Boeing and the Federal Aviation Administration has issued a safety alert to flight crews about potential erroneous readings from a sensor in its latest 737 Max 8 aircraft, following last month's Lion Air crash in Indonesia.
On November 6, Boeing said it had issued an Operations Manual Bulletin (OMB) directing operators to existing flight crew procedures to address circumstances where there is erroneous input from an AOA sensor.
Indonesia authorities extended on Wednesday a search for victims of a plane crash last week, when all 189 on board a Lion Air flight were killed, and for the aircraft's second black box, the cockpit voice recorder.
Indonesian investigators said this week the plane had an air-speed indicator problem on the doomed flight and on three previous journeys.
The newspaper said the findings suggest investigators could be looking at a software problem or a mistaken interpretation by flight crew as having played key roles in the Lion Air crash.
It was found that on the flight that crashed in Asia this sensor was giving off incorrect data, meaning the pilots weren't flying in the right position. Chairman Soerjanto Tjahjono said the airspeed indicator and sensor problems are related.
The FAA said the "erroneous inputs can potentially make the horizontal stabilisers repeatedly pitch the nose of the airplane downward, making the aircraft hard to control".
This comes in the wake of a new Lion Air Boeing 737 MAX crashing into the sea not long after leaving Jakarta, Indonesia, and killing all 189 passengers on board. It is believed the plane plunged at over 600mph, but the cause of the accident is still under investigation.
He said the pilot had landed the plane safely on that occasion.
The Indonesian Ministry of Transportation has begun an audit of Lion Air (JT, Jakarta Soekarno-Hatta) and has also started impromptu checks of various other Indonesian carriers following the crash of one of the low-priced carrier's B737-8s on October 29. But the urgency of a fatal accident can trigger a flurry of such notices. In addition, a system known as pitch trim can be changed to prompt nose-up or nose-down movement. Erroneous readings from the AOA sensor could push the plane into an aggressive, unwarranted dive. That is enough to send the plane out of control and cause it to fall to the ground.
The new details - gleaned from a recovered flight data recorder - come after the government said it was launching a "special audit" of the budget carrier's operations. One of the pilots had trimmed the plane to push the nose down while trying to climb after aborting a landing, the report said.