Inside U.S. Airlines’ Decisions to Keep Flying the 737 MAX
by Scott McCartney
Ask chief executives what an airline’s first responsibility is and most will quickly respond that it’s safety. But that industry norm was challenged last week by the Boeing 737 MAX.
The CEOs of Southwest, American and United decided to keep flying the plane after the second MAX 8 crash within five months. Three days after the March 10 crash in Ethiopia, after much of the rest of the world had ordered the plane grounded, the Federal Aviation Administration changed course and grounded Boeing’s new version of the 737 in the U.S.
What appeared to some as hesitation raised questions of whether potential revenue loss and schedule disruption were placed ahead of safety at Southwest, American and United.
One CEO, Gary Kelly of Southwest, talked to the Journal about the process he went through last week to keep flying even as many customers and some employees expressed fears about the plane. The choice, he says, was whether to disrupt flights out of an abundance of caution or continue based on conclusions from the airline’s internal safety team.
“The only real factor that we were thinking about was safety,” Mr. Kelly says. “And then No. 2 was to get our customers where they want to go.”
Top leaders at American, which has 24 MAX 8 jets, and United, which was flying 14 MAX 9 planes, declined interview requests. American did provide two safety officials to discuss the airline’s decision to keep flying.
All three airlines say their decisions were largely data-driven. They routinely download thousands of data points from new aircraft like the MAX, and some began new monitoring to track performance of sensors suspected of contributing to the Oct. 29 crash of Lion Air Flight 610 in Indonesia.
The focus on data in aviation safety is seen as a major cause of improvement in the last decade or two.
But data don’t always capture the unknown, and just because an airplane hasn’t experienced a problem doesn’t mean it won’t have that problem in the future. Pilots routinely shut down systems suspected of malfunctioning and divert to the nearest airport or wait to take off until maintenance checks something. In aviation, there’s an adage: Better to be down here wishing you were up there than up there wishing you were down here.
In the case of the MAX, similarities between the crashes and other factors suggest some kind of problem. Boeing had identified deficiencies with its Maneuvering Characteristics Augmentation System (MCAS), new to the MAX, and was working on major software changes expected by the end of April.
Jim Hall, chair of the National Transportation Safety Board from 1994 to 2001, thinks Boeing and the FAA should have acted sooner to ground the plane. He says grounding by airlines would have been appropriate given the questions about MCAS, but not necessarily their responsibility.
“The prudent, responsible thing to do, if you actually put aviation safety first, would have been to ground the plane,” Mr. Hall says.
Financial questions didn’t come into consideration, all three airlines say.
Southwest’s Mr. Kelly says his internal, independent safety team was telling him that data collected from the MAX, which Southwest has been flying since 2017, showed no problem. (The airline flies 34 of those planes.)
And even if problems were to occur, Southwest pilots have been briefed on the system that was suspected of malfunctioning in both crashes and have routinely trained on steps to recover should the MAX’s computer mistakenly force the nose down. “These safety-management systems don’t speculate,” Mr. Kelly says.
Southwest, which has the largest U.S. fleet of MAX jets, also completed installation earlier this year of warning lights in its MAX cockpits that alert pilots if the two angle-of-attack sensors disagree, a sign one is failing. A faulty angle-of-attack indicator is suspected of playing a role in the Lion Air crash.
But with many customers calling on the airline to change flights booked on the MAX and some employees nervous as well, factors beyond safety data did come into play. At the same time, Mr. Kelly says he was also influenced by the FAA’s insistence, up until March 13, that the plane was safe to fly.
“There’s a science to it. There’s also art and just compassion as well. Absolutely all of that needs to be factored in,” he says. The process, he adds, “worked as designed.”
At American, officials say the same two factors Southwest saw convinced Chief Executive Doug Parker to fly on: data showing no problems and confidence pilots could handle any problems.
American had also been studying its MAX 8 jets more closely after the Lion Air crash, increasing analysis of data from monitors installed on the angle-of-attack sensors and the horizontal stabilizer, the part of the tail that moves to point the nose of the plane up or down.
No problems had shown up, says Neil Raaz, American’s director of flight safety. “We just didn’t see the indications that told us our airplanes were unsafe, and frankly, we still haven’t,” says Mr. Raaz, who is also a Boeing 737 captain and has U.S. Navy training in accident investigations.
But even if there are unknown problems with the MCAS system, American says it is confident pilots can recover because they train for similar problems. MCAS is supposed to push the nose of the plane down if it gets too high by moving the horizontal stabilizer, a panel used all the time to “trim” the airplane. The trim system keeps the plane level, or at a designated rate of climb or descent. The autopilot trims the airplane, or pilots can do it manually.
(Ethiopian Airlines has said its pilots had
new training for 737 MAX planes after the crash in Indonesia.)
If the MCAS system malfunctions, pilots say the prescribed fix is to use manual trim to stabilize the plane, and then disconnect the trim system. There’s a cutoff switch on the center pedestal of the 737, not far from throttles, marked “Stab Trim.” Pilots routinely train to disconnect the automatic trim in the case of runaway trim with autopilot use.
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Appeared in the March 21, 2019, print edition as 'Why the 737 MAX Kept Flying.'