Report by : Gan Yung Chyan
/ KUCINTA SETIA
Distributed to All Press & Travel Professionals
Image courtesy : Visual China
On 28 November 2018, Indonesia announced at the press conference a preliminary investigation report detailing the details of the Lion Air crash that killed 189 people on 29 October 2018. Nurcahyo Utomo, Head of the Aviation Department of the Indonesian National Transport Safety Committee, detailed the report.
The New York Times quoted the report as saying that in the 11-minute flight, the nose of the aircraft automatically sagged more than twenty times. The pilot had been fighting with time to pull the nose of the aircraft in question high, but this aircraft crashed in the sea.
According to the National Broadcasting Corporation (NBC), Indonesian investigators also said on the same day that the Boeing 737 MAX had encountered similar problems in a flight before the crash and did not reach airworthiness.
It is reported that the aircraft's penultimate flight from the Indonesian city of Denpasar to the capital Jakarta, encountered similar problems during the flight, until the pilot closed the abnormal system, using manual control to stabilize the aircraft, the crisis was resolved.
The pilot reported the problem to the Lion Air maintenance team after that flight, and the maintenance team also inspected the aircraft. The next morning, the plane took off for Pangkal Pinang and a tragedy followed.
Investigators said that the aircraft had this situation, indicating that it was not in an airworthy condition. However, the report did not give the exact cause of the crash.
Above : The height of the wrecked aircraft after the takeoff map. Source : The New York Times
On 12 November 2018, Reuters disclosed the preliminary investigation results of the Indonesian investigation team. It is reported that the 737 MAX model recently installed a tail-rotation protection system, which is considered to be related to the cause of the crash, but the relevant flight manual and training program do not mention this system.
In combination with the black box record, the investigation team believes that one of the reasons for the crash is the data anomaly on the "angle of attack sensor" on the aircraft. A new tail-rotation system installed on the machine has an automatic nose-down system. According to information released by Boeing afterwards, the system on the 737 MAX model has the ability to bypass the driver's control. Even if the hand is pulled up manually, the descent process will be repeated automatically after five seconds.
The investigation team pointed out that the operating manual and training program provided by Boeing did not mention this newly installed system.
After the accident, Boeing notified airlines, unions and training institutions that a new system installed on the 737 MAX model may cause the aircraft to lower the nose in some cases to avoid tail spin.
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