Preliminary
readout and analysis by the Accident Investigation Bureau on the
Associated Airlines plane that crashed in Lagos on October 3, 2013, has
revealed that the crash was due to human error and the failure of one of
the engines of the aircraft.
The Commissioner/Chief Executive
Officer, AIB, Capt. Muhtar Usman, stated in Abuja on Friday that a
preliminary analysis of the Cockpit Voice Recorder indicated that the
crew received an automated warning that suggested that the aircraft
flaps and the right engine were not in order for take –off but the
pilots ignored the warning.
Usman said, “Approximately four 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 correct position for take-off and
there is some evidence that the crew may have chosen not to use flaps
for take-off.”
Addressing journalists at the
headquarters of the bureau on the outcome of the preliminary analysis on
the CVR, Usman explained that it was evidenced that the crew, prior to
departure, discussed some concerns about the plane.
But despite the concerns, the AIB CEO
said the crew still flew the aircraft. The plane was conveying the
corpse of the late former governor of Ondo State, Mr. Olusegun Agagu, to
Akure. The plane eventually crashed and 16 persons including the pilot
and First Officer died.
Usman said the warning continued
throughout the take-off roll. He explained that the bureau was in the
process of verifying the accuracy of the flight data and was yet to
confirm the actual flap setting, but would do so in fullness of time.
He noted that the pilots ignored the
warning, stressing that “it did not appear to come as any surprise to
the crew,” as they continued normally with take-off.
The AIB boss said it was determined from
the CVR that the pilot who flew the plane was the captain, while the
pilot who monitored and assisted was the First Officer.
He said, “The ‘set power’ call was made
by the captain and the ‘power is set’ call was confirmed by the First
Officer as expected in the normal operations. Approximately three
seconds after the ‘power is set’ call, the First Officer noted that the
aircraft was moving slowly.”
He added 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’.
Auto Feather refers to the pitch of the propeller blades. In the feather position, the propeller does not produce any thrust.
Usman said, “The Flight Data Recorder
contains several engine related parameters which the AIB is studying. At
this point, 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’. The physical examination of
the wreckage revealed that the right engine propeller was in the feather
position and the engine fire handle was pulled/activated.”
Usman stated that the wind was calm and
weather was not considered a factor for the accident after the plane was
cleared for take-off on runway one eight left at the Lagos
international airport.
He said the standard call to show that
there was problem as the flight was taking off was made by the First
Officer. The call was not heeded by the captain.
He said, “The standard ‘eighty knot’
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.
“In response to the First Officer’s
question to abort, the Captain indicated that they should continue and
they continued the take-off roll. The crew did not make ‘V1’ call or a
Vr call.”
V1 call, according to the bureau chief,
is the speed at which a decision to abort or continue a take-off is
made, while Vr is the speed at which it is planned to rotate the
aircraft.
He stated that normally, the non-flying pilot calls both the V1 and Vr speeds.
He said, “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.”
Usman said higher climb angles could
cause an aerodynamic stall. He stated that if the aircraft was not
producing enough overall thrust, it would be difficult or impossible to
climb without the risk of an aerodynamic stall.
He said, “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.
“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 was heard, the aircraft impacted the ground in a nose
down near 90 degree right bank.”
Usman outlined the concerns to be
investigated by the bureau to include mechanical and electronic engine
control issues related to the right engine and its propeller systems,
aural warnings related to auto-feather and the flap settings required
for takeoff, and take-off configuration issues with respect to flap
settings.
Others are crew decision making and
training with respect to continuing the take-off roll despite continuous
automated voice warnings of both ‘take-off flaps’ and ‘auto feather’
when there was ample time to abort take-off, and the airline’s
management safety culture fostered throughout the airline.
When contacted, the spokesman for the
Associated Airline, Mr. Alex Emodi, said the officials of the carrier
were holding a meeting on the issue.
He said the carrier would respond after
the meeting. As at 10 pm when one of our correspondents called, the
spokesman said the meeting had yet to be concluded.
However, aviation experts have expressed mixed reactions over the preliminary report.
The Chief Executive Officer, Centurion
Aviation Safety & Security Consult, Captain John Ojikutu, said that
when such an accident happened, so many factors needed to be considered.
According to him, the state of mind of
the pilot in question has to be considered before conclusions are drawn
on why he didn’t heed the warnings on the aircraft cockpit.
He said, “There are so many things you
have to think of -the psychological and physiological state of mind of
the pilot in question, and there are pertinent questions that must be
asked at this point in time. For instance, when last did the pilot in
question fly? Had he been familiarising himself with the simulation
checks he was supposed to be involved in as a pilot? There are some
checks that pilots are supposed to undertake to know what to do in
certain circumstances, had he done these?
“I hope you are aware that some of these
pilots have not been paid salaries for some time, and so, if that was
the case with him for instance, it is possible he was not
concentrating.’’
The President, Aviation Roundtable,
Captain Dele Ore, expressed doubt over the outcome of the report, saying
the AIB needed to expedite action on the final report.
He said, “Well, in my opinion, I do not
believe in the objectivity of that report, what evidence do they have?
Is it in the CVR? If it is in the CVR, I cannot visualise the kind of
warning they could have received from just that, except they really come
out with the Flight Data Recorder decoded.
“The fact remains that I am not
impressed that we always want to put the blame on somebody and in this
case someone who is no longer here to defend himself, and I stand to
defend the person who cannot defend himself. The regulators should give
out information that Nigerians can believe, because as far as I am
concerned, they are looking in the wrong direction.”
Also, Aviation analyst and Head,
Research and Statistics, Zenith Aviation, Mr. Olumide Ohunayo, said
although the preliminary report had shown that the tragic crash might
have been caused by human error, the Accident Investigation Bureau
needed to expedite the investigation to unravel other causes of the
crash.
Ohunayo said, “It is human error from
the preliminary report, because the equipment gave all the necessary
warning. Now the next question is why was the pilot eager to operate
despite the warnings? Was he under economic or managerial pressure to
operate that flight? The aircraft had been on ground for a long time;
did the management conduct the necessary checks and necessary approvals
for that aircraft to operate a revenue flight?
“If the aircraft was in good condition
why were they having seven of their staff on board a small aircraft
operating for revenue? Answers are needed to unravel this fatal riddle.”
The analyst also urged the government to
make its ‘non-punitive reporting system’ effective such that it would
be easier for pilots and other professionals to report any perceived
danger in the system.
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