Indonesian investigators said on Wednesday that the Lion Air Boeing 737 jet that plunged into the sea, killing 189 people onboard, should have been grounded over a recurrent technical problem before it crashed on October 29.

Indonesian National Transportation Safety Committee released a preliminary report on Wednesday, using data collected from the jet's flight data recorder. The report says the jet's nose forced dangerously over two dozen times during the 11-minute flight. 

Investigators said Lion Air kept putting the plane back into service despite repeatedly failing to fix a problem with the airspeed indicator. 

"The plane was no longer airworthy and it should not have kept flying," Nurcahyo Utomo, aviation head at the National Transport Safety Committee said. 

What does the report say? 

According to the preliminary report, the pilots appeared to struggle with an automated system designed to keep the plane from stalling. The system repeatedly forced the plane's nose down, even when the plane was not stalling. Data showed that the pilots managed to pull the jet's nose back a total of 26 times from takeoff until it plummeted into the sea.

Aviation head at the National Transport Safety Committee, Nurcahyo Utomo, said the safety committee had not determined if the system failure contributed to the crash. 

Repeated safety problem 

Pilots flying the same plane a day earlier from Denpasar, Bali, to Jakarta had experienced a similar problem. 

"The flight from Denpasar to Jakarta experienced stick shaker activation during the takeoff rotation and remained active throughout the flight," the report said. It indicated that the conditions were considered un-airworthy and the flight should have been discontinued. 

The pilots reported the issue to Lion Air but the plane was approved for its final take-off the next day. 

Wednesday's preliminary report recommends that Lion Air must take steps to improve the safety culture.