Readings show Lion Air pilots struggled with Boeing 737 system before crash

Minnie Murray
November 29, 2018

The new 737 MAX 8 plunged into the Java Sea on October 29, killing all 189 people on board.

As soon as the pilots used manual controls to push up the jet's nose, the automatic system sent commands to push it back down, according to reports about the Indonesian findings.

Nurcahyo Utomo, an investigator for Indonesia's National Transportation Safety Committee, at a news conference announcing preliminary findings on their investigation on the crash of Lion Air flight 610, in Jakarta, Indonesia on Wednesday. It is activated when angle of attack (AOA) sensors indicate that the airframe is in a dangerously high angle and attempts to correct it by pushing the plane nose down.

An "angle of attack" sensor gave faulty readings throughout the short flight, triggering a system that automatically pointed the plane's nose down more than two dozen times, with pilots responding by manually fighting to correct the pitch.

Once the jet was airborne, the pilots appeared to have been overwhelmed, said another of the crash investigators, Ony Suryo Wibowo.

The Lion Air jet that crashed on October 29 received a "stick shaker" warning of an impending stall as it took off, but the crew reacted differently to pilots who had experienced a similar problem the night before.

"The problem is if multiple malfunctions occur all at once, which one should be prioritized?"

The Indonesian investigation is continuing with help from USA regulators and Boeing. The manufacturer played up the possibility of pilot error. They also ran safety checklists.

The pilot should have discontinued the flight, the National Transport Safety Committee found. The computer system that failed, called the Maneuvering Characteristics Augmentation System, or MCAS, sought to make the 737 MAX operate as similarly as possible to the older 737s, despite having larger engines placed farther forward on the wings.

The MCAS is Boeing's new anti-stall system, installed on MAX planes.

They repeatedly told air traffic control they had a flight control problem.

Information from the Lion Air jet's flight data recorder was included in a briefing for the Indonesian Parliament. The government report suggests the airplane should have been removed from service because of earlier reports about problems.

Concerns have been raised by news that Lion Air kept putting the plane back into service despite repeatedly failing to fix the problem in the days leading up to the fatal flight.

They recommended that Lion Air, a fast-growing low-priced airline based in Jakarta, ensures that pilots follow proper procedures "to improve the safety culture".

Lion Air chief executive Edward Sirait said he had not yet read the KNKT report but would comply with all the investigators' recommendations.

"They will be looking for more precise reporting of problems (by pilots), and certainly a better maintenance response", she said.

The report is the most detailed look yet from authorities at the 11 minutes the plane was in the air.

"Had they fixed the airplane, we would not have had the accident", he said.

The report discussed Lion Air's maintenance practices and an anti-stall system in the aircraft; investigators said it was "too early" to identify a firm cause for the crash.

Boeing has a great deal at stake in defending its plane.

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.

U.S. aviation groups, including the Federal Aviation Authority, say Boeing didn't tell them about new sensors in the automated anti-stall system that were added to their 737 MAX aircraft.

Investigators are exploring whether faulty sensor data might have caused the automatic system to kick in and force the plane's nose down.

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