A faulty automatic engine throttle system that was not properly monitored by pilots led to the deadly January 2021 crash of a Sriwijaya Co 737-500 jet, a final report by Indonesia's air accident investigator said on Thursday.

The crash into the Java Sea, which killed all 62 people on board, was Indonesia's third major commercial plane crash in just over six years and shone a spotlight on the country's poor air safety record.

Indonesia's National Transportation Safety Committee (KNKT) said investigators had found it difficult to analyse the situation in the cockpit of the 26-year-old jet because the captain's voice was not recorded.

KNKT said there had been no regulations and guidelines on upset prevention and recovery training by airlines that ensured a pilot's ability to help prevent unusual situations from occurring and recover from them in a timely manner if they did occur. Sriwijaya has since carried out such training for its pilots, KNKT said.