Lion Air: Sensor was replaced day before crash but problems persisted

Friday, 09 Nov, 2018

Boeing issues an operational update for 737.

On Tuesday, Indonesian investigators found that the Lion Air flight had a malfunctioning air speed indicator for its last four flights and crucially, at the time of the crash.

Both Boeing and the FAA are continuing to assist Indonesian officials in investigating the accident. The FAA also notified other regulatory agencies around the world, which typically follow the USA agency's lead on safety matters.

"Angle of attack" refers to the angle between relative wind and a reference line on the plane - the sensors' objective is to ensure that air flows over an aircraft's wings, Bloomberg reported.

Preliminary investigations into the Indonesia Lion Air flight 610 Boeing 737 MAX crash have indicated a problem with a sensor that alerts pilots about the possibility of aircraft stalling, especially when the nose is up post lift-off.

But what is disturbing is why Lion Air didn't pull this plane from service after repeated problems.

In the United States, Southwest Airlines now has 26 737 MAX planes in operation; American Airlines has 16.

The problem with the planes is in the "angle of attack" sensor which calculates the position of the plane relative to the air current.

Boeing shares rose less than one per cent to US$368.11 in premarket trading Wednesday in NY.

Essentially the Boeing bulletin tells the pilots to follow the manual's instructions. The committee said the pilots were dealing with an erroneous airspeed indication.

Just a week after a Lion Air passenger plane crashed into the Java Sea killing all the 189 people on board, another jet of the budget carrier has been involved in an accident.

On that October 28 flight, the pilot's and co-pilot's sensors disagreed by about 20 degrees. "Is this fatal? NTSC (National Transportation Safety Committee) wants to explore this", he said.

The plane is the latest generation of Boeing's workhorse narrowbody aircraft, with more than 200 delivered since it entered service a year ago and a total of 4,700 orders placed by airlines around the world.

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

It seems patently obvious to say that such situations shouldn't happen in this day and age-and clearly the investigation is still in its earliest stage-but it is troubling to see something so deadly transpire in the most modern aircraft in the Boeing fleet. The data are fed into computers made by Honeywell International Inc. for the plane.

The Federal Aviation Administration also plans to issue an airworthiness directive for the plane in question.

The angle of attack is incredibly important. If pilots aren't careful, they can cause severe nose-down trim settings that make it impossible to level a plane.