"This AD requires revising certificate limitations and operating procedures of the airplane flight manual (AFM) to provide the flightcrew with runaway horizontal stabiliser trim procedures to follow under certain conditions".
"The Indonesian National Transportation Safety Committee has indicated that Lion Air flight 610 experienced erroneous input from one of its AOA (angle of attack) sensors", Boeing said in a statement on its website on Wednesday. 737 MAX passenger plane slammed into the sea on October 29, only minutes after takeoff from Jakarta en route to Bangka island near Sumatra.
If something goes wrong in the sensor and it registers a false positive, it's possible for a plane to enter into a nosedive, similar to what happened on the Lion Air flight.
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. That sensor is meant to maintain air flow over a plane's wings but if it malfunctions can lead to an aerodynamic stall - which can cause aircraft to abruptly dive.
"The point is that after the AOA [sensor] is replaced the problem is not solved, but the problem might even increase".
Experts have said the angle of attack is a crucial parameter that helps the aircraft's computers understand whether its nose is too high relative to the current of air - a phenomenon that can throw the plane into an aerodynamic stall and make it fall.
There are audio signals and physical warnings that can alert the pilot to malfunctioning equipment or other dangers, said Todd Curtis, director of the Airsafe.com Foundation.
Chairman Soerjanto Tjahjono said the airspeed indicator and sensor problems were related.
"We don't know yet where the problem lies, what fix has been done, what their reference books are, what components have been removed", said Nurcahyo Utomo, the KNKT sub-committee head for air accidents.
The operations-manual bulletin was issued Tuesday, Boeing said in a statement posted to Twitter, and tells crew to use existing guidelines when dealing with erroneous inputs from the so-called angle of attack sensor.
"The draft of what will be conveyed by Boeing this morning has been presented to us", said air accident investigator Nurcahyo Utomo.
In the United States, Southwest Airlines now has 26 737 MAX planes in operation; American Airlines has 16.
Divers have recovered one of the two "black boxes" - the flight data recorder - but are still searching for the cockpit voice recorder, in the hope it will shed more light on the cause of the disaster.
Indonesia's search and rescue agency on November 7 extended the search effort for a second time, saying it will continue until Sunday.
captionItems recovered from the crash of Lion Air Flight 610.sourceEddy Purwanto/NurPhoto via Getty ImagesIn addition, the analyst explained that such bulletins were quite common, though they seldom follow such a tragedy.
Lion Air is one of Indonesia's youngest and largest airlines, flying to dozens of destinations at home and internationally.