The Accident Investigation Bureau (AIB) has released the preliminary report on an Associated Airlines plane that crashed nine days ago shortly after take-off from the Muritala Muhammed International Airport, Lagos, killing 15 persons.
Briefing newsmen on Friday, the Head of AIB, Usman Mukthar, said the analysis of flight 361 recorder showed that the pilot flew the aircraft with a faulty right engine.
Muktar said the wind was calm as at the time the flight 361 was cleared for take-off by the Air Traffic Controller on runway 18 left of the Murtala Muhammed Airport (MMA) Lagos.
However, about four seconds after engine power was advanced to commence take-off roll, Muktar said the crew received an automated warning from the on-board computer voice which consisted of three chimes followed by ‘Take-off Flap, Take-off Flap, Take-off Flap”. This he explained suggested that the flaps were not in good order for take-off.
But surprisingly, the pilot of the ill-fated aircraft, Abdulrahman Yakubu ignored the warning from the on-board computer voice.
The Commissioner for AIB said experts from Canada assisted the Bureau the readout and analysis process, adding that the investigation is being conducted in accordance with the provisions of International Civil Aviation Organization (ICAO) Annex 13, of which Nigeria is a member State.
Muktar said, “The flight data recorder or FDR contained approximately 47 hours of data in solid state memory. The recorder downloaded without issue. There were approximately 50 parameters recorded. A few parameters were not working properly however we do not think, in this particular case, that it will hamper the overall investigation.
“The cockpit voice recorder or CVR was an older generation magnetic tape based device. The CVR’s magnetic tape recording was removed from the unit and replayed on an open reel 4 track tape deck specially adapted for replaying CVR’s of this type. The CVR contained 32 and one half minutes of audio which included the internal conversation of the two pilots, radio calls and the overall aural environment in the cockpit on the cockpit area microphone.
“The CVR was of good quality and the team is in the process of generating a complete transcript of all relevant information. The AIB plans to release the transcript as part of its final report of the accident however the actual recording is, under international protocol, sensitive and therefore privileged information and will not be released at any time.
“Associated 361 was cleared for take-off on runway one eight left at Lagos international airport. The wind was calm and weather is not considered a factor in this accident. Approximately 4 seconds after engine power was advanced to commence the take-off roll, the crew received an automated warning from the onboard computer voice which consisted of three chimes followed by “Take-off Flaps…Take-off Flaps”.
“This is a configuration warning that suggests 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. The warning did not appear to come as any surprise to the crew and they continued normally with the take-off. This warning continues throughout the take-off roll.
“In the feather position, the propeller does not produce any thrust. The FDR 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 continued to repeat ‘Take-off Flaps, Auto Feather’.
“Immediately after lift-off, the aircraft slowly veered off the runway heading to the right and was not climbing properly. This aircraft behavior appears to have resulted in the Air Traffic Controller asking Flight 361 if operation was normal. Flight 361 never responded.
“Less than 10 seconds after rotation of the aircraft to climb away from the runway, the stall warning sounded in the cockpit and continued to the end of the recording. The flight data shows characteristics consistent with an aerodynamic stall.
31 seconds after the stall warning was heard, the aircraft impacted the ground in a nose down near 90 degree right bank”.
