Contributing factors to the crash of the new Boeing jet, which killed all 189 people on board, included incorrect assumptions on how an anti-stall device called the Manoeuvring Characteristics Augmentation System (MCAS) functioned and how pilots would react, slides in the presentation showed on Wednesday.

Reliance on a single angle-of-attack sensor made the MCAS system more vulnerable to failure, while the sensor on the plane that crashed had been miscalibrated during an earlier repair, according to the slides.

Lion Air Flight 610 lost contact with air traffic controllers soon after take-off from Jakarta then crashed into the sea on October 29. The flight was on the way to Pangkal Pinang.

A Boeing spokeswoman declined to comment on the briefing, saying, "as the report hasn't been officially released by the authorities, it is premature for us to comment on its contents".

A Lion Air representative declined to comment.

The briefing slides said a lack of documentation about how systems would behave in the crash scenario, including the activation of a "stick shaker" that warned pilots of a dangerous loss of lift, also contributed.

The flight crew also faced multiple distractions and "deficiencies" in manual control of the aircraft and communication, the slides added.

The 737 MAX was grounded worldwide after a second deadly crash in Ethiopia in March 2019.

US plane maker Boeing is under growing pressure to explain what it knew about 737 MAX problems before the aircraft entered service, especially after a Reuters report on messages from a former test pilot describing erratic software behaviour on the 737 MAX jet two years before recent crashes.

Boeing has already said it would redesign the anti-stall system to rely on more than a single sensor and to help reduce pilot workload.

The plane maker is due to release its third-quarter financial results later on Wednesday.

Australian Associated Press