to see? The last radio call from the Air Traffic Controller was acknowledged by him. Was it a case of subtle incapacitation then? Why didn’t S/O Keighley take over and fly as he was supposed to do? Was he confused as regards the flaps and Wing Droops control handles? Was the ‘intra cockpit authority gradient’ between Capt Key and S/O J W Keighley too steep and made the 22-year-old S/O freeze at the controls? Why didn’t S/O Ticehurst do or say anything? Did Capt. Collins, who was also an experienced Trident Pilot, do or say anything to help?  A host of questions needed to be answered.

Geoffrey Lane the Commissioner of the Public Inquiry to this unfortunate accident in his report stated, “There is a danger of assuming that we have all the facts before us and that the only problem is to assemble them in the right order. Had we had the benefit of a cockpit voice-recorder this might have been true. As it were there may well be some vital piece of information missing which would, if known, change the whole picture”

The report went on to state, “This accident has shown that data as to the height, speed, attitude and movement of controls of the aircraft, however valuable as eliminating any suggestion of mechanical failure, do not always provide as full a picture as possible. The investigator is still left in the dark as to what was passing between the crew members by way of orders, comment or exclamation.”

Within a year of the Accident Investigation Report going public, the UK Board of Trade mandated that all turbine powered in the UK registered civil aircraft above the weight of 5700 kg shall have Cockpit Voice Recorders (CVRs). Australia and America were already using Cockpit Voice Recorders. The International Civil Aviation Organisation (ICAO) also followed suit. Hawker Sidley, the manufacturer of the HS 121 Trident also installed a speed lock to prevent the Wing Droops being retracted below 225Kt. The Trident was the first British aircraft with leading edge high lift devices. Similar American Aircraft, like the more successful Boeing 727, had only one Flap/Slat handle to control all leading edge and trailing edge device eliminating confusion. There were allegations that the original ‘tri jet’ concept was stolen by the Americans.  But that’s another story!

The Boeing 727 with another type leading edge (Kruger) Flaps out (different to Trident Wing Droops).

It was also pointed out by the Report that BEA Technical Crew had neither been briefed nor trained on handling incapacitated crew members at critical stages of the flight.

The report also highlighted that the ECGs for pilot licence medical examinations should not be carried out on pilots at rest only (in bed), but regular Stress ECGs should also be carried out. The critics say that Capt. Stanley Key’s heart condition was a one-off case. We are medically examining Airline Pilots and not Astronauts! The retirement age for pilots is now 65 years, the last five years of which includes, ‘Blood work’ and stress ECGs amongst other routine medical tests.

Flight BEA 548 was the deadliest plane crash on the British soil until the Pan Am crash in Lockerbie Scotland.