Crashed Lion Air Boeing Jet Previously Had Problems with Altitude, Speed Sensors

Erroneous sensors could be an explanation for the flight track data, said John Cox, president of Safety Operating Systems and a former airline pilot. But Cox and others cautioned that it’s too soon to say what happened on the Lion Air flight and some of the flight data — such as speeds that weren’t extreme and none of the highly abrupt maneuvers that preceded the Air France jet’s loss of control — may suggest some other cause

 

The Lion Air jet that crashed into the Java Sea off Indonesia earlier this week had experienced problems with the sensors used to calculate altitude and speed on its previous flight, an issue that could help explain why the plane dove into the water.

 

Pilots on the nearly new Boeing Co. 737 Max 8 reported the issue after flying from Denpasar to Jakarta the night before the accident, Lion Air spokesman Danang Mandala Prihantoro said Wednesday. The instruments were checked by maintenance workers overnight and the plane was cleared to fly, Prihantoro said.
 

While it will be days or weeks before definitive information emerges in the crash shortly after takeoff with 189 people aboard, discrepancies in speed and altitude readings can cause confusion on the cockpit and have led to accidents in the past, including the 2009 crash of an Air France plane in the Atlantic Ocean.

 

Flight-tracking data before the two-month old Lion Air jet crashed showed the plane was varying its altitude and speed, a possible indication that the pilots weren’t getting accurate information from the aircraft’s air-pressure sensors.

 

Erroneous sensors could be an explanation for the flight track data, said John Cox, president of Safety Operating Systems and a former airline pilot. But Cox and others cautioned that it’s too soon to say what happened on the Lion Air flight and some of the flight data — such as speeds that weren’t extreme and none of the highly abrupt maneuvers that preceded the Air France jet’s loss of control — may suggest some other cause.

 

Indonesian search teams retrieved the flight data recorder Thursday after more than three days of hunt for the wreckage. They have yet to locate the cockpit voice recorder.

 

Inspections of the 737 Max 8 aircraft operated by Lion Air and Garuda Indonesia since the accident found no technical issues, according to a statement by the country’s Transport Ministry. A review of maintenance documents found no additional issues were reported on the airspeed and altimeter system in the past 3 months.

 

However, in a crackdown Thursday, the ministry ordered Lion Air to suspend its director of maintenance and engineering, managers in charge of quality control and fleet maintenance and the engineer who signed off on the plane before take-off. The measures were taken to facilitate a smooth probe, it said.


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