The Lion Air plane that crashed into the sea last month killing 189 people was not airworthy and should have been grounded, according to Indonesian investigators.
Indonesia’s transport safety committee (KNKT) released a preliminary report revealing fresh details of the pilot’s efforts to steady the jet, including his last words to air traffic control, asking to be cleared to 5,000 feet.
The report focused on the airline’s maintenance practices and Boeing’s new anti-stall systems that prevent the plane from going upwards at too high an angle where it could lose its lift, commonly known as the angle-of-attack sensor (AOA).
During the fatal flight, however, the anti-stall system continuously forced the plane’s nose down, even when it was not stalling possibly due to a faulty sensor, according to the report.
The pilots reportedly engaged in a futile tug-of-war with the sensor, trying to correct the fault by pointing the nose higher, which happened around 20 times.
KNKT’s findings suggest the airline put the plane back into service despite it having issues with the sensor on its second-to-last flight.
In the previous instance, the pilots were able to overcome the issue by disabling the sensor.
But investigators said it is unclear why the pilots in the plane’s last flight didn’t follow the same procedure.
The aviation head at the KNKT, Nurcahyo Utomo said it was “too early to conclude” if the AOA sensor has contributed to the crash, according to the BBC.
“In our opinion, the plane was no longer airworthy and it should not have continued,” he said.
The report also advised Lion Air’s safety culture should be improved and it should ensure operations manuals are followed.
Lion Air has rejected claims the airline’s Boeing 737 had not been airworthy since the flight before the crash, according to Fairfax.
“I think pilots can judge for themselves whether to continue,” said Lion Air managing director Daniel Putut.
Featured image source: Reuters