JAKARTA, Nov. 28 (Xinhua) -- Pilot of Indonesia's Lion Air flight JT 610 was struggling to control the plane with faulty airspeed sensors and sent an urgent message to air traffic controllers before the crash that killed all 189 people on board, a preliminary report said on Wednesday.

The investigators from the National Transport Safety Committee (NTSC) examining the cause of the brand new Boeing 737 Max-8 jet recommended Lion Air improve its safety culture.

The report found that the pilot told air traffic controllers that the aircraft encountered a flight control problem shortly before it dove into waters off western Indonesia on Oct. 29, investigator of the NTSC Nurcahyato Utomo said.

"The captain sent an urgency message to the air traffic controllers that they are in a failure situation," he said.

The message was sent after the copilot complained that it was difficult to follow the instruction of "aircraft nose down" from the screen in the cockpit, said Nurcahyanto.

Just before the complaint, the pilot found out that the left speed indicator had a problem with a 20-degree difference from the right one after he compared with a standby instrument, the investigator said.

That confirmed the previous statement that the plane had a problem with the angle of attack (AOA) and speed indicator sensors.

However, the NTSC has not yet unveiled the definitive cause of the crash in Tanjung Karawang waters of West Java province, saying that it will keep searching for another black box, the cockpit voice recorder of the plane.

The report said that Lion Air has to ensure the operations manuals are complied "in a bid to improve the safety culture and to enable the pilot to make right decision to continue the flight," according to the investigator.

The Lion Air plane plunged into the sea 13 minutes after took off from the Jakarta international airport on a scheduled one-hour flight to Pangkal Pinang of Bangka Island on Oct. 29.