On 10 January 1954, a de Havilland Comet passenger jet operating the flight suffered an explosive decompression at altitude and crashed, killing all 35 people on board.

[3] Its loss marked the second in a series of three fatal accidents involving the Comet in less than twelve months, all caused by structural failures; it followed the crash of BOAC Flight 783 near Calcutta, India, in May 1953, and was followed by the loss of South African Airways Flight 201 in April 1954, which crashed in circumstances similar to 781 after departing from Ciampino Airport.

[8] Among the casualties were Chester Wilmot, a prominent Australian journalist and military historian working for the BBC, and Dorothy Beecher Baker, a Hand of the Cause of God for the Baháʼí Faith.

[8] The full itinerary was: Singapore, Bangkok, Rangoon, Calcutta, Karachi, Bahrain, Beirut, Rome, and finally London.

Gerry Bull, a former BOAC engineer, said that when he performed a preflight inspection of the aircraft in Rome he looked for "incidental damage", and as he did not find any, he believed the Comet was fit for flight.

[4] In its issue dated 11 January 1954, The New York Times published a report stating that a British Comet jet airliner had plunged into the sea near the western coast of Italy, specifically between the islands of Elba and Montecristo.

Extensive recovery operations were carried out overnight, yet despite thorough searches in the frigid waters, prospects of finding any survivors were bleak.

The search effort involved the pioneering use of underwater TV cameras, developed by a team at the UK Admiralty Research Laboratory led by George MacNeice, to help to locate and salvage the wreckage in deep water.

He also discovered in most of the victims a distinct pattern of injuries, consisting of fractured skulls and ruptured and otherwise damaged lungs, which he identified as the actual cause of death.

In order to simulate the crash, the investigators deliberately ruptured the model fuselage by increasing the air pressure inside until it exploded.

The movement of the dummies within the air cabin revealed the cause of the skull fractures: at the moment that the fuselage exploded, they were thrown out of their seats and slammed head-first into the ceiling.

The airline emphasized that the planes had not been officially grounded by the British government, but that the action was being taken as "a measure of prudence to enable a minute and unhurried technical examination of every aircraft in the Comet fleet to be carried out at maintenance headquarters at London airport.

"[13] While the official investigation efforts began, BOAC were determined to return their Comets to passenger service as soon as possible, and succeeded in doing so on 23 March, just ten weeks after the crash.

Sir Arnold Hall, a Cambridge University scholar and scientist and then-head of the RAE, was appointed as the head accident investigator.

[10] After the equivalent of 3,000 flights simulated with G-ALYU, investigators at the RAE were able to conclude that the crash of G-ALYP had been due to failure of the pressure cabin at the forward ADF window in the roof.