House Panel Lets Pilots, Airlines Discuss 737 MAX

A June 19 hearing of the House Aviation Subcommittee explored the perspectives of airlines, pilots, and other stakeholders on the Boeing 737 MAX.

Witnesses were:

  • Airlines – Sharon Pinkerton, Airlines for America (prepared testimony here);
  • Pilots – Dan Carey, Allied Pilots Association (American Airlines) (prepared testimony here);
  • Flight attendants – Sara Nelson, Association of Flight Attendants-CWA (prepared testimony here); as well as
  • former FAA Administrator (and former Air Line Pilots Association president) Randy Babbitt (prepared testimony here) and….
  • Chesley “Sully” Sullenberger (prepared testimony here).

Background: There have been two recent crashes of the 737 MAX (Lion Air and Ethiopian Airlines) that led to aviation safety regulators around the world, and finally the FAA, to ground the plane. Preliminary investigations reveal that in both accidents:

  • A failure of an angle of attack (AoA) sensor caused the pilot’s instruments to read that the plane was flying at a very different angle (measured as the plane of the wing vs the plane of the relative wind) than the copilot’s instruments told the copilot. (On one of the crashes it was a faulty sensor; in the other crash, the sensor was most likely taken out by a bird strike.) There are two AoA sensors (left and right) on the MAX and in both cases the left sensor failed while the right sensor remained accurate, but apparently the left sensor was the one in use on both occasions, and its failure triggered a correction system.
  • The sensor failure caused an automatic trim adjustment subsystem called MCAS (maneuvering characteristics augmentation system) to activate and try to adjust the angle of the plane automatically by activating stabilizers for short periods of time. The “stick shaker” haptic notification that a stall may be imminent was also activated, to make sure that the pilot instantly became alerted.
  • The MCAS system was new to the 737 MAX and was not explained in the flight manual, so pilots were likely unaware that the MCAS system was trying to adjust the angle of the plane.
  • In the previous model of the 737, one airline insisted on having Boeing install optional AoA indicator panels on both the pilot and copilot side as an extra feature. That airline later asked for the addition of an AoA “disagree light” that would light up whenever the sensor on the pilot’s side and the sensor on the copilot’s side were disagreeing, which would be an obvious indication that a sensor was probably faulty or broken. Apparently, for the MAX, the AoA disagree light became standard but somehow (Boeing and a contractor disagree on how this happened), the disagree light was never hooked up to anything unless the airline also wanted to install the separate AoA indicators, which few did.
  • In both the Lion Air and Ethiopian Air crashes, the pilots fought escalating automatic AND (aircraft nose down) actions forced by the MCAS system with manual ANU (aircraft nose up) trim adjustments, in varying ways (the Ethiopian crew turned the automatic system off for a while and then turned it back on; the Lion crew left it on), and in both cases, the aircraft oscillated up and down until diving and crashing.
  • Boeing is currently working on a fix for the MCAS software that relies on both the left and right AoA sensors and will shut down the MCAS system if the two sensors differ, and the FAA is testing that software fix.

Hearing. The airline representative was there primarily to discuss the economic impact of the grounding of the 737 MAX on U.S. airlines, provided stats on orders and deliveries of the 737 MAX for U.S. airlines through March 31, 2019:

U.S. Airlines That Have Ordered the 737 MAX
Already Scheduled 2020 and TOTAL
Delivered for 2019 Beyond ORDERS
Southwest 34 44 224 302
American 24 16 60 100
United 14 16 155 185
Alaska 3 29 32
TOTAL 72 79 468 619

But the vast majority of the discussion involved specific safety aspects of the aircraft and were handled by the three pilot-witnesses: Carey, Sullenberger, and Babbitt.

Carey made it a point to stand up for the flight crews of the Indonesian and Ethiopian airlines involved in the two fatal 737 MAX crashes. He particularly singled out Ethiopian Airlines for its long record of safety and pointed out that there are only four full-fledged 737 MAX simulators in the world, and one is in Addis Ababa. And in response to a question, Sullenberger said that “it’s unlikely that other crews would have had very different experiences or perform very differently than these two crews did on their accident flights prior to knowledge of this system…”

This is in contrast to the narrative being pushed by T&I ranking minority member Sam Graves (R-MO) and others who have tried to put the focus on the relative inadequacy of pilot training in foreign countries compared to the United States, with other countries using what Graves says is overreliance on automated systems instead of old-school stick-and-rudder flying techniques.

Sullenberger emphasized that there is no substitute for time in a simulator: “We should all want pilots to experience these challenging situations for the first time in a simulator and not in flight with passengers and crew on board. And reading about it on an iPad is not even close to sufficient. Pilots must experience it physically firsthand…It’s critical that pilots, as soon as possible, experience in a full motion, level D simulator and not just a part-task trainer…They need to develop a muscle memory of their experiences so that it will be immediately accessible to them in the future, even years from now, when they face such a crisis.”

Speaking of simulators, Babbitt told the subcommittee “I have had the opportunity to fly the Boeing simulator yesterday and I flew both scenarios of the old software and the new software. Obviously, this came after I turned in my testimony…I knew what the procedures were in the new system. And so I was able to follow the procedures but, essentially, I had training. I had been briefed as to what the reaction of the airplane was going to be and nevertheless, it is, as in any emergency, when a fire bell goes off in the aircraft…It’s quite disconcerting and one of the first things you do is stop the noise. In this case you can’t stop the noise. The stick shaker continues to go and we figured out, I mean, my experience in Boeing’s, we had one going and one not, that would tell you you’ve got an indicator problem. But, yes, the new software fix was, I think, a very good one. It obviously limits the amount of authority given to the pitch down and it only does it once. I mean, you either fix it or you don’t and it is a runaway stabilizer trim.”

Babbitt’s access to the Boeing simulator was a sore spot for Carey, who told the panel “Boeing invited two of our pilots who are here today who have a cumulative of over 5000 hours on the Boeing 737 aircraft to use that simulator on June 5. Shortly before that appointment, Boeing rescinded that invitation. So, it’s curious to me while Boeing is working on this fix, they don’t want the people who fly it to actually see it.”

Rep. Dan Lipinski (D-IL) asked the panel what changes they thought should be made in the FAA’s safety certification progress, particularly the “ODA” (organization designation authority) program where U.S. manufacturers can perform tests themselves, subject to standards set by the FAA. Sullenberger emphasized the need for robust FAA safety budgets and strict whistleblower protections and safety cultures in both the FAA and manufacturers.

Later, Rep. Dena Titus (D-NV) revisited the ODA issue to get Babbitt’s perspective. The former FAA chief responded that “The ODA process has been around since the beginning of time and…airplanes, I mean, the only pilots I know that didn’t go through it were Orville and Wilbur. Everybody else has had to turn over their designs as they wanted things certified and, you know, the process works. I mean, you simply don’t have the manpower to  absolutely, you know, watch every piece of design. Boeing has over 40,000 engineers, the FAA has 1,400.”

Sullenberger responded that “ODA is actually a fairly recent revision of the previous DER [designated engineering representative] system and one of the major changes in that is that the FAA no longer chooses their designees, they’re chosen by the manufacturer and so, again, the incentives are not aligned as consistently toward public good with those kinds of choices being made and depending upon who their supervisors are.


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