JAKARTA, Jan. 21 -- An investigator from Indonesia's National Transportation Safety Committee (NTSC) said Wednesday the preliminary report resulted from the investigation into the crash of AirAsia flight QZ8501 would be used for internal discussion inside the NTSC.

The investigator also said the announcement of the report depended on the NTSC chief. "The preliminary report would ultimately be used for internal discussions, matching it with opinions and findings of investigators involved in the investigation," NTSC investigator Sulaiman DA told Xinhua by phone.

He said that investigation into the flight data recorder (FDR) and the cockpit voice recorder (CVR) of the ill-fated passenger plane was still progressing at the moment. "We cannot predict when it (the preliminary report) can be done, " he added.

Citing the content of QZ8501 CVR recording, NTSC investigators said that the pilot was very busy attempting to regain control of the plane in the last minutes before the crash.

They brushed aside possible terrorist acts that may led to the crash, saying that there was neither voice of threat nor signal in the CVR and FDR that may indicate the plane was under terror threat or attack.

Indonesia said Tuesday that the crashed AirAsia flight QZ8501 climbed at an abnormally high rate and plunged suddenly before disappearing from radar.

Addressing the Parliament, Indonesian Transport Minister Ignasius Jonan said " it is not normal to climb like that. It is very rare for commercial planes which normally climb just 1,000 to 2,000 feet per minute."

"It can only be done by a fighter jet," the transport minister added.

What caused the flight to climb too fast remained unknown now.

Flight QZ8501, with 162 people onboard, plummeted into the Java Sea near the Karimata Strait during its journey from Surabaya to Singapore on Dec. 28.