The Accident Investigation Bureau (AIB) in its preliminary report of the Associated Airlines plane crash at Lagos airport last week says pilot error and a faulty engine might have been responsible for the crash, but the bureau said it was yet to conclude investigations on the crash.
The report says investigations unveiled hints that the aircraft was already faulty before the cockpit crew decided to embark on the journey but the captain in command, Capt. Abdulraham Yakubu insisted that the crew must continue with the journey even when the co-pilot suggested that the flight should be aborted.
The aircraft crashed exactly 31 seconds after take off from the runway.
According to Muktar Usman, Commissioner of AIB, who is also an aircraft pilot, before the crew embarked on the flight, the crew received an automated warning from the onboard computer voice, which consisted of three chimes followed by “Take-off Flaps…Take-off Flaps,” which were repeated severally.
Usman said that the warning suggested that the flaps were not in the correct position for take-off and there is some evidence that the crew may have chosen not to use flaps for the take-off.
He however said that the warning did not appear to come as any surprise to the crew who continued with the take-off.
“This warning continues throughout the take-off roll. As we are in the process of verifying the accuracy of the flight data, we have not yet been able to confirm the actual flap setting. However, we expect to determine this in the fullness of time.
“It was determined from the Cockpit Voice Recorder, CVR, that the pilot flying was the captain and the pilot monitoring and assisting was the First Officer.”
Usman explained further that at a particular point, a ‘set power’ call was made by the captain and the ‘power is set’ call was confirmed by the First Officer as expected in normal operations.
He continued that approximately three seconds after the ‘power is set’ call, the First Officer noted that the aircraft was moving slowly, adding that approximately seven seconds after the ‘power is set’ call, the internal aircraft voice warning system could be heard stating, ‘Take off Flaps, Auto Feather.’
He emphasised that at this time, AIB could confirm that the right engine appeared to be producing considerably less thrust than the left engine, which appeared to be working normally, reiterating that the automated voice continued to repeat ‘Take-off Flaps, Auto Feather.’
At a point, he explained that the standard ‘eighty knots’ call was made by the First Officer, which evidenced that there was a problem with the take off roll.
This he said made the co-pilot ask if the take-off could be aborted to which the Captain disagreed and insisted that they should continue with the flight.
Besides, he added that the crew did not make a ‘V1′ call, which is the speed at which a decision to abort or continue a take-off is made.
“During the rotation, the First Officer stated ‘gently’, which we believe reflects concern that the aircraft is not performing normally and therefore needs to be rotated very gently so as not to aerodynamically stall the aircraft.
“The First Officer indicated that the aircraft was not climbing and advised the captain who was flying not to stall the aircraft. Higher climb angles can cause an aerodynamics stall. If the aircraft is not producing enough overall thrust, it is difficult or impossible to climb without the risk of an aerodynamic stall.
“Immediately after lift-off, the aircraft slowly veered off the runway heading to the right and was not climbing properly. This aircraft behaviour appears to have resulted in the Air Traffic Controller asking flight 361 if operation was normal. Flight 361 never responded.”
Usman explained that the AIB was focussing its investigations on mechanical and electronic engine control issues related to the right engine and right engine propeller systems.
He however emphasised that the bureau had not made any safety recommendations on the crash, but said it would not wait for the final report to issue safety recommendations “should any issue arise that we feel need immediate attention.”
The crash, it would be recalled, killed 13 persons two weeks ago.
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