The Air France DC-4, named “Ciel de Savoie”, landed at Douala at 12:00 and after refueling took off at 14:08 on the leg to Niamey, Niger. This leg was part of the Air France service between Brazzaville, Congo and Paris. The flight plan indicated that the pilot intended to take the southern route to Niamey, avoiding higher terrain, with an en route altitude of 8500 feet. Some four minutes after takeoff the flight made a sharp climbing turn heading NNW, on a straight course to Niamey over the British Cameroon mountains. The plane possibly drifted towards higher terrain until it was heading for Cameroon Mountain (elevation: 13,354 feet). The crew were facing the sun. Seen through the mist the mountain was probably only partially or faintly visible. They probably saw the mountain until it was too late to climb over it. The pilot immediately made a sharp left turn but the plane hit the steeply rising terrain with the left wing. The aircraft then impacted the mountain at an altitude of about 8500 feet. PROBABLE CAUSE: “On their own initiative the crew abandoned the current procedure and followed a different and inaccurate procedure. The navigation was not sufficiently accurate and the draft was not checked. Error of judgement and over-confidence when flying over mountain mass. “