Indonesian investigators are expected Wednesday to release a preliminary report into the Lion Air plane crash last month that saw all 189 on board killed when the nearly new jet slammed into the sea.
The Boeing 737 MAX vanished from radar about 13 minutes after taking off from Jakarta on October 29, crashing into waters off Indonesia's northern coast moments after it had asked to return to the capital.
The findings are not expected to pinpoint a definitive cause of the accident, but may shed more light on why one of the world's newest and most advanced commercial passenger planes fell from the sky.
So far, investigators have said the doomed aircraft had problems with its airspeed indicator and angle of attack (AOA) sensors, prompting Boeing to issue a special bulletin telling operators what to do when they face the same situation.
An AOA sensor provides data about the angle at which air is passing over the wings and tells pilots how much lift a plane is getting. The information can be critical in preventing an aircraft from stalling.
The APA, a US airline pilots union, said that carriers and pilots had not been informed by Boeing of certain changes in the aircraft control system installed on the new MAX variants of the 737.
The Indonesian National Transportation Safety Committee has retrieved one of the plane's black boxes -- the flight data recorder -- but is yet to locate the cockpit voice recorder.
Black box data showed the plane had an airspeed indicator issue on multiple earlier flights, investigators said.
Concerns have been raised by news that Lion Air kept putting the plane back into service despite repeatedly failing to fix the problem in the days leading up to the fatal flight.
While Boeing has come under fire for possible glitches on the 737 MAX -- which entered service just last year -- the accident has also resurrected concerns about Indonesia's poor air safety record, which until recently saw its carriers facing years-long bans from European Union and US airspace.
Lion Air Flight JT610 plunged into the Java Sea less than half an hour after taking off on a routine flight to Pangkal Pinang city.
Authorities have called off the grim task of identifying victims of the crash, with 125 people officially recognised after testing on human remains that filled some 200 body bags.