Avro 691 Lancastrian accident at Mt Tupungato, Argentina, 2 Aug 1947 (G-AGWH)
On August 2, 1947, an Avro 691 Lancastrian (registration G-AGWH) operated by British South American Airways - BSAA was involved in an aviation accident near Mt Tupungato, Argentina in flight. 11 people were killed. Investigators recorded the probable cause as: In 1947, through lack of evidence due to no wreckage having been found, the cause of the accident remained obscure. The possibility of severe icing cannot be ignored. This summary draws on records from the Bureau of Aircraft Accidents Archives (B3A); 6 related events involving the same aircraft type or operator are linked below.
Probable cause
In 1947, through lack of evidence due to no wreckage having been found, the cause of the accident remained obscure. The possibility of severe icing cannot be ignored. Later, in 2001, an investigation commission conducted by Argentinian and British experts concluded that the accident was probably caused by a premature descent on part of the crew due to strong head winds. The presence of strong winds at high altitude reduced the speed of the aircraft and the crew was not aware of these winds. Due to lack of visibility, the crew started the descent and was not able to distinguish the mountains.
— NTSB Determination
Accident narrative
After passing over Mendoza, enroute to Santiago de Chile, the crew encountered poor weather conditions with strong winds (up to 180 km/h) and heavy snow falls. While cruising at an altitude of 15,000 feet, the four engine aircraft christened 'Star Dust' hit the slope of Mt Tupungaro located in the Argentinian Andes. As the airplane failed to arrive, SAR operations were conducted but eventually suspended few days later as no trace of the aircraft nor the crew was found. About 53 years later, in 2000, an official mission conducted by Argentinian Army Officers and Scientists was organized to find the aircraft. Few debris and three bodies were found and repatriated down to the valley.
Probable cause (official findings): In 1947, through lack of evidence due to no wreckage having been found, the cause of the accident remained obscure. The possibility of severe icing cannot be ignored. Later, in 2001, an investigation commission conducted by Argentinian and British experts concluded that the accident was probably caused by a premature descent on part of the crew due to strong head winds. The presence of strong winds at high altitude reduced the speed of the aircraft and the crew was not aware of these winds. Due to lack of visibility, the crew started the descent and was not able to distinguish the mountains.