Sriwijaya Air crew members salute to pay tribute to the victims of crashed Sriwijaya Air flight SJ 182 at the deck of Indonesian Navy hospital ship KRI Semarang in waters of Jakarta, Indonesia, Jan. 22, 2021. (Xinhua/Zulkarnain)

Indonesia's air accident investigator has sent five components of a crashed Sriwijaya Air jet to the US and the UK for examination, including the autothrottle that controls engine power automatically, the agency's head said on Tuesday.

The 26-year-old Boeing Co 737-500 crashed into the Java Sea shortly after takeoff from Jakarta on January 9, killing all 62 people on board.

National Transportation Safety Committee (KNKT) Chief Soerjanto Tjahjono told Reuters the components had been sent for examination to help find out why an autothrottle parameter had changed. 

He did not identify the other parts of the plane.

The plane's flight data recorder (FDR) has been found and read by investigators, but a maritime search is going on for the cockpit voice recorder's (CVR) memory unit that Tjahjono said would help explain any human factors behind the crash.

"If we only have the FDR, we do not know why the parameter changed, what was the reason," he said of the autothrottle. 

"We need confirmation from the components that we sent to the US and UK and the CVR," Tjahjono noted.

KNKT said in January it was investigating whether a problem with the autothrottle system contributed to the crash given an issue with it had been reported on a flight a few days earlier.

It is acceptable for a plane to fly with an autothrottle system that is not working because pilots can control it manually instead.

KNKT plans to issue a preliminary report into the crash soon, possibly on February 9, Tjahjono said.

Reuters