Event Details
On the day of the accident, an aircraft was conducting a charter operation for the Central Bank of Nigeria. The flight originated from Lagos, with the first segment (Lagos to Abuja) flown by the Commander. After a brief power-setting issue on the starboard engine during cruise, the flight continued normally to Abuja. The aircraft then departed Abuja for Jos at 0900 hours UTC, carrying six souls on board and with five hours of endurance, with the First Officer at the controls.
Flight Sequence
At FL 90, approximately 30 nautical miles from Abuja, the crew again encountered problems with the cruise power setting on the starboard engine, with torque remaining at 1400. The crew retarded the right power lever to the minimum to achieve a cruise setting of 1300, but the gear warning activated. The Commander then took over the controls. At 0923 hours UTC, the aircraft contacted Kaduna Tower, reporting a diversion to Kaduna, its flight level as 90, distance 61 miles, and estimated TMA at 24 miles, with 'KC' at 41 miles. The tower issued an inbound clearance to the 'KC' locator, maintaining FL 90, with no delay expected for a locator approach to runway 05. Weather at 0900 hours was passed: wind 090/05 knots, QNH 1014, temperature 30°C.
At 0928 hours UTC, the airplane, at about 42 miles and speed between 150-160 knots, requested descent and was cleared to 4,500 feet, QNH 1014. At about 0935 hours UTC, the pilots informed the tower that they would make a single-engine approach due to problems controlling power on the starboard engine, which they would shut down. The tower asked if fire coverage was needed; the pilots affirmed. The Commander reviewed the single-engine approach with the First Officer, estimating 4,500 feet at 8 NM. Approaching 4,500 feet at 11 NM, the crew shut down the right engine, after which speed decayed from 150 to 140 knots.
Final Approach
At 0946 hours UTC, the pilot reported 6 NM final and the field in sight; the tower requested a report at 4 NM final. Shortly, the controller reported having the aircraft in sight and cleared it to land on runway 05, with wind north easterly at 6 knots. Descending at 500 feet per minute, the Commander requested 25% flap, but the First Officer selected full flap. Speed began decaying and bleeding faster. When the aircraft was at 2,700 feet, speed had decayed to between 100-110 knots. The crew applied full power on the port engine to arrest the decay, but to no avail. The pilot was attempting to correct the descent rate, speed decay, and asymmetry when the stall warning activated. All efforts by the controller to establish further contact proved abortive. The controller observed a gust of dust, indicating the aircraft had crashed.
Probable Cause and Findings
The aircraft crashed into the new VOR/DME site being constructed, about 1175 meters from the threshold of runway 05, at 0947 hours UTC. The final resting position was about 68 meters from the first point of impact, with the aircraft turned nearly 180° from its initial flight path.
The official investigation stated the probable cause as the poor handling by the crew of the one-engine inoperative approach. Findings included: the aircraft was properly registered and certified; the Commander was certified, but the First Officer lacked a valid licence; the proficiency check did not include critical manoeuvres like simulated single-engine approach and stalls; the crew informed the tower they would make a single-engine approach; they did not adhere to laid-down procedures for such an approach; crew coordination was lacking; the landing configuration was full flaps, gear up, with power only on the port engine; the starboard engine propeller was not feathered; and the aircraft crashed into the new VOR/DME site. Power was present on the port engine, evidenced by severe flexural damage to the propeller blades.