Clues have started to emerge Saturday from the examination of the black box recorders from the crashed Boeing 737 MAX 8.
A source that has listened to the air traffic control recording told Reuters: the Ethiopian Airlines .
Plane was traveling at an usually high speed after take off.
A voice from the cockpit made a request to increase altitude.
But then the pilot, who sounded very scared, made mention of a flight control problem and started to make a right turn to return to the airport.
The plane then vanished off the radar.
The team of investigators conducting the probe in Paris could not immediately be reached to confirm the conversation.
Similarities between the Ethiopian Airlines crash and the Lion Air flight over Indonesia in October have raised fresh questions about the systems on the 737 MAX.
So far there's no evidence to suggest software was to blame for either incident.
But Boeing is planning to release a software upgrade in the next week to 10 days, sources told Reuters.
All Boeing MAX jets have been grounded worldwide because of safety concerns.
Meanwhile, Ethiopian Airlines said Saturday DNA testing of the remains on the 157 passengers killed could take up to six months.
It's offered bereaved families charred earth from the crash site to bury .
Ethiopian minister of transport Dagmawit Moges says given the circumstances, identifying the remains will be challenging.
(SOUNDBITE) (English) ETHIOPIAN MINISTER OF TRANSPORT, DAGMAWIT MOGES, SAYING: ''Victim identification will be carried out using reliable, scientific and international standards and for this purpose, internationally-recognized and accredited organizations such as Interpol and Blake are going to be in the process." On Friday, investigators found a possible clue at the crash site: a key part of the plane's tail.
The horizontal stabilizer is reportedly set in an unusual position - similar to that seen in the wreckage of the Indonesian MAX 8.
The position of the stabilizer could help determine whether the plane was set nose down for a steep dive.
For bereaved families, answers can't come soon enough.