What happened
A flight departing from Lyon for Clermont-Ferrand encountered severe weather conditions, including heavy rain, turbulence, icing, and low ceilings due to storm activity. After receiving clearance to descend to 3,600 feet for an ILS approach, the four-engine airplane entered thick cloud cover. During this phase, the aircraft struck trees and crashed upside down on the Pic du Picot in the Forez Mountain Range. The wreckage was located in the Faye forest approximately seven hours after the impact. While eight passengers were successfully evacuated, the accident resulted in 60 fatalities.
Findings
The investigation concluded that the accident was a controlled flight into terrain. The crew had deviated approximately 30 km to the east of their intended path while believing they were positioned directly over Clermont-Ferrand. This error was attributed to a significant malfunction or erroneous reading of the radiocompass, which provided false directional information. Investigators noted that the crew may have relied too heavily on these faulty indications and failed to notice that their timing was inconsistent with the expected arrival at the beacon.
Two primary anomalies were identified regarding the navigation errors. First, the radiocompass indicated they were over the destination when they were actually far away; this may have been caused by an antenna fault or localized electrical discharges from intense precipitation acting as a false transmitter. Second, the crew failed to notice a significant discrepancy in their estimated arrival time. Factors such as heavy turbulence, the presence of an instructor pilot, and potential visual distractions like city lights may have contributed to the crew's failure to cross-check their position using alternative navigation methods.