BOAC Flight 781
| British Overseas Airways Corporation Flight 781 | |
|---|---|
 an identical BOAC de Havilland Comet 1 |
|
| Accident summary | |
| Accident type | Crash from decompression |
| place | south of Elba 42 ° 36 ′ 38.2 " N , 10 ° 16 ′ 53.4" E |
| date | January 10, 1954 |
| Fatalities | 35 |
| Survivors | 0 |
| Injured | 0 |
| Aircraft | |
| Aircraft type | De Havilland DH.106 Comet 1 |
| operator | British Overseas Airways Corporation |
| Mark | G-ALYP |
| Surname | Yoke Peter (callsign) |
| Departure airport | Rome Ciampino Airport |
| Destination airport | London Heathrow Airport |
| Passengers | 29 |
| crew | 6th |
| Lists of aviation accidents | |
The British Overseas Airways Corporation flight 781 ( flight number : BA781) was an international scheduled flight from Rome Ciampino Airport to London Heathrow in which a British Overseas Airways Corporation plane crashed on January 10, 1954.
plane
The aircraft of the type De Havilland DH.106 Comet 1 with the aircraft registration G-ALYP was equipped with 4 de Havilland Ghost 50 engines. It had space for 36 passengers. The G-ALYP was the first Comet in series production after two prototypes and had its maiden flight on January 9, 1951. It was delivered to British Overseas Airways Corporation (BOAC) on April 8, 1952. The Comet 1 was the first jet aircraft in scheduled service and BOAC the first airline to operate in 1952.
Crew and passengers
At 31 years old, flight captain Alan Gibson was one of the youngest pilots in the BOAC. He had flown for the Royal Air Force and with BOAC since 1946 and had now completed around 6,500 flight hours. In 1951 he was already involved in an emergency when he had to make an emergency landing on a Hermes . He had been commended for his exemplary behavior in this no-fault incident. The first officer on Flight 781 was William John Bury, 33, with 4900 hours of flying experience. The flight engineer was Francis Charles Macdonald (27) and the radio officer Luke Patrick McMahon (32).
There were 10 children among the 29 passengers. Prominent BBC journalist Chester Wilmot was among the victims .
Flight history
On January 10, 1954, the de Havilland Comet started at 9:31 a.m. in Ciampino and rose to the cruising altitude of 8,300 meters. At around 9:51 a.m., communication between the pilot and a second BOAC machine suddenly broke off. The plane crashed into the sea off the island of Elba . The fall was observed by fishermen. The 29 passengers and 6 crew members on board were killed.
Search for the plane and initial investigations
The search for the plane began with the HMS Barhill the Royal Navy and the salvage ship Sea Salvor from Malta . A group of Italian fishermen had seen the crash and rushed to the crash site to look for survivors, but were only able to recover a few bodies. The victims were taken to Italy for autopsy. The pathologist responsible, Antonio Fornari, discovered cracks in the skull, and especially tears in the lungs. These could be traced back to a sudden drop in cabin pressure.
The aircraft wreck was discovered on the ocean floor, lifted and taken to the Royal Aircraft Establishment in England for investigation. When inspecting the wreck, it became apparent that the aircraft had broken apart while still in the air. The cause was initially assumed to be a bomb, then an engine explosion. All Comet 1 had to stay on the ground and the turbines were reinforced. The possibility of a drop in cabin pressure was also discussed but was rejected because it was certain that the machines had already been secured against it far above the norm.
While the first official investigations began, BOAC put its Comet machines back into service on March 23rd. But on April 8, 1954, the airline lost another aircraft with G-ALYY: The charter flight “South African Airways 201” from Rome to Egypt crashed 33 minutes after take-off. 14 passengers and 7 crew members were killed.
Search for the cause of the accident
A closer examination and reconstruction of the aircraft wreck revealed evidence of a sudden drop in pressure in the fuselage:
- Parts of the cabin carpeting were found in the stern area of the fuselage.
- A coin was found in the back of the machine on a part of the body
- Paint streaks and fabric abrasion on the rear of the machine came from the passenger seats
Since large parts of the aircraft could be reassembled, it was discovered that the failure of the fuselage structure had originated from a hatch in the roof of the cabin. The hatch had come loose and hit the tailplane. The tail of the aircraft broke off, the outer wing skin tore, and the wing was torn off. Then the cockpit broke off and the fuel from the wings set the remaining fuselage on fire.
To find out what caused the first crack, the BOAC handed over one of their oldest machines, the G-ALYU, for the investigations. By then the G-ALYU had already completed 3539 flight hours. On May 29, 1954, the built-in machine began to be subjected to typical load cycles during a flight in a water tank built by the Royal Aircraft Establishment . A ten-minute cycle comprised the transfer of the take-off load acting on the wings via the landing gear, the build-up of overpressure in the water-filled cabin, the subsequent pressure reduction during the approach and finally the transfer of the landing load to the wings. The advantage of using water was that it was incompressible and the hull would not completely disintegrate if the structure failed. The experiment ran 24 hours a day, seven days a week, with a ten-minute cycle corresponding to a flight duration of three hours. Together with the operating hours already flown and the flight cycles in the tank, the simulation resulted in a total of 9,000 flight hours.
The tests showed that the accident was triggered by a pressure drop in the cabin. The reason for this was a weak point on the frame of a window of the radio compass in the fuselage roof. This window was part of the navigation system and was made of transparent fiberglass-reinforced plastic . The defect was a result of the fact that the frame had been riveted and not glued as it was originally intended. In addition, the rivet holes were punched and not drilled. This resulted in hairline cracks (visible under the microscope) that had led to fatigue or fatigue fracture .
Individual evidence
- ↑ a b Barry Jones: DH106 Comet - The star that fell to earth (Database) . In: Airplane Monthly April 2010, pp. 65 ff.
- ↑ Aircraft accident reports on incidents with Comet 1A , ntsb.org, accessed on April 5, 2014 (PDF)
- ↑ "1954: Comet jet crashes with 35 on board," BBC News, Jan. 10, 2014
- ↑ a b Flight accident BOAC flight 781 , Aviation Safety Network
- ^ TR Nelson: Falling Stars - Investigation of Comet Accidents, Part 2 . In: Airplane Monthly November 1993, pp. 20 ff.
- ^ Fuselage of de Havilland Comet Airliner G-ALYP ( Memento from April 7, 2014 in the Internet Archive ), Science Museum, London, September 24, 2009