On July 27, 1992, a Vickers Viscount (registration XA-SCM) operated by Aero Eslava was involved in an aviation accident near Mexico City, Mexico during landing or approach. 4 people were killed. Investigators recorded the probable cause as: Controlled flight into terrain after the crew failed to maintain FL120 as instructed by ATC while completing an IFR approach. It was reported that the copilot was not certified to act as a pilot on this type of aircraft. This summary draws on records from the Bureau of Aircraft Accidents Archives (B3A).
During an approach to Mexico City-Benito Juarez Airport in poor weather, the crew descended below their cleared altitude of FL120 and struck Mt Xocotlihuipa, destroying the aircraft and killing all four occupants.
Incident
While approaching Mexico City-Benito Juarez Airport, the crew received clearance to descend from flight level 150 (FL150) to flight level 120 (FL120). Weather conditions were poor at the time. The crew continued the descent below FL120, and at an altitude of 10,130 feet, the aircraft struck the slope of Mt Xocotlihuipa. The mountain is located approximately 30 kilometers east of the airport. The impact destroyed the aircraft, and all four occupants were killed.
Probable Cause
The official investigation determined the probable cause to be controlled flight into terrain after the crew failed to maintain FL120 as instructed by air traffic control while completing an instrument flight rules (IFR) approach. Additionally, it was reported that the copilot was not certified to act as a pilot on this type of aircraft. The experience of the captain was also noted to be limited.