Crashed Sriwijaya Air jet had engine thrust imbalance - preliminary
report
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[February 10, 2021]
By Fransiska Nangoy and Bernadette Christina Munthe
JAKARTA (Reuters) - The Sriwijaya Air plane
that crashed last month killing 62 people had an imbalance in engine
thrust that eventually led the plane into a sharp roll and then a final
dive into the sea, a preliminary report by investigators said on
Wednesday.
When the 26-year-old Boeing Co 737-500 plane reached 8,150 feet (2,484
m) after take-off, the left engine throttle lever moved back while the
right lever stayed in its original position, Indonesia's National
Transportation Safety Committee (KNKT) said in its report.
"We don't know if it's broken or not, but it's an anomaly because the
left moved far back, the right did not as though it was stuck," KNKT
investigator Nurcayho Utomo told reporters of the levers.
At about 10,900 feet, the autopilot disengaged and the plane rolled to
the left more than 45 degrees and started its dive, according to the
report.
The Sriwijaya accident is Indonesia's third major airline crash in just
over six years and has shone a spotlight on the country's poor air
safety record.
Starting with just one plane in 2003, Sriwijaya has become the country's
No.3 airline group, aided by its strategy of acquiring old planes at
cheap prices and serving routes neglected by competitors.
There had been two prior problems reported with the autothrottle system
that automatically controls engine power based on maintenance logs, but
the issue was rectified on Jan. 5, four days before the crash, KNKT
said.
A working autothrottle is not required for a plane to be dispatched as
pilots can control the thrust levers manually with their hands.
Divers are still searching for the plane's cockpit voice recorder which
could help investigators understand the actions taken by the pilots,
both of whom were experienced with 17,900 hours for the captain and
5,100 hours for the first officer.
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Family members of the passengers of Sriwijaya Air flight SJ 182,
which crashed into the sea, react while throwing flowers and petals
from the deck of Indonesia's Naval ship KRI Semarang as they visit
the site of the crash to pay their tribute, at the sea off the
Jakarta coast, Indonesia, January 22, 2021. REUTERS/Ajeng Dinar
Ulfiana
The report highlighted the importance of upset recovery training for
pilots and the recognition of repetitive plane defects, just over
six years after an AirAsia Indonesia crash where those were among
the issues raised.
KNKT said that following the crash Sriwijaya had taken safety
actions including adding upset recovery training in its next pilot
proficiency check and reminding engineers that repetitive defects
must be handled in accordance with safety manuals.
The airline sent a memo to pilots reminding them to write detailed
reports to help engineers troubleshoot problems.
The Directorate General of Civil Aviation also discussed the
handling of repetitive problems and upset prevention and recovery
training with other Indonesian operators after the crash, KNKT said.
Boeing said it would continue to support the investigation.
The preliminary report, as is standard, laid out factual information
obtained to date but did not list the contributing factors to the
crash. That will require further investigation.
Safety experts say most air accidents are caused by a combination of
factors that can take months to establish. Under international
standards, the final report is due within a year of the crash.
(Reporting by Fransiska Nangoy and Bernadette Christina Munthe;
additional reporting by Agustinus Beo Da Costa and Gayatri Suroyo;
writing by Jamie Freed; Editing by Gerry Doyle and Kim Coghill)
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