There are also procedures for pilots to follow in the event of missing data from damaged sensors on the fuselage, but it remained unclear how much time the crew of flight JT610 had to respond at the relatively low altitude of around 5,000ft.
"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", the Chicago-based planemaker said in a statement.
JAKARTA, Indonesia-A crucial sensor was replaced on a Lion Air jet the day before it plunged into the Java Sea, and that sensor replacement may have exacerbated other problems with the plane, Indonesian investigators said November 7. The FAA said it was mandating that airlines follow the Boeing bulletin.
The FAA said erroneous data from the "angle of attack" sensor, which helps prevent the plane from stalling and diving, could cause flight crew to have difficulty controlling the airplane and lead to "excessive nose-down attitude, significant altitude loss, and possible impact with the terrain".
"The point is that after the AOA [sensor] is replaced the problem is not solved, but the problem might even increase".
The plane maker said local aviation officials believed pilots might have been given wrong information by the plane's automated systems before the fatal crash.
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.
"They should have been completely engaged in what was going on inside that cockpit, and any kind of warning that came up, they would have been wise to pay attention to it", Curtis said. Pilots flying with an AOA sensor generating erroneous inputs to the system can experience the inability to engage the aircraft's autopilot system, among other problems.
Investigators are expected to focus on how a single sensor's failure resulted in a faulty command that didn't take into account information from a second sensor, said John Cox, CEO of Safety Operating Systems.
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.
"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.
"A "ping" has been detected from the second black box but the signal was very weak, possibly because it was encased in mud", said Nurcahyo Utomo, an air accident official at the transportation safety committee (KNKT).
The DGCA had reviewed the performance of Boeing 737 MAX 8 planes operated by Jet Airways and SpiceJet.
Indonesian officials said on Wednesday they would extend the search by three days. Everyone on board was killed when it plunged into the sea moments after takeoff.