What happened
A scheduled flight departed Vigo airport at 15:40 for Madrid, carrying 16 passengers and a crew of 5. Operating under IFR at flight level 95, the aircraft reported passing Guinzo de Lirnia through cloud cover at 16:00 and estimated its arrival at the Salamanca JW radio beacon for 16:50.
At 16:54, the pilot notified Madrid D.F. station that the aircraft had passed Salamanca at 16:50 while maintaining flight level 95. During this communication, the crew reported that their VHF equipment was malfunctioning and requested to use an alternative frequency of 3 023.5 kc/s to contact Barajas Tower.
Madrid control subsequently cleared the aircraft to proceed directly toward the Barajas radio range at flight level 95 and authorized the frequency change at 17:15. This was the final communication received from the flight. Between 17:15 and 17:20, the aircraft type impacted the peak of La Rodilla de la Mujer Muerta, which sits at an elevation of 1,999 metres. The impact occurred approximately 800 metres below the assigned flight level, causing the aircraft to burst into flames. There were 21 fatalities and no survivors.
Findings
Investigators considered that if meteorological conditions were the primary driver, severe icing was the most likely factor. It is theorized that the aircraft may have encountered cumulus congestus clouds, leading to rapid ice accumulation. This could have caused a sudden change in aerodynamic properties resulting in an unrecoverable stall, or led to a rapid loss of altitude into turbulent downdrafts near the mountain lee slope.
Additionally, it is possible the pilot may have descended below the freezing level—estimated at 2,200 metres—under the mistaken impression that the mountain divide had already been cleared. While another flight had passed the same area 40 minutes earlier without incident, the possibility of sudden, severe icing conditions remains a primary consideration.