The Accident Investigation Bureau (AIB) has
revealed that the October 3rd Associated
Airlines crash that killed 14 people was caused
by pilot error. The agency explained that the
preliminary readout and analysis of the 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, Abdulrahman
Yakubu, ignored the warning from the onboard
computer voice.
This was disclosed to journalists by the
Commissioner for AIB, Capt. Usman Muktar,
while reading out the preliminary readout and
analysis of flight 361’s flight recorders in Abuja
yesterday.
He said 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 the Flight Data Recorder
(FDR) contained approximately 47 hours in solid
state memory, while the Cockpit Voice Recorder
(CVR) contained thirty-two and a half minutes of
audio, which included internal conversation of
two pilots, radio calls, and the overall
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 the engine
power was advanced to commence take off roll,
the crew received an automated warning from
the onboard computer voice which consisted of
three chimes followed by “Take off Flap, Take off
Flap, Take off flap.”
He stated that this configuration warning
suggested that the flaps were not in the correct
position for take-off and there was evidence that
the crew might 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 take-off. This
warning continues 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 had not been able
to confirm the actual flap setting and that AIB
was 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 was 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 Flap, Auto
Feather.’ “
According to an aircraft engineer, Sheri Kyari,
the flap on an aircraft is located at the trailing
edge of the wing. It is at the rear end of the
wings.
Kyari, a former president of Pilots and Aircraft
Engineers in the defunct Nigeria Airways Limited,
the function of the flap when operational
increases the surface area of the wing, thereby
generating enough lift at low aircraft speeds.
This is when the aircraft is taking off or landing.
Kyari, is convener and executive director, Centre
of Aviation Safety and Research.
“When the flap is not set to the required degree
for take off, the aircraft will have to do a long
take-off run before gaining enough lift to lift-off
the ground,” he said.
Reading out the preliminary report, AIB said “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 captain, 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 indicates 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.
An aviation expert, Mallam Muhammadu Dodo,
described aerodynamics as the streamline of air
flow around the aircraft due to its design. It
enables it to attain a stable and safe flight.
Immediately after lift-off, the aircraft slowly
veered off the runway, heading to the right and
was not climbing, and that the aircraft behaviour
made ATC to ask the pilot if Flight 361 operation
was normal but that they did not respond, and
that 31 seconds after the warning, the aircraft
crashed.
Culled from The Nation
