Flight SN712 Accident: Cargo Flight from Brussels to Lagos (OO-SJK)

Flight Details and Initial Approach Flight SN712 was a non-scheduled international cargo flight operating from Brussels to Lagos on behalf of the Federal Government of Nigeria. The aircraft carried 34,994 kg of cargo and no passengers. It departed Brussels at 2152 GMT on 12 July 1968, with a filed flight plan for 6 hours 9 minutes and a stated total endurance of 8 hours 20 minutes. Kano was designated as the alternate. Routine radio reports were received during the en route phase. At 0325 GMT, the aircraft contacted Lagos approach control. The transmissions were identified as almost certainly being made by the co-pilot while the pilot-in-command flew the aircraft. The flight reported an estimated time of arrival at Lagos of 0355 GMT at flight level 330. Lagos weather information included a wind of 210° at 3 kt, visibility of 16 km, 5/8 stratocumulus at 270 m, 7/8 altostratus at 2,400 m, temporary thunderstorms, 118 cumulonimbus at 2,000 ft, QNH 1012 mb, and a temperature of 24°. ## Descent and Approach Sequence At 0327 GMT, the aircraft reported an estimated time overhead Ibadan NDB of 0344 GMT. One minute later, it reported that the Ibadan NDB did not appear to be operating. At 0336 GMT, the aircraft requested and received descent clearance to Lagos at flight level 60, commencing descent from flight level 330. Three minutes later, it reported passing Ibadan and descending through flight level 275, although its position determination was unclear given the earlier report of the inoperative NDB. Lagos approach stated there was no delay and that runway 19 was in use. At 0341 GMT, approximately 50 miles north of Lagos, the aircraft was recleared to 2,200 ft on QNH 1012 mb and instructed to report the field in sight. Flight recorder data showed the descent was briefly interrupted as speed decreased to the recommended maximum for landing gear extension, a speed not exceeded thereafter. The automatic pilot was most probably disengaged at this stage. The rate of descent was then re-established to approximately 2,000 ft/min. At 0350 GMT, the aircraft passed one mile east of Lagos airport on a southerly heading at 15,000 ft. A procedure turn was made south of the airport, followed by a second descent interruption after which airspeed remained below the maximum for 25° of flap. At 0354 GMT, the aircraft passed over the airport northbound at 9,000 ft, maintaining an average descent rate of 2,000 ft/min for another 2.5 minutes. At 0356 GMT, a final procedure turn began at about 5,000 ft, with the descent rate reduced to 1,500 ft/min. The track between the northbound passage and the final procedure turn closely matched the outbound track of the published VOR approach procedure. ## Final Moments and Impact At 0357 GMT, the aircraft informed Lagos approach it was in the procedure turn and requested wind conditions. Control reported the wind was calm, which was acknowledged. Approach control then instructed the aircraft to report the runway in sight, which was also acknowledged. On completion of the procedure turn at 1,400 ft (1,268 ft above the airport), airspeed was reduced from 190 kt to just under 160 kt, and the descent rate decreased to 900 ft/min. The heading stabilized on 197° magnetic. At 0359 GMT, the aircraft requested maximum runway light brightness. Approach control replied that the runway lights were on low intensity non-variable. A transmitter switch was heard, but no further message was received before the aircraft crashed approximately 8.5 miles north of the airport, roughly on the extended centerline of the runway. All seven occupants were killed, and the aircraft caught fire immediately and was burnt out.