Boeing Company (BA)

[Porgie Tirebiter]

An AOA sensor had been replaced two flights earlier. It hadn't been tested properly for alignment. The last flight before the fatal one had experienced the exact same situation. A deadheading pilot from a different airline had been in the cockpit on that flight and had told that crew to use the stab cutout switches. But that guy wasn't aboard the fatal flight.

Below is a coy of the 737 FCOM addressing the issue. Everything above the dashed line are memory items. Step 4 would have saved both the Lion Air and Ethiopian crew and passengers. From the cockpit voice recorders we know that the crew in both crashes were busy looking through manuals in the minutes leading up to impact.