Failure to adjust the instructor led to the crash of the Indonesian airliner

Failure to adjust the instructor led to the crash of the Indonesian airliner

JAKARTA, Indonesia (AP) — Indonesian aviation investigators concluded Thursday that a nearly decade-long failure to properly repair a faulty autothrottle, pilots’ over-reliance on the plane’s automation system and inadequate training contributed to the latest crash of a Boeing 737-500. year, which killed 62 people.

Investigators from the National Transportation Safety Board said in their final report that the Sriwijaya Air plane’s maintenance records show that the auto-throttle problem had been reported by pilots 65 times since 2013 and was still unresolved when the 26-year-old plane crashed into the Java Sea. : After the flight from Jakarta on January 9, 2021.

Lead investigator Nurcahyo Utomo told a news conference that the pilots’ last conversation with air traffic control was about 4 minutes after takeoff, when they responded to an instruction to climb to 13,000 feet. The plane’s flight data recorder showed it reached an altitude of 10,900 feet and then began to descend, Utomo said.

He said the plane required less engine thrust as it approached its target altitude, but the autothrottle was unable to reduce power from the right engine due to friction in the mechanical system.

The autothrottle attempted to compensate by further reducing power to the left engine, reducing its output to 34%. The right engine’s power remained at its boost position, or about 92%, resulting in dramatically uneven thrust, the report said.

The pilot fought to lift the plane but “was unable to recover” and the plane rolled to the left, the report said.

A minute later, the flight data recorder indicated that the autothrottle had disengaged as the aircraft landed. The recorder stopped recording after a few seconds.

Autothrottle can be used by pilots to set speed automatically, thereby reducing their workload and wear and tear on their engines. The movements of the automatic throttle are linked to 13 other components of the plane, the report said.

Many of the causes of the plane crash were revealed in a preliminary report released by Indonesian authorities last year. A final report released Thursday provided new details about the pilots’ responses.

Utomo said inadequate training “contributed to the pilot’s inability to prevent and recover from the condition.”

The pilots’ over-reliance on the plane’s automation system may have led to insufficient cockpit monitoring so that the flight deviation was not immediately noticed, the report said.

Utomo said the voice data recorder was working on only one audio channel, and another channel that was supposed to record all the voices in the cockpit was filled with an unknown hum that prevented investigators from fully analyzing the coordination of the two pilots.

The report concluded that multiple attempts to repair the automatic throttle over the years failed because they did not adequately correct the mechanical problem.

Investigators worked with Boeing and engine maker General Electric to examine information from the flight data recorder. A team from the US National Transportation Safety Board and the Federal Aviation Administration have also joined the investigation.

The plane was out of service for almost nine months due to the reduction of flights due to the coronavirus epidemic. Regulators and the airline said they had passed inspections before resuming commercial flights in December 2020.

The disaster renewed concern about the safety of Indonesia’s aviation industry, which has expanded rapidly since the country’s economy opened up after the ouster of dictator Suharto in the late 1990s. The United States banned Indonesian airlines from operating there in 2007, but lifted the measure in 2016, citing improvements to meet international aviation standards. The European Union lifted the similar ban in 2018.

Sriwijaya Air, Indonesia’s domestic airline founded in 2003, has had only minor safety incidents in the past, although a farmer was killed in 2008 when a plane skidded off the runway on landing due to a hydraulic failure.

In 2018, a Boeing 737 MAX 8 operated by the Indonesian airline Lion Air crashed, killing 189 people. The automated flight control system played a role in the crash, but the Sriwijaya Air plane did not have such a system.



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