Indonesian investigators have said the cockpit voice recorder from a crashed Lion Air Boeing Co 737 MAX 8 jet last October showed pilots were searching for the right checklist in their handbooks and were experiencing airspeed and altitude issues.
Investigators said they have 90% of the data needed for a final report on the October crash that killed 189 people.
The report is now expected to be released in August.
Nurcahyo Utomo, an investigator at Indonesia's national transportation committee (KNKT) said the recording showed there was "panic" in the cockpit in the last 20 seconds of the flight.
"At the end of the flight it seemed the pilot felt he could no longer recover the flight, then the panic emerged," he said while declining to say which of the two pilots panicked.
The investigation has taken on new urgency after a second 737 MAX 8 crash at Ethiopian Airlines last week killed 157 people and led to the global grounding of the model.
French air accident investigation agency BEA said on Tuesday that the flight data recorder in the Ethiopian crash showed "clear similarities" to the Lion Air disaster.
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Investigators are also considering how a computer ordered the plane to dive in response to data from a faulty sensor.
They are also examining whether the pilots had enough training to respond appropriately to the emergency, among other factors.
A different crew on the same plane the evening before encountered the same problem with the computer ordering the plane's nose down but solved it after running through three checklists, according to a preliminary report released by KNKT in November.
That crew did not pass on all of the information about the problems they encountered to the pilots of the doomed flight, the report said.
Investigators have confirmed there was a third, off-duty pilot in the cockpit that evening.
That was not mentioned in the preliminary report because they had not interviewed the pilot at that stage as they worked to get the report out fast, Mr Utomo said.
Reuters yesterday reported it was a captain at Lion Air's full-service sister carrier Batik Air who solved the flight control problems, according to two sources.
KNKT said the pilot was qualified on the 737 MAX 8 but did not say what airline he worked for or what role he played in assisting the crew.
The cockpit voice recording from that flight was wiped during maintenance undertaken before the plane's final flight, investigators said.