Barely 10 days after 15 of the 20 persons on board the Associated Airlines Embraer 120 aircraft died when the plane crashed at the Murtala Muhammed Airport (MMA), Lagos, the Accident Investigation Bureau (AIB) on Friday said that the preliminary readout and analysis of flight 361 flight recorder indicated that the right engine of the aircraft was faulty.
The agency also said that preliminary investigation indicated that the captain- in-command of the ill-fated aircraft, Capt Abdulrahman Yakubu ignore the warning from the on-board computer voice.
This was disclosed to journalists by the Commissioner for AIB, Capt Usman Mukthar, while reading out the preliminary readout and analysis of flight 361’s flight recorders in Abuja.
He said that the investigation was done in AIB laboratory in Abuja in conjunction with international flight recorder experts from Canada, who designed the laboratory.
Capt Mukthar said that the Flight Data Recorder (FDR) contains approximately 47 hours in solid state memory, while the Cockpit Voice Recorder (CVR) contained 32 and half minutes of audio, which included internal conversation of two pilots, radio calls, and the overall aural environment in the cockpit.
Muktar said that Associated Airlines flight 361 was cleared for take-off by the Air Traffic Controller on runway 18 left of the Murtala Muhammed Airport (MMA) Lagos, adding that at that time the wind was calm and weather was not considered a factor in the accident.
He added that four seconds after engine power was advanced to commence take-off roll, the crew received an automated warning from the on-board computer voice which consisted of three chimes followed by according to him, ‘Take-off Flap, Take-off Flap, Take-off Flap”.
He stated that this configuration warning suggests that the flaps were not in the correct position for take-off and there is some evidence that the crew may not have chosen not to use flaps for the take-off.
According to him, “This warning did not appear to come as any surprise to the crew and they continued normally with the takeoff .This warning continued throughout the take-off roll “
Capt Mukhtar added that AIB was in the process of verifying the accuracy of the flight data, adding that the agency has not been able to confirm the actual flap setting and that AIB is however expected to determine this in the fullness of time.
The AIB commissioner added that the ‘set power’ call was made by the captain and the ‘power is set’ was confirmed by the First Officer as expected in the normal operations, adding that approximately three seconds after the ‘power is set’ call, the First officer noted that the aircraft was moving slowly.
Approximately seven seconds after the ‘power is set ‘call, the internal aircraft voice warning system could be heard stating ‘Take-off Flap’, Auto Feather.
He explained that Auto Feather refers to the pitch of the propeller blades, adding that in the feather position, the propeller does not produce any thrust.
The Flight Data Recorder, he said contains several engine related parameters, which the AIB is studying.
“At this time, we can state that the right engine appears to be producing considerably less thrust than the left engine. The left engine appeared to be working normally .The aircraft automated voice contained to repeat, Take-off Flap, Auto-Feather’
Reading out the preliminary report, AIB said, that the “Standard ‘eighty knots’ call was made by the First Officer .The first evidence that the crew indicated that there was a problem with the take-off roll was immediately following the ‘eighty knots’ call. The First Officer asked if the take-off should be aborted approximately 12 seconds after the ‘eighty knots’ callout”
AIB added that the Capt in response to the Flight Officer’s question to abort the take off, said that they should continue, adding that the crew did not make ‘V1′ call which is the speed at which the decision to abort or continue a take-off is made or the ‘Vr’ call, which indicate the speed at which it is planned to rotate the aircraft.
The Commissioner added that normally the non flying pilot pulls back both the V1 and the Vr speeds.
He said that when the Vr was called the flying pilot pulled back the control column, the First Officer asked the Captain ‘gently’, a word that indicated that the aircraft was not performing normally.
He added that the aircraft did not produce enough overall thrust and that it was difficult or impossible to climb without risk of an aerodynamics stall.
Immediately after lift-off , the aircraft slowly veered off the runway heading the to the right and was not climbing, and that the aircraft behaviour made ATC to ask the pilot if Flight 361operation was normal but that they did not respond and that the plane crashed 31 seconds after the stall warning.
