Published: Thu, November 29, 2018
Global | By Craig Ferguson

Lion Air jet should have been grounded before fatal flight, Indonesia says

Lion Air jet should have been grounded before fatal flight, Indonesia says

Indonesia's National Transportation Safety Committee (KNKT) sub-committee head for air accidents, Nurcahyo Utomo, speaks next to deputy chief of KNKT Haryo Satmiko and KNKT air crash investigator Ony Suryo Wibowo during a news conference on its investigation into a Lion Air plane crash last month, in Jakarta, Indonesia November 28, 2018.

Pilots experienced several problems with the aircraft in the days leading up to the October 29 crash, investigators said - including a faulty airspeed sensor, altitude indicators and angle-of-attack sensors that should have grounded the plane.

Briefing reporters on the aircraft's black box data, the investigators said they were still struggling to understand why the plane crashed but they cited multiple factors centered on faulty sensors and an automatic safety system that repeatedly forced the plane's nose down despite the pilots' efforts to correct the problem.

However, Nurcahyo Utomo told the BBC: "We haven't found the information in the manual relevant to the new feature to the 737- MAX, related to the feature for the stall prevention system".

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. Earlier this month, pilots at American Airlines and Southwest Airlines complained that they had not been given all information about the new automated anti-stall safety system on the MAX.

The model of plane involved in the crash, a Boeing Max 8 jet, was only rolled out globally past year.

They reported the issue to Lion Air, which checked the 737 and approved it for its final takeoff the next day.

After landing, the pilot reported the malfunction to the engineers, who performed a number of maintenance checks on the aircraft before it was used for the Pangkalpinang flight.

Investigators had previously revealed that the plane, on previous flights, had experienced technical problems related to airspeed and altitude readings. The information can be critical in preventing an aircraft from stalling.

The KNKT said MCAS was not described in the Lion Air flight manual before the crash, nor in those used by American airlines according to United States pilot unions.

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

The aircraft's pilots asked to return to Jakarta just two minutes after takeoff, reporting a "flight-control problem" but didn't specify what it was.

The plane's cockpit voice recorder, which would provide more information about what happened in the cockpit, has yet to be found.

The wreckage was identified 370m (1,200ft) from the last recorded aircraft position, and the damage to the aircraft suggested a high energy impact, the report said. The captain's stick shaker activated shortly after takeoff and remained nearly continuously active. "Therefore, he is responsible for ensuring the aircraft is in condition for safe flight and must discontinue the flight when un-airworthy mechanical, electrical, or structural conditions occur".

The investigation team is also planning to conduct aircraft simulator exercises in the Boeing engineering simulator configured for 737 MAX 8. It is flown or is on order by close to 40 airlines, with Lion Air in the process of receiving more than 200 of jets.

The Indonesian investigation is continuing with help from USA regulators and Boeing.

Members of the National Transportation Safety Committee lift a box containing the flight data recorder from a crashed Lion Air jet.

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