A Lion Air jet that crashed last month should have been grounded over a recurrent technical problem and never permitted to make the fatal flight, Indonesian authorities .

The Boeing 737 MAX vanished from radar about 13 minutes after taking off from Jakarta on October 29, slamming into the Java Sea moments after it had asked to return to the capital.

The preliminary crash report from Indonesia’s transport safety agency did not pinpoint a definitive cause of the accident, which killed all 189 people on board, with a final report not likely to be filed until next year.

But investigators said that Lion Air kept putting the plane back into service despite repeatedly failing to fix a problem with the airspeed indicator in the days leading up to the fatal flight.

Its second last flight was from Denpasar in Bali to Jakarta.

“During that flight, the plane was experiencing a technical problem but the pilot decided to continue,” Nurcahyo Utomo, aviation head at the National Transport Safety Committee, told sources.

“The plane was no longer airworthy and it should not have kept” flying, he added.