Pilots from several airlines met with Boeing executives in Renton, Wash., on Saturday to discuss proposed changes to the 737 Max, two of which have crashed in recent months.
The meeting on Saturday, with about a dozen pilots and trainers, was part of Boeing’s effort to manage the crisis set off by the crash of Lion Air Flight 610 in October and the crash of Ethiopian Airlines Flight 302 under similar circumstances this month. Boeing and people briefed on the meeting confirmed it.
In addition to reviewing proposed modifications to new anti-stall software and cockpit displays, pilots from five airlines strapped into flight simulators to see how they would have handled the situation that is believed to have brought down Lion Air Flight 610 in Indonesia, according to two people briefed on the meeting.
In each case, the pilots using the simulators were able to land the plane safely.
Saturday’s session included representatives from American Airlines, Southwest Airlines and United Airlines — the three American carriers that fly the Max — as well as from two non-U.S. airlines, Copa Airlines and Fly Dubai. The group did not include representatives from Ethiopian Airlines, Lion Air or the large Chinese carriers that fly the 737 Max.
On Wednesday in Renton, where the 737 Max is assembled, Boeing will host a group of 200 pilots and officials from almost all the carriers that currently fly the Max or have ordered the jets. As on Saturday, Boeing plans to describe the proposed changes to the software, and review what new training procedures may be needed before airlines can once again fly the Max, which is grounded worldwide.
“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 said in a statement. “We had a productive session this past Saturday and plan to reach all current and many future Max operators and their home regulators.”
While Boeing continues to work on a software fix, American Airlines said it would extend its cancellations through April 24. American canceled nearly 90 of its roughly 6,700 flights a day because of the Max grounding.
International authorities and domestic regulators including the Federal Aviation Administration will have to sign off before the Max can fly again.
On Saturday, pilots from the five airlines simulated flights with the software as it was originally written, as well as with the proposed updates.
A leading theory is that the Lion Air flight crashed because the anti-stall software received erroneous data, forcing the plane into a nose-dive. The Ethiopian Airlines flight also crashed after an erratic takeoff.
In simulations using the current software, pilots were able to disable the anti-stall software using existing procedures, and land the airplane safely.
The simulations using the updated software required less intervention by the pilots.
The software, known as MCAS, is designed to push the nose of the plane down if it detects the plane pointing up at a dangerous angle that might induce a stall. To determine when it is needed, the software takes data from two so-called angle of attack sensors on the side of the plane, which measure whether the fuselage is pointing up or down.
But when it was originally designed, the software only responded to data from one sensor at a time.
Preliminary plans for a proposed update will change the software in several substantial ways, according to the people familiar with the meeting. It will take data from both angle of attack sensors, instead of just one.
If the difference between the two sensors is more than 5 degrees, the software will be disabled.
Instead of allowing the software to push the nose down multiple times, it will limit the number of instances it can attempt to push the nose down, and limit the duration of that intervention to 10 seconds.
On Sunday, Boeing also issued a statement on the equipment used to measure and display the plane’s angle of attack.
The New York Times reported on Thursday, that two of these indicators were sold as options.
Boeing previously charged extra for two features in the cockpit: the angle of attack indicator, which showed pilots the readings from the angle of attack sensors; and the disagree light, which notified pilots if the readings from the two sensors were at odds with one another.
Boeing will now make the disagree light standard in all new 737 Max planes, and will provide the indicator free of charge for customers who want it.
“All primary flight information required to safely and efficiently operate the 737 Max is included on the baseline primary flight display,” Boeing said. “All 737 Max airplanes display this data in a way that is consistent with pilot training and the fundamental instrument scan pattern that pilots are trained to use.”
The F.A.A. does not currently require pilots to to train on simulators that replicate all the features of the Max, and may not change that stance. But it is possible that even if the F.A.A. does not requires simulator training, other international regulators may do so.
“We’ve been working diligently and in close cooperation with the F.A.A. on the software update,” Boeing said in its statement. “We are taking a comprehensive and careful approach to design, develop and test the software that will ultimately lead to certification.”