The Aerolineas Argentinas flight took off from Mendoza at 18:47 for a flight to Cordoba. Severe turbulence existed in the area near Cordoba, causing the flight crew to decide to divert to La Rioja. At 21:25 they reported a La Rioja ETA of 21:40. Nothing more was heard from the flight. The wreckage was found on April 26 near Sierra de Vilgo. PROBABLE CAUSE: “For reasons which could not be determined the aircraft deviated from the prescribed route and followed a course which led it to crash in mountainous terrain. A contributing factor was: The pilot-in-command’s decision to descend below the minimum altitude specified for weather conditions requiring an instrument approach, contrary to the provisions of the Airline Operations Manual. A probable contributing factor was the probable fatigue of the aircraft crew.”