The Ethiopian Airlines plane that crashed last month nosedived several times before it hit the ground, a preliminary report has said.
Pilots “repeatedly” followed procedures recommended by Boeing before the crash, according to the first official report into the disaster.
Despite their efforts, pilots “were not able to control the aircraft”, Transport Minister Dagmawit Moges said.
Flight ET302 crashed after take-off from Addis Ababa, killing 157 people.
It was the second crash of a Boeing 737 Max aircraft in five months.
Last October, Lion Air flight JT 610 crashed into the sea near Indonesia killing all 189 people on board.
In a news conference in Addis Ababa, Ms Dagmawit said: “The crew performed all the procedures repeatedly [that were] provided by the manufacturer but were not able to control the aircraft.”
The 737 Max family of aircraft was grounded following the Ethiopian Airlines crash, a move affecting more than 300 planes.
The preliminary report did not attribute blame for the crash and did not give detailed analysis of the flight.
But it did suggest that Boeing review the aircraft control system and said aviation authorities should confirm the problem had been solved before allowing the 737 Max back into the air.
In a statement, the chief executive of Ethiopian Airlines, Tewolde GebreMariam, said he was “very proud” of the pilots’ “high level of professional performance”.
“It was very unfortunate they could not recover the airplane from the persistence of nosediving,” the airline said in a statement.
Investigators have focused their attention on the Manoeuvring Characteristics Augmentation System (MCAS) – software designed to help prevent the 737 Max from stalling.
The software reacts when sensors in the nose of the aircraft show the jet is climbing at too steep an angle, which can cause a plane to stall.
