Accident Overview
On July 11, an aircraft departed Zurich at 2043 local time. The en route portion of the flight was uneventful. At 01:00, the flight contacted Sale Tower and requested weather information. The tower reported visibility 10 meters (30 feet) with ground fog and clear sky. The flight then advised it was heading for Casablanca, the alternate airport.
Approach and Descent
At 01:06, the aircraft gave its position as 5 miles from Casablanca-Anfa (CAS), requested permission to descend, and asked for landing instructions. The tower requested a call when on the downwind leg. Four minutes later, the flight was asked to call when on final approach and was told it was number one for landing, with surface wind 040° at 4 knots. The pilot replied that he would call when over the range station.
Weather and Final Communications
The aircraft flew over the field at 01:13. Three minutes later, the pilot reported an altitude of 400 meters (1,300 feet) and a ceiling of 150 meters (500 feet). The tower advised that cloud cover was 7/8 with a ceiling of 140-150 meters (450-500 feet). Three minutes later, conditions were reported as 7/8 with a ceiling of 100 meters (330 feet).
At 01:22, the aircraft requested permission to land at Casablanca-Nouasseur Airport (CMN) if possible; the tower asked him to wait. Two minutes later, the aircraft was asked about remaining fuel and replied it had enough for 90 minutes. While Anfa control was transmitting this request to American authorities in Nouasseur, the aircraft crashed at 01:25, in line with runway 03 about 8 miles from its threshold.
Investigation Findings
The official investigating commission considered assumptions including material failure, electrical failure, abrupt maneuver to avoid another aircraft, and unfavorable weather conditions. None satisfied the commission as being a definite cause of the accident. The commission noted that unfavorable weather, although unlikely at first sight, could account for the accident if the crew, warned of deteriorating weather by the Anfa tower, had decided to take advantage of partial visibility between stratus clouds and attempted a fast let-down in unfavorable conditions.