Flight Details
The aircraft departed Abuja with call sign SXC401 en route to Port Harcourt, carrying two passengers on a revenue basis. Before the flight, the chief engineer replaced the carbon brush of the starboard starter generator; the source of the replacement carbon brushes was questionable. The flight to Port Harcourt was uneventful. After the passengers disembarked, the aircraft refueled for the onward journey to Calabar.
The aircraft departed Port Harcourt at 1750 hours UTC with five souls on board, all crew members, estimating arrival at Calabar at 1827 hours UTC.
Accident Sequence
At 1800 hours UTC, the aircraft contacted Calabar Tower at 5,000 feet, reporting five souls on board and an endurance of 3 hours 30 minutes. The crew requested the hourly weather report; the tower passed the 1700 hours weather: surface wind 140°/09 knots, visibility 10 km, slight thunderstorm, cloud base scattered 300 metres, few CB N-SE 690 m broken at 9,000 m, QNH 1008, temperature 27°C. The aircraft was instructed to maintain 5,000 feet and expect no delay for the VOR approach to runway 03.
At 1809 hours UTC, the aircraft was 35 nautical miles from the station when the pilot requested descent clearance; the controller cleared the aircraft to 2,500 feet and to position for a straight-in approach to runway 03, which the crew acknowledged.
At 1824 hours UTC, the pilot reported an electrical problem and declared an emergency. The pilot requested increased intensity of the approach lights; the controller stated the lights were already at maximum intensity. The controller then asked for the aircraft's altitude; the pilot responded, "we are coming to Calabar." At 1830 hours UTC, the aircraft reported 16 nautical miles from Calabar. At 1833 hours UTC, the controller repeatedly asked for the aircraft's position, receiving the response "standby, standby." Verbal queries continued until 1842 hours UTC, after which there was no further response. The controller alerted the airport fire services and later contacted relevant agencies for search and rescue.
Meanwhile, the aircraft on descent impacted trees and crashed in a marshy area 22 km from the airport. The aircraft was destroyed, and all five occupants were killed.
Investigation
The investigation determined that the aircraft prematurely descended below the normal Minimum Safe Altitude of 2,500 feet without ATC clearance until it flew into terrain. Contributory factors included an electrical problem that may have distracted pilots from focusing on instruments, and unfavorable weather conditions (low cloud base and thunderstorm) that impaired visibility during descent.