Indonesian researchers said the Lion Air plane that crashed
last month, killing 189 people, was
A preliminary report revealed that technical problems had
been reported in previous flights.
The 737 Max is a new version of the original Boeing 737 and
has become the best-selling aircraft.
The preliminary report details what the authorities know
about the short time the plane was in the air, but the investigators said it
did not give a definitive cause to the accident.
What does the report contain?
The findings of the National Transportation Safety Committee
(KNKT) suggest that Lion Air put the aircraft back into service when it had had
problems with previous flights.
The pilots appeared to have problems with an automated
system designed to prevent the aircraft from being stuck, a new feature of the
737 Max family.
Anti-lock systems prevent an aircraft from heading too far,
where it could lose lift.
However, during the October 29th flight, the aircraft's
automatic antilock system had forced the aircraft to sting, even when the
aircraft was not stopping, likely due to a defective sensor, according to the
report.
The pilots tried to correct this by pointing the nose up,
until the system repelled it again. It happened more than 20 times.
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The reason why pilots did not use procedures to disable the
automated system is unclear.
Nurcahyo Utomo, head of the National Transportation Safety
Committee, said it was "too early to conclude" whether the disaster
recovery system contributed to the accident.
He added that the plane had encountered similar problems
during his previous flight between Denpasar in Bali and Jakarta.
"In our opinion, the aircraft was no longer airworthy
and should not have continued," he said. However, the report of the
committee itself does not explain this conclusion.
The report states that Lion Air's safety culture should be
improved and that the airline should ensure that the operations manual is
followed "to improve the safety culture".
It also states that the carrier must ensure that "all
transaction documents are duly completed and documented".
What does Boeing say?
In a statement, aircraft manufacturer Boeing said he was
"deeply saddened" by the loss of the Lion Air flight.
"As our customers and their passengers continue to
transport the 737 Max to hundreds of destinations around the world every day,
they believe the 737 Max is as safe as any plane flying through the air."
Boeing stated that "the appropriate procedure for
dealing with the movement of the unintentional horizontal stabilizer" was
included in the corresponding flight manuals.
He added that the preliminary report showed that the correct
procedures for neutralizing the nose of the aircraft that had been pushed to
the ground had been carried out during the Denpasar flight, the day before the
accident.
However, it was unclear whether the procedures had been
followed during the flight that crashed on October 29, Boeing added.
In an interview with the BBC, Nurcahyo Utomo, KNKT's chief
of aviation, appeared to challenge Boeing's story about flight manuals.
"We did not find any information in the manual corresponding
to the new function of the 737-MAX, related to the function of the blocking
prevention system," he said.
Some pilots also complained that they did not receive all
the relevant information about the differences between the latest anti-lock
system and older models, according to US media.
How did the accident of October 29th develop?
The aircraft was on a one-hour trip to the western city of
Pangkal Pinang when it fell.
The plane crashed after a request from the pilot for
permission to return to the airport a few minutes after taking off from
Jakarta.
Researchers had previously revealed that the aircraft,
during previous flights, had encountered technical problems related to speed
and altitude readings.
Therefore, the "angle of attack" sensor, which
contributes to these readings, had been modified the day before the shock.
The aircraft's flight data recorder has been found, but the
authorities have still not located the flight recorder.