Looking at Lion Air Flight 610, all deaths could have been avoided given perfect communication about the fault: People familiar with the investigation reported

Looking at Lion Air Flight 610, all deaths could have been avoided given perfect communication about the fault: People familiar with the investigation reported that during a flight piloted by a different crew on the day before the crash, the same aircraft experienced a similar malfunction but an extra pilot sitting in the cockpit jumpseat correctly diagnosed the problem and told the crew how to disable the malfunctioning MCAS flight-control system. ... After the accident, the United States Federal Aviation Administration and Boeing issued warnings and training advisories to all operators of the Boeing 737 MAX series, reminding pilots to follow the runaway stabilizer checklist to avoid letting the MCAS cause similar problems. ... These training advisories were not fully followed, however, and similar issues caused the crash of Ethiopian Airlines Flight 302 on 10 March 2019, prompting a worldwide grounding of all 737 MAX aircraft.