Pilots in ‘deadly game of tag’ before fatal crash

Black box data shows that Lion Air pilots struggled to maintain control of a Boeing jet as its automatic safety system repeatedly pushed the plane’s nose down, according to a draft of a preliminary report by Indonesian authorities investigating last month’s deadly crash.

The investigators are focusing on whether faulty information from sensors led the plane’s system to force the nose down. The new Boeing 737 MAX 8 plunged into the Java Sea on October 29, killing all 189 people on board.

Information from the jet’s flight data recorder was included in a briefing for the Indonesian Parliament. Indonesian authorities were due to release the findings today but not to draw conclusions from the data.

Peter Lemme, an expert in aviation and satellite communications and a former Boeing engineer, wrote an analysis of the data on his blog.

The MAX, the latest version of Boeing’s popular 737, includes an automated system that pushes the nose down if a sensor detects that the nose is pointed so high that the plane could go into an aerodynamic stall.

Lemme described ‘‘a deadly game of tag’’ in which the plane pointed down and the pilots countered by manually aiming the nose higher, only for the sequence to repeat about five seconds later. This happened 26 times, but the pilots failed to recognise what was happening and follow the known procedure for countering incorrect activation of the automated safety system, he said.

Lemme said he was also troubled that the crew of the fatal flight apparently weren’t warned that similar problems had occurred on previous flights, and that the Lion Air jet wasn’t fixed after those flights.

Boeing said last week that it remained confident in the safety of the 737 MAX and had given airlines around the world two updates to ‘‘re-emphasise existing procedures’’.