American regulators have issued an emergency warning to operators of Boeing's newest jet airliner after evidence that a deadly crash in Indonesia last week was caused by the failure of a crucial instrument.
The US aerospace giant has issued an "operations manual bulletin" to airlines using the aircraft, telling them how to deal with "erroneous input" from sensors.
The new information about Lion Air Flight 610 raises multiple questions investigators will want to examine on the pilots' actions, how flight crews were trained and whether the maintenance performed on the system was adequate, said Roger Cox, a former NTSB investigator.
The Boeing 737 MAX is the fastest-selling plane in company history.
Boeing issues an operational update for 737.
To avoid having the problem repeat, pilots may deactivate the stabilizer trim system, according to The Air Current's explanation.
The directive gives regulatory weight to Boeing's safety bulletin that it sent to operators of Boeing 737 MAX 8 and MAX 9 planes based on findings from the ongoing Indonesian investigation into the October 29 crash of a Lion Air jet.
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 1,500 metres.
Aircraft and engine manufacturers routinely send bulletins to air carriers noting safety measures and maintenance actions they should take.
"The draft of what will be conveyed by Boeing this morning has been presented to us", said air accident investigator Nurcahyo Utomo.
Boeing, which manufactured the Lion Air plane, issues safety-related bulletins, and had previously circulated instructions about what flight crews should do if sensors fail.
"This is a tragedy, but (the safety bulletin) says absolutely nothing about the design of the plane and its major subsystems", TEAL Group aviation analyst Richard Aboulafia told Business Insider.
He said the pilot had landed the plane safely on that occasion.
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.
"Over the last 40 years, Boeing and Chinese partners have built deep relations in all industrial chains, including the research of new technologies, parts manufacturing as well as flight maintenance and modification", the statement said.
The warning is based on based on preliminary findings from last week's crash of one of the planes off the coast of Indonesia, said the person, who asked not to be named discussing details that are still confidential.