Boeing issues operational manual to airlines following Lion Air crash

An Indonesian rescue team lift a pair tires from the ill-fated Lion Air flight JT 610 off Karawang in the Java Se

An Indonesian rescue team lift a pair tires from the ill-fated Lion Air flight JT 610 off Karawang in the Java Se

The jet's airspeed indicator malfunctioned on its last four flights, and that problem was related to the sensor issue, said Soerjanto Tjahjono, chairman of Indonesia's National Transportation Safety Committee, on Wednesday.

Experts say the notice could be about the "angle of attack", which is the angle of the wing relative to oncoming air stream, a measure that indicates if a plane is likely to stall.

The Chicago-based manufacturer said investigators probing the crash of Flight JT610, in which all 189 on board were killed, had found that one of the "angle of attack" sensors on the brand new plane had provided incorrect readings.

Soerjanto Tjahjono, chairman of Indonesia's National Transportation Safety Committee, said the problem was similar on each of the four flights, including the doomed one on October 29.

Airspeed indicators have been around for decades to tell pilots how fast they are flying.

Boeing declined to comment when contacted by Reuters. Erroneous readings from the AOA sensor could push the plane into an aggressive, unwarranted dive.

The Lion Air investigation comes after Indonesia's government ordered an inspection of all Boeing 737 Max 8 planes in the country.

Lion Air reportedly knew that the plane - a brand-new Boeing 737 MAX 8, which the low-priced carrier had been using for only a few months - had malfunctioned on its second-to-last flight.

The focus has been on the Lion Air 737's speed and altitude sensors made up of the Pitot Tube and Static Port which compare air pressure to give flight data such as airspeed, altitude, and altitude trend and is connected to the pilot's instruments and the plane's computers the autopilot. That last step appears to be what the Lion Air pilots didn't do, perhaps because they couldn't recall the procedure or they weren't fully aware of what precisely was happening.

"Any action the FAA would take regarding that incident would have to wait until we have findings, until we have information", Elwell said in Washington.

The Boeing 737 MAX is a more fuel-efficient version of the manufacturer's best-selling single-aisle 737 series.

After an engine on a Southwest Airlines plane fractured earlier this year over Pennsylvania, killing a passenger, CFM International issued multiple bulletins to operators of its CFM56-7B power plants.

The U.S. Federal Aviation Administration said it would issue an airworthiness directive to make Boeing's advice mandatory. In the early days of the jet age, the elevator trim system was linked to several accidents. They are paired with separate indicators measuring the degree to which the nose is pointed up, down or level.

The FAA, which regulates the USA aviation industry, has not received any reports of airspeed issues with the model in the United States, said a person familiar with its reviews, who asked not to be named as he was not authorised to speak. That case didn't involve the angle-of-attack system.

Alan Diehl, a pilot and safety consultant, said the report that the same problem happened four times and was never fixed suggests that the problem may have been intermittent, making it harder to pin down.

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