The flight left London Gatwick at 20:43 UTC on 6 October 1961 destined for Perpignan in the south of France, just north of the Pyrenees.

In an area of intermittent rain and winds of variable force, it struck the side of Le Canigou at an altitude of 7500 ft (2200 m).

[4] However, the official inquiry concluded that "the accident was attributed to navigational error, the origin of which it was not possible to determine for lack of sufficient evidence.

"[5] The French inquiry found that the aircraft was flying at a height "below the safety altitude obtained from the correct application to the Toulouse – Perpignan route of the general instructions contained in the operations manual of Derby Aviation."

The charts that may have been on board the aircraft, says the report, could have led to the calculation, on account of lack of uniformity in the heights presented, of differing safety altitudes.

Although this reconstruction, says the report, seems to offer a perfectly acceptable solution in the absence of evidence to the contrary, including precise information of the kind which could be provided by a flight recorder, the commission could not consider it as definitive.

The co-pilot, 1st Officer Rex Hailstone (2,267 hours) had made five landings at Perpignan in the previous six months, though not on routes via Toulouse.