Pilots struggled to control Lion Air jet before it crashed into sea

Posted December 01, 2018

Data from the jetliner that crashed into the Java Sea last month shows the pilots fought to save the plane nearly from the moment it took off, as the Boeing 737's nose was repeatedly forced down, apparently by an automatic system receiving incorrect sensor readings.

Sensors were misfiring on the almost new Boeing Co.

The Lion Air crash is the world's first involving the 737 MAX jet, a fuel-efficient version of Boeing's workhorse narrow-body introduced into service globally a year ago.

The state-of-the-art 737 MAX 8 airplanes do not have this feature, yet the company failed to prominently warn pilots of the change even as airlines worldwide began taking delivery of the new jets previous year, pilots say. And, after that flight, pilots failed to cite all the breakdowns when they requested maintenance.

Furthermore, the KNKT will conduct further analysis based on the Lion Air jet's quick access recorder (QAR) they obtained, which has recorded 385 flights that will be further evaluated to see if similar problems were experienced by previous flights.

Several Lion Air aircraft have been damaged beyond fix.

Accident investigators often speak of the "Swiss cheese" theory of airline accidents.

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"What they were focused on was keeping the airplane in the air", said Clint R. Balog, a pilot and aeronautics expert at Embry-Riddle Aeronautical University. All it takes to prevent a crash is to block the hole at any point.

That's one of the findings in a preliminary report released today by Indonesia's National Transportation Safety Committee. Dennis Tajer, a spokesperson for the Allied Pilots Association at American Airlines Group Inc., also expressed that his union's members were troubled by Boeing's directive.

"The crew wasn't handling the aircraft correctly", Haueter told ABC News, adding that the pilots should have returned to the airport upon the first sign of trouble.

And the problem appeared to get worse in spite of attempts at fix.

It said that the preliminary report showed that the correct procedures to counter the plane's nose being pushed down were carried out during the Denpasar flight the day before the crash.

At the center of the ongoing investigation into the nation's worst air disaster in two decades is a sensor that measures how high or low the plane's nose is pointing relative to the oncoming air - its so-called angle of attack.

New details of Flight JT610's final moments were also included in the report.

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As soon as the October 28 flight from Bali to Jakarta lifted off, a device known as a "stick shaker" - which is created to alert pilots to an imminent aerodynamic stall - activated with its unmistakable vibrations on the control column and loud thumping noise.

He said the agency had not yet determined if the anti-stall system, which was not explained to pilots in manuals, was a contributing factor. Such an issue was significant enough that pilots should have landed under Indonesia regulations, even though the checklists never instructed the crew to do so, according to the NTSC.

"This is a report of facts", said Mr Nurcahyo. The NTSC issued a recommendation that the airline encourage pilots to divert flights in those conditions.

"I don't think the airplane was ready for passenger service because they had not validated that they had fixed the problem", he said.

SCHAPER: The preliminary report calls for improved maintenance procedures and more pilot training.

Even though the angle-of-attack sensor seems to be at the center of the confusing alarms and the final dive before the crash, the pilots on the October 28 flight showed that it could be overcome. The report repeats recommendations that pilots be better versed in emergency procedures aware of past aircraft problems.

On the plane's 11-minute final flight, the Boeing safety software attempted to push the nose down more than 30 times, but the pilots - a different crew than had flown the jet the day before - never used those switches. Sirait told reporters in Jakarta the airline has always upheld a safety culture.

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The search for the cockpit voice recorder is proving hard after investigators said last week its "ping" signal was no longer being detected. "Is this true? If it's like that, it seems that the report is finished". That will take time still - KNKT said it plans to finish a complete study within 12 months of the accident. That led an automated flight control system to take over and point the nose down, corrective action that wasn't needed.