Boe­ing crash clues raise new ques­tions

Weekend Herald - - World - An­gus Whit­ley and Julie Johns­son

In­ves­ti­ga­tors are slowly piec­ing to­gether clues of how In­done­sia’s worst air dis­as­ter in two decades tran­spired, rais­ing ques­tions over how a near brand-new Boe­ing jet that had re­cur­ring in­stru­ment fail­ures was cleared for its ill-fated flight.

The Lion Air Max 8 plane’s an­gle-of-at­tack sen­sor, which helps air­craft main­tain the cor­rect pitch to stay air­borne, was re­placed the day be­fore the Oc­to­ber 29 crash af­ter er­ro­neous read­ings on a pre­vi­ous trip, the In­done­sia Na­tional Trans­porta­tion Safety Com­mit­tee said this week. Faulty air­speed read­ings plagued the jet on its last four flights be­fore it plunged into the Java Sea with 189 peo­ple aboard.

The rev­e­la­tions spurred Boe­ing to alert op­er­a­tors of the 737 Max air­craft world­wide that the air­flow sen­sor can pro­vide false read­ings in cer­tain cir­cum­stances. Mis­lead­ing data from that de­vice could trick the plane into point­ing its nose down.

That warn­ing and the in­ves­ti­ga­tion team’s state­ment sug­gest the pi­lots on JT610 may have been bat­tling with the air­craft as its com­put­ers com­manded a dive. In ad­di­tion, the faulty cock­pit data over mul­ti­ple flights lead­ing up to the ac­ci­dent and the re­place­ment of a wildly mis­lead­ing sen­sor have raised ques­tions about main­te­nance, over­sight and the plane’s suit­abil­ity for ser­vice.

“The air­craft, with that re­cur­ring prob­lem, should not have been re­leased to fly,” Neil Hans­ford, chair­man of Aus­tralian con­sul­tancy firm Strate­gic Avi­a­tion So­lu­tions who has worked with air­lines world­wide for more than 30 years, said. “It should have been grounded.”

The al­most brand-new plane, with just 800 hours of flight time, was cleared for the Oc­to­ber 29 flight af­ter main­te­nance overnight, Lion Air has said.

On a pre­vi­ous flight from Bali to Jakarta, the same jet’s an­gle-of-at­tack sen­sor feed­ing the cap­tain’s dis­plays reg­is­tered a 20-de­gree dif­fer­ence from the de­vice on the copi­lot’s side of the cock­pit, the com­mit­tee said. The mal­func­tion can cause the com­put­ers to er­ro­neously de­tect a mid­flight stall in air­flow, trig­ger­ing a dive to re­gain speed to keep fly­ing.

Mo­ments into the air­craft’s fi­nal flight, the pi­lots asked to re­turn to Jakarta but never turned back, ac­cord­ing to In­done­sia’s safety com­mis­sion and flight-track­ing data. Shortly af­ter­ward, JT610 plunged into the wa­ter, nos­ing down­ward so sud­denly that it may have hit speeds of 1000km/h.

In­ves­ti­ga­tors will want to ex­am­ine the pi­lots’ ac­tions, how flight crews were trained and whether main­te­nance that was per­formed was ad­e­quate, said Roger Cox, a for­mer US Na­tional Trans­porta­tion Safety Board in­ves­ti­ga­tor.

“I would def­i­nitely be look­ing at the man-ma­chine in­ter­face and how pi­lots re­spond,” said Cox, a for­mer air­line pilot who flew ear­lier ver­sions of the 737.

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