Khartoum

Wrong approach configuration on part of the flying crew who continued the approach below minima weather conditions and passed the minimum descent altitude without any visual contact with the ground or runway. In such conditions, the captain should make a go-around procedure.

Due to the lack of conclusive evidence it is not possible to formulate an opinion as to the direct cause of the accident. From the evidence available it is possible that one or more of the following items could have contributed tot the cause of the accident:
- No satisfactory reason has yet been put forward for the initial turn of the aircraft to the port,
- The loss of height after the turn was probably caused by the selection of the flaps from 1/4 position to the 'UP' position,
- From witness' statement it would appear that at some time after the aircraft was starting to re-commence climbing on one or both of the engines 'coughed'. This could have been caused by the inadvertent mishandling of either the throttle and/or mixture control levers by the pilot under training as he left his seat. The possibility also exists that he may have pulled himself up by the ignition master switch, at the same time inadvertently switching 'off' the port ignition switch. (evidence of an explosion in the port exhaust system could have been caused by either of the above events,
- If anything like the possibility mentioned in item 3) did in fact occur it would have been just at the critical time when the Training captain was re-gaining control of the aircraft, and could have presented him with a situation from which it was impossible to recover, bearing in mind the proximity of obstructions and the fact that he was alone in the cockpit.

It is believed the accident was caused by a premature descent on part of the crew.

It was determined that the failure of the support member for the starboard main gear uplock caused the gear to fall in flight, damaging hydraulic system lines.

It was determined that the accident was the consequence of the combination of the following factors:
- The fact that the aircraft progressed actually at an average ground speed of at least 200-205 knots while the crew believed they were proceeding with no more than 175-178 knots as estimated before takeoff,
- That a slight directional difference of 2 or 3 degrees may have existed between the calculated track and the actual flight path,
- That these two navigation inaccuracies could build up during a flight of 2,5 hours and could eventually result in a position error of about 70 NM to the west and about 30 NM to the south,
- That for reasons unknown to the Board the position report given for 1906Z and apparently established on the base of an astronomical fix must have been inaccurate and that the crew were, therefore, not able to be conscious of the discrepancies between the dead-reckoning and their actual position,
- That the aircraft flying at 8000 feet hit a slope of the Djebel Marra mountains four minutes before the crew expected to be overhead the El Fasher beacon where they would have begun the climb to 12000 feet and when, in their belief the aircraft should have been still more than 60 NM away from these mountains.