On Saturday, Boeing met with pilots from several airlines to review changes to the 737 MAX’s MCAS software in preparation for a more public explanation of the alterations expected to remove the beleaguered airliner from its worldwide grounding. On Wednesday, Boeing is expected to bring together “pilots and officials” from the airlines with the affected 737s in their fleets.
In addition to reviewing the software, pilots from five airlines flew simulated failures of the MCAS and were able to disengage the system and safely complete the flight. The New York Times is reporting that pilots who flew the simulation with the original software had just 40 seconds to identify MCAS as the source of the trim movement and disable it. And it’s worth repeating that these pilots had been aware of the controversy swirling around MCAS since the Ethiopian Airlines crash this month.
According to reports, Boeing is set to confirm changes previously reported as considered, which include changing the MCAS configuration to accept data from both angle-of-attack sensors rather than just one, limiting the number of times the MCAS can drive the stabilizer to affect nose-down pitch, and limiting the duration of the events to 10 seconds. Preliminary reports from both the Lion Air and Ethiopian Airlines accidents suggest that the MCAS continually tried to offset the pilots’ efforts to level the aircraft. In addition, new coding will make the MCAS disengage if it sees a differential in AOA sensor readings of more than 5 degrees.
Those same pilots few the 737 MAX simulator with the revised software and were able to diagnose simulated failures and land safely with less effort, according to reports.
“This is part of our ongoing effort to share more details about our plan for supporting the safe return of the 737 Max to commercial service,” Boeing says. “We had a productive session this past Saturday and plan to reach all current and many future Max operators and their home regulators.”
Meanwhile, Southwest Airlines, the U.S. airline with the most 737 MAX aircraft in its fleet, is canceling approximately 130 flights a day, while American is canceling roughly 90 flights a day. Southwest has 4000 daily flights exclusively on 737s, while American has 6700 flights a day across a wide range of aircraft types.