Thursday, November 29, 2018

'Lion Air jet that crashed killing 189 was not airworthy’

Jakarta: A Lion Air jet that crashed into the sea off Indonesia last month was not in an airworthy condition on its second-to-last flight, when pilots experienced similar problems to those on its doomed last journey, investigators said on Wednesday. Contact with the Boeing 737 MAX jet was lost 13 minutes after it took off on October 29 from Jakarta heading north to the tin-mining town of Pangkal Pinang. Indian carriers Jet Airways and SpiceJet too use Boeing 737 MAX.

In a preliminary report, Indonesia’s transport safety committee (KNKT) focused on the airline’s maintenance practices and pilot training and a Boeing anti-stall system but did not give a cause for the crash that killed all 189 people on board.

The report unveiled fresh details of efforts by pilots to steady the jet as they reported a “flight control problem”, including the captain’s last words to air traffic control asking to be cleared to “five thou” or 5,000 feet.

Information retrieved from the flight data recorder showed the “stick shaker” was vibrating the captain’s controls, warning of a stall throughout most of the flight. The captain was using his controls to bring the plane’s nose up, but an automated anti-stall system was pushing it down.

Pilots flying the same plane a day earlier had experienced a similar problem, en route from Bali to Jakarta, until they used switches to shut off the system and used manual controls to fly and stabilise the plane, KNKT said. “The flight from Denpasar to Jakarta experienced stick shaker activation during the takeoff rotation and remained active throughout the flight,” the committee said. “This condition is considered as un-airworthy condition and the flight should have been discontinued.”
Pilots of that flight reported problems to Lion Air’s maintenance team, which checked the jet and cleared it for takeoff the next morning. Former Boeing flight control engineer Peter Lemme said stick shaker activation was “very distracting and unnerving”. KNKT investigator Nurcahyo Utomo said the agency had not determined if the anti-stall system, which was not explained to pilots in manuals, was a contributing factor. In a statement, Boeing, which has said procedures for preventing an antistall system activating by accident were already in place, said pilots of the penultimate flight had used that drill but noted the report did not say if pilots of the doomed flight did so.
29/11/18 Reuters/Times of India

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