On November 6, Boeing issued an update to Boeing 737 MAX aircrews. The change, directed by the Federal Aviation Administration (FAA), came because Boeing had never provided guidance to pilots on what to do when part of an updated safety system malfunctioned—the very scenario that the pilots of Indonesia’s Lion Air Flight 610 faced on October 29. Not knowing how to correct for the malfunction, the aircrew and their passengers were doomed. All aboard were lost as the aircraft crashed into the Java Sea.

First approved for commercial operation by the FAA on March 8, 2017, the MAX is just beginning to be delivered in large volumes. Lion Air was one of Boeing’s primary foreign customers for the MAX, which is also flown by Southwest Airlines, American Airlines, and Air Canada. The Lion Air aircraft lost in the accident was virtually brand new, delivered by Boeing in August; this was the first accident involving an aircraft touted for its safety.

But Boeing never told pilots about one key new safety feature—an automated anti-stall system—or how to troubleshoot its failure. The manual update raised an outcry from pilots in the US.