Accident description
Last updated: 29 July 2014
Status:Final
Date:Sunday 18 June 1972
Time:16:11 UTC
Type:Hawker Siddeley HS-121 Trident 1C
Operator:British European Airways - BEA
Registration: G-ARPI
C/n / msn: 2109
First flight: 1964
Crew:Fatalities: 9 / Occupants: 9
Passengers:Fatalities: 109 / Occupants: 109
Total:Fatalities: 118 / Occupants: 118
Airplane damage: Destroyed
Airplane fate: Written off (damaged beyond repair)
Location:near Staines (   United Kingdom) show on map
Phase: Initial climb (ICL)
Nature:International Scheduled Passenger
Departure airport:London-Heathrow Airport (LHR/EGLL), United Kingdom
Destination airport:Brussel-Zaventem Airport (BRU/EBBR), Belgium
Flightnumber: 548
Narrative:
Flight BE548 was a scheduled passenger service from London to Brussels. Start-up clearance was given at 15:39 for a scheduled departure time of 15:45. Push-back was not requested until 16:00 due to load re-adjustment. Clearance to taxi was given at 16:03. The HS-121 Trident taxied to runway 28R for takeoff. At 16:06:53 the crew reported ready for take-off. Takeoff clearance was given and at 16:08:30 the brakes were released.

The standard BEA practice for this particular flight involved a take-off with 20░ flap, leading edge droop (wing leading edge slats) extended and the engine thrust at settings below full power. After take-off speed should be increased to the initial climb speed VNA (ie, take-off safety speed, V2 plus 25 knots). The scheduled value of VNA for this flight was 177 knots Indicated Air Speed (IAS). At 90 seconds from brakes-off flaps are to be selected fully up and the engine thrust reduced to the noise abatement settings. At 3,000 feet climb power is to be set and then as the aircraft accelerates and reaches 225 knots the leading edge is retracted and the en route climb established. The minimum droop retraction speed is placarded by the lever and is well-known to all pilots.

The take-off was normal and at 42 seconds the aircraft rotated, leaving the runway 2 seconds later at 145 knots IAS. At 63 seconds the autopilot was engaged 355 feet above the runway at 170 knots IAS; the IAS speed lock was selected shortly thereafter. At 74 seconds the aircraft started a 20░ banked turn to port towards the Epsom Non-Directional Beacon (NDB). At 83 seconds the captain reported 'Climbing as cleared'. He was then instructed to change frequency and contact London Air Traffic Control Centre.
At 93 seconds the noise-abatement procedure was initiated. On the assumption that the captain was the handling pilot, this would involve the second officer selecting the flaps fully up and operating the thrust levers to reduce power to the pre-calculated figure. At 100 seconds the captain called 'Passing 1500' and at 103 seconds the aircraft was cleared to climb to Flight Level 60. This message was acknowledged by the captain at 108 seconds with the terse call 'up to 60'. This was the last message received from the flight.
At second 114 when the airspeed was 162 knots and the altitude 1,772 feet, the droop lever was selected up putting the aircraft into the area of the stall as the droop started to move. At second 116 the stick-pusher stall recovery device operated, causing the autopilot automatically to disengage and the nose of the aircraft to pitch down and the stick-push to cease as the incidence decreased. Since the elevator trim would stay at its position on autopilot disengagement which at that speed with the droop up would be - the incidence then increased causing a second stick-push at second 124 and a third at second 127. At second 128 the stall recovery system was manually inhibited by pulling the lever. The aircraft then pitched up rapidly, losing speed and height, entering very soon afterwards the true aerodynamic stall and then a deep stall from which at that height no recovery was possible. Impact was at second 150 in a field next to the A30 motorway .


PROBABLE CAUSE: Immediate causes were:
1) Failure by PIC to achieve and maintain adequate speed after noise-abatement procedures; 2) Droop-retraction 60kts below minimum speed.; 3) Failure to monitor speed error and to observe droop lever movement.; 3) Failure to diagnose reason for stick-pusher operation and warnings; 4) Operation of stall recovery override lever.
A factors was a.o. the abnormal heart condition of the captain.

Classification:
Improper flap/slat usage
Loss of control

Sources:
» Air Disasters / Stanley Stewart

Official accident investigation report
investigating agency: Air Accidents Investigation Branch (AAIB) - U.K.
report status: Final
report number: AAIB AAR 4/73
report released:14-APR-1973
duration of investigation:300 days (10 months)
download report: Trident 1, G-ARPI. Report of the Public Inquiry into the causes and circumstances of the accident near Staines, on 18 June 1972 (AAIB AAR 4/73)

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Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from London-Heathrow Airport to Brussel-Zaventem Airport as the crow flies is 348 km (217 miles).

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HS-121 Trident

  • 6th loss
  • 117 built
  • worst accident
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 United Kingdom
  • worst accident (at the time)
  • 2nd worst accident (currently)
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