On 2 August 1947, Star Dust, a British South American Airways (BSAA) Avro Lancastrian airliner on a flight from Buenos Aires, Argentina, to Santiago, Chile, crashed into Mount Tupungato in the Argentine Andes.

The accident aircraft, an Avro 691 Lancastrian 3, was built as constructor's number 1280 for the Argentine Ministry of Supply to carry thirteen passengers, and first flew on 27 November 1945.

[10] However, Star Dust never arrived, no more radio transmissions were received by the airport, and intensive efforts by both Chilean and Argentine search teams, as well as by other BSAA pilots, failed to uncover any trace of the aircraft or of the people on board.

[12] A report by an amateur radio operator who claimed to have received a faint SOS signal from Star Dust initially raised hopes that there might have been survivors,[11] but all subsequent attempts over the years to find the vanished aircraft failed.

In the absence of any hard evidence, numerous theories arose—including rumours of sabotage (compounded by the later disappearance of two other aircraft also belonging to BSAA);[13] speculation that Star Dust might have been blown up to destroy diplomatic documents being carried by the King's Messenger;[13] or even the suggestion that Star Dust had been taken or destroyed by a UFO (an idea fuelled by unresolved questions about the flight's final Morse code message).

[11] In 2000, an Argentine Army expedition found additional wreckage—including a propeller and wheels (one of which had an intact and inflated tyre)—and noted that the wreckage was well localised, a fact which pointed to a head-on impact with the ground, and which also ruled out a mid-air explosion.

[13] Some BSAA pilots, however, expressed scepticism at this theory; convinced that Cook would not have started his descent without a positive indication that he had crossed the mountains; they have suggested that strong winds may have brought down the craft in some other way.

[18] Star Dust is likely to have flown into a nearly vertical snowfield near the top of the glacier, causing an avalanche that buried the wreckage within seconds and concealed it from searchers.

[10] The Chilean Air Force radio operator at Santiago airport described this transmission as coming in "loud and clear" but very fast; as he did not recognise the last word, he requested clarification and heard "STENDEC" repeated twice in succession before contact with the aircraft was lost.

[10] The staff of the BBC television series Horizon—which presented an episode in 2000 on the Star Dust disappearance—received hundreds of messages from viewers proposing explanations of "STENDEC."