Boeing Meets With Pilot Unions On MAX Questions

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Attempting to tamp down pilot concerns about its 737 MAX following the Lion Air crash, Boeing technical representatives met with at least two pilot unions this week. And industry sources say the company is considering a software revision to the airplane’s anti-stall autotrim system.

Lion Air JT610, a 737 MAX with only 800 hours on the airframe, crashed into the Java Sea off Jakarta on Oct. 29, killing all 189 people aboard. The Indonesian National Transportation Safety Committee released a preliminary report this week showing that the crew experienced continuous stick shaker activation shortly after takeoff due to a faulty angle of attack sensor. Because its engines are heavier and mounted farther forward, Boeing equipped MAX airplanes with an autotrim system called MCAS. It’s activated at high angles of attack and automatically applies nose-down trim as an anti-stall protection. Pilot unions have complained that Boeing didn’t document the existence of MCAS—Maneuvering Characteristics Augmentation System—and crews weren’t trained on it.

MCAS hasn’t been implicated in the crash, but the NTSC’s preliminary report showed that it was active during the crash flight and the pilots continually trimmed manually against its nose-down trim input. A previous crew that encountered the same problem addressed it through the standard runaway trim procedure, which is to use the airplane’s two stabilizer trim cutout switches to disable electric pitch trim. All models of the 737 are still equipped with manual trim wheels.

Boeing set up urgent meetings with pilot unions from Southwest and American Airlines, although what was discussed hasn’t been reported. “We were appreciative that Boeing reached out to us,” said Mike Trevino, spokesman for the Southwest Airlines Pilots Association, according to USA Today. A spokesman for the Allied Pilots Association, the American Airlines union, said the organization was looking for the Boeing outreach. “They brought in their A team,” said Dennis Tajer of APA.

At least one airline that operates the MAX, Southwest Airlines, says it’s discussing with Boeing the option of adding an angle-of-attack indication to the MAX’s primary flight display. Currently, the airplane has an AoA disagree flag that warns pilots if the two vane-type AoA sensors are providing inconsistent data. The option may be available on future MAX deliveries. Meanwhile, a report in the Daily Globe and Mail said Boeing may consider software revisions to the MAX, although the details weren’t revealed.   

Comments (7)

If the empty CG moved farther forward then wouldn't it be easier to recover from a stall? Why do they need this system for the forward CG situation?

Posted by: jvo fnr | December 1, 2018 11:52 AM    Report this comment

@jvo fnr, as I understand it, because of the new location of the engine nacelles they now produce lift when the aircraft is at high AOA. The concern is that in a situation where the AOA is increasing, the lift produced by the nacelles combined with nose up momentum can put the aircraft into a stall before the pilot can react with elevator.

Posted by: Mark Sletten | December 1, 2018 12:42 PM    Report this comment

"A previous crew that encountered the same problem addressed it through the standard runaway trim procedure"

So there is zero communication between flight crews, mechanics, and dispatchers.
WHO would dispatch a plane load of people just after a runaway trim problem?

Posted by: Mark Fraser | December 3, 2018 8:17 AM    Report this comment

"So there is zero communication between flight crews, mechanics, and dispatchers.
WHO would dispatch a plane load of people just after a runaway trim problem?"

Yes, they did communicate. The pilots discussed with maintenance the solution that maintenance performed to "fix' the so-called runaway trim problem. Except the problem was not runaway trim, it was the unknown MCAS system's interaction with the stabilizer trim.

We don't know why the last crew did not shut of the stab trim system as the previous crew did. But if the stick shaker activated right at take off, the crew's first reaction would be push the nose down. But in doing that you have an unknown system "helping" you push the nose down, then your next inclination is to arrest that excessive push forward with a pull on the yoke. And all of this happening close to the ground. I doubt if the crew really had anytime to go through any procedures while trying to keep the airplane from a rapid, repeated, and more aggressive nose over excursions repeated between 5 second intervals of the airplane responding to "up" trim and back stick.

The blame needs to be focused on Boeing just as tenaciously as on Lion Air's crew, maintenance, and dispatch.

As Paul's article states, American's pilot's union rep said Boeing brought in their "A" team in Boeing's attempt to "reach out" release speak for the big bucket of litigation crap Boeing has stepped into with unreported MCAS on board.

Posted by: Jim Holdeman | December 3, 2018 10:28 AM    Report this comment

Jim, please re-read the article.
They stated "faulty angle of attack sensor" that caused a stick shaker. That means:
-the mechanics either "fixed" the wrong thing between flights or did not test what they just replaced
-the new crew was surprised when the same even happened subsequently (and failed to do what the previous crew had done to correct it).

Yes it's easy now to Monday morning quarterback on that deadly flight in retrospect.
That's the point.
If the 2nd crew had the information from the previous crew....

Posted by: Mark Fraser | December 3, 2018 12:58 PM    Report this comment


Yes, that is what this article says. In addition, there are plenty other reports that point to other potential contributing issues including the aforementioned AOA sensor, the split readings between both AOA's, run-away-trim, airspeed discrepancies, etc.

All, some, or one of these issues can contribute to the intervention of the MCAS either directly or indirectly. The previous crew(s) dating back through the four previous flights had griped one or more of these issues with maintenance attempting to address them. Then the next crew talked with maintenance and agreed it was safe to fly. However, no matter what was changed, tested, and signed off, the next flight revealed similar problems.

I have done enough aircraft maintenance to understand you attack a problem based on the pilot complaint using the protocol demanded by the manufacturer's maintenance manual. You perform a maintenance task and then confirm that the task has solved the problem as per troubleshooting guides. If they all indicate problem solved, the only way to really confirm that is fly the airplane.

In this case, each succeeding flight seems to show Lion Air personnel did what the manual outlined. The problem for the maintenance people and the crew, no one knew there is another computer operated system that can contribute to the control issues including the stick shaker. It has been clear that there was communication between maintenance and the subsequent flight crews on diagnosis and repair to make a decision to keep flying the airplane.

In our Monday quarterbacking circles, let's look at all the evidence, as it is given to us, reserving blame and culpability after a clear determination of cause and affect. Too often, people make make judgement calls based on a pre-determined prejudices looking at or not looking at all the possibilities because of a that bias.

With 189 dead people, there is a lot of emotion generating blame at Lion Air and Boeing. If it lies squarely at the feet of Lion air so be it. However, if it lies at the feet of Boeing so be it as well. However, there is way more to this story with the complete truth yet to be told. This accident investigation should be as thorough on Boeing as it is on Lion Air.

Posted by: Jim Holdeman | December 3, 2018 2:00 PM    Report this comment

Well, we know for 100% for certain that a flight departed with a known issue (or at least untested fixes to that issue). Lets wait and see how that's Boeing's fault.

Posted by: Mark Fraser | December 3, 2018 2:36 PM    Report this comment

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