BOAC Flight 781
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| Summary | |
|---|---|
| Date | 10 January 1954 |
| Type | In-flight metal fatigue failure |
| Site | Mediterranean off Elba |
| Fatalities | 35 |
| Injuries | 0 |
| Aircraft | |
| Aircraft type | de Havilland Comet 1 |
| Operator | British Overseas Airways Corporation |
| Tail number | G-ALYP |
| Passengers | 29 |
| Crew | 6 |
| Survivors | 0 |
BOAC Flight 781, a de Havilland Comet 1, took off from Ciampino Airport in Rome, Italy en route to London Heathrow Airport in London, United Kingdom on the final stage of its flight from Singapore. The flight crashed, killing all aboard at around 10:00 GMT on January 10, 1954. The flight was operated by British Overseas Airways Corporation (BOAC) using the aircraft G-ALYP ("Yoke Peter").
Contents |
[edit] Flight and disaster
On January 10, 1954, the flight took off at 09:34 a.m. GMT for the final stage flight to London.
At about 09:50 GMT a passing BOAC Argonaut G-ALHJ spoke to Yoke Peter, during which the radio communication was abruptly cut-off. At about this time wreckage was seen falling into the sea by a fisherman.
[edit] Search, recovery and investigation
An extensive search for the aircraft was organised including the Royal Navy ship HMS Barhill and the civilian salvage vessel Sea Salvor from Malta.
Wreckage of the aircraft was eventually found on the sea floor and subsequently raised and transported to the Royal Aircraft Establishment, Farnborough, for investigation. Upon examination of the wreckage it became obvious that the aircraft had broken up in mid-air, and initially it was thought that the aircraft might have been brought down by a bomb, but suspicion then shifted to the possibility of an engine turbine explosion and modifications were put in hand to encase the turbine ring in other Comets with armour plate, to contain a possible disintegrating turbine disk. In the meantime, all Comets were to be grounded until these modifications had been carried out. The possibility of failure of the pressure cabin had been considered but then discounted due to the Comet's cabin having been designed to a considerably higher strength than was considered necessary at the time.
[edit] Metal fatigue
After extensive testing of the Comet 1 G-ALYU ("Yoke Uncle") which had been donated for testing by BOAC, investigators at the RAE concluded that the crash had been due to failure of the pressure cabin at the forward ADF window in the roof (hatch used by the navigator [for use of a bubble sextant] as such it would probably have been located further forward than the location shown on the present diagram), as a result of metal fatigue caused by the repeated pressurisation and de-pressurisation of the aircraft cabin.
The Comet's pressure cabin had been designed to a safety factor comfortably in excess of that required by British Civil Airworthiness Requirements (2.5x P as opposed to the requirement of 1.33x P and an ultimate load of 2x P, P being the cabin 'Proof' pressure) and the accident caused a revision in the estimates of the safe loading strength requirements of airliner pressure cabins.
In addition, it was discovered that the stresses around pressure cabin apertures were considerably higher than had been appreciated, especially around sharp-cornered cut-outs, such as windows. As a result, future jet airliners would feature windows with rounded corners, the curve eliminating a stress concentration. This was a noticeable distinguishing feature of all later marks of the Comet.
[edit] See also
[edit] References
- Air Disasters by Stanley Stewart - Arrow Books (UK) 1986/89 - ISBN 0-09-956200-6
- Report of the Public Inquiry into the causes and circumstances of the accident which occurred on the 10th January, 1954, to the Comet aircraft G‐ALYP - Official Report - 1955
- "Seconds From Disaster" " Crash of the Comet" on National Geographic Channel.
