What happened
A scheduled international passenger service was operating a multi-leg itinerary including stops in Paris, Marseube, Palma de Mallorca, and Port-Etienne. After an unremarkable flight to Palma, the aircraft departed from runway 27 bound for Port-Etienne at 0314 hours GMT, following an assessment of current weather conditions.
The flight plan required the crew to coordinate with several air traffic control centers, including Barcelona, Seville, Casablanca, and Dakar, as well as the tower at Port-Etienne. At 0339 hours, the crew notified Palma control that they were positioned over Ibiza. By 0401 hours, the aircraft had transitioned into the Barcelona FIR at flight level 100. Earlier communications with Seville FIR indicated an estimated crossing of the boundary at 0401 hours and a planned arrival near Los Alcazares at 0415 hours.
At 0420 hours, the crew reported passing Los Alcazares under clear weather conditions. They provided further estimates for passing abeam Malaga at 0500 hours, overhead Tanger at 0524 hours, and reaching Port-Etienne at 1020 hours. This transmission marked the final contact with the aircraft. Subsequent attempts by Seville FIR to re-establish communication were unsuccessful. The aircraft subsequently struck a mountain at 0445 hours.
Findings
Investigations revealed that while the aircraft was flying in clear skies, it had departed from its intended flight path. Although the aircraft remained at altitudes within established safety parameters, the actual route taken after passing Los Alcazares differed significantly from the planned trajectory. The deviation between the intended route toward Tanger and the actual path of the aircraft exceeded 5 degrees. While autopilot precision is typically within a 1-degree margin, investigators noted that wind or an unidentified error could account for the remaining 4-degree discrepancy.