Boeing Announces Update to 737 MAX Software as More Countries Drop the Banhammer

"ttyymmnn" (ttyymmnn) 03/12/2019 at 10:06 • Filed to: wingspan, Planelopnik

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As investigations continue into the cause of two crashes of Boeing 737 MAX 8 airliners in the span of just five months, Boeing announced that the company is working with the FAA to release a software update to the computerized flight control system that may have played a role in the disasters.

While no definitive causes have yet been identified, investigators are focusing their scrutiny on erroneous readings from the angle of attack (AOA) sensors on the nose of the airliner, and how those readings may have caused the airliner’s Maneuvering Characteristics Augmentation System, or MCAS, to command the airliner’s flight surfaces to lower the nose against the pilot’s wishes. In the case of !!!error: Indecipherable SUB-paragraph formatting!!! , which crashed into the Java Sea shortly after takeoff killing 189 passengers and crew, the two AOA sensors differed by as much as 20 degrees prior to takeoff. The false readings may have led the flight computer to believe the aircraft was in a stall condition during normal level flight. !!!error: Indecipherable SUB-paragraph formatting!!! , which crashed two days ago with 157 fatalities, displayed a similar flight profile and flew erratically shortly after takeoff before pilots lost control.

Though the 737 MAX 8 has drawn most of the attention since the crash of two such aircraft in just five months, the MCAS software that is the focus of the investigation, as well as Boeing’s upcoming software update, is present on the whole line of MAX aircraft, such as this United Airlines 737 MAX 9. (Tim Shaffer)

In a !!!error: Indecipherable SUB-paragraph formatting!!! on Tuesday, Boeing announced that it has been working with the FAA on a software fix for MCAS, and that the update would be released in the coming weeks.

For the past several months and in the aftermath of Lion Air Flight 610, Boeing has been developing a flight control software enhancement for the 737 MAX, designed to make an already safe aircraft even safer. This includes updates to the Maneuvering Characteristics Augmentation System (MCAS) flight control law, pilot displays, operation manuals and crew training. The enhanced flight control law incorporates angle of attack (AOA) inputs, limits stabilizer trim commands in response to an erroneous angle of attack reading, and provides a limit to the stabilizer command in order to retain elevator authority.

Despite assurances from Boeing, the FAA, and other regulatory agencies that the 737 MAX 8 is safe to fly, a growing number of airlines and governments have grounded the airliner until a fix has is in place. Following moves by Ethiopia and China to ground the MAX 8 yesterday, England, Australia, and Singapore followed suit today, brining the total to 15 countries that don’t want MAX 8s in their airspace. Vietnam, home to the privately-owned airliner VietJet, which has yet to enter the MAX 8 into service, has said that the government won’t certify the airliner until it is satisfied that fixes have been made. Operations in the US and other countries are continuing as normal while the investigation in to the crashes continues.

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You can find more stories about aviation, aviators and airplanes at !!!error: Indecipherable SUB-paragraph formatting!!! .

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Discerning > ttyymmnn 03/12/2019 at 10:13

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I have a flight coming up soon. Southwest, so of course everything is a 737. Thankfully it's the older 737-800

ttyymmnn > Discerning 03/12/2019 at 10:19

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Normally I would say that there are thousands of flights per day with the MAX fleet, and they aren’t falling out of the sky like dead moths. But I am concerned, though I am less concerned with a more experienced flight crew. You can bet that anybody flying the MAX right. now has had updated training, probably more sim time, and is very alert to any possible issues. 

facw > ttyymmnn 03/12/2019 at 10:20

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These two crashes are bad, but as a software engineer I’d be a lot less comfortable flying on a plane with a rushed patch than flying on one with rare bad behavior that a properly trained pilot should be able to override.

Highlander-Datsuns are Forever > Discerning 03/12/2019 at 10:22

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The great thing about SWA is they take off and land so many times a day they are very good at it.

ttyymmnn > facw 03/12/2019 at 10:24

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I think you hit it on the head. Especially now that we know so much more about what is going on, and I would wager that the airlines and pilots know more than we do.

I was struck, however, by this lead paragraph in story from today’s NYT:

Boeing is negotiating with the Federal Aviation Administration over improvements to its 737 Max 8 after the aircraft’s second crash in five months, though both the government and company insist the plane is safe to fly as is.

I understand how the system works, but negotiating? Here we see the exact problem with having a federal agency that is charged with both regulating and promoting an industry. The FAA should be dictating, not negotiating.

WilliamsSW > ttyymmnn 03/12/2019 at 10:35

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I was just thinking that all 737 MAX pilots should be getting sim time that includes MCAS runaway just now, but then it occurred to me that the sim maybe (probably) can’t do that yet (?). Trim runaway is something the sim can do, but it sounds like that’s a different procedure to override it.

I’d feel a lot more comfortable as a passenger if I knew that the crew up front had experienced MCAS runaway a few times in the sim, even without the changes.

And the fixes damn well better include reconciling the two AoA indicators *on the ground*, although that might not be as easy as it first sounds.  Right after takeoff is the worst time to have an MCAS problem.

Ash78, voting early and often > ttyymmnn 03/12/2019 at 10:41

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UPDATE SOFTWARE NOW?

[  ] YES

[X ] REMIND ME LATER

ttyymmnn > WilliamsSW 03/12/2019 at 10:41

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I had a brief email chat about this with f86sabre last night. To my uneducated brain, this sounds like a combination of bad sensors and software that doesn’t know what to do with bad data. AFAIK, the plane can be flown just fine with MCAS turned off. Which is not to say that pilots should do that (it’s only certified to fly with it, per JetStreamer) , just that they should be training to fly with it off and with the known nose pitch up tendencies. Investigators should be looking equally hard at the AOA sensor manufacturer , IMO. But Boeing also has a lot of egg on their face for a system that can be tricked into disaster by a single faulty sensor.

You can tell a Finn but you can't tell him much > facw 03/12/2019 at 10:42

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I get the impression the software patch has been in the works since the Lion Air crash, so hopefully that means it wasn’t rushed.

ttyymmnn > Ash78, voting early and often 03/12/2019 at 10:43

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Grindintosecond > ttyymmnn 03/12/2019 at 10:44

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Training. Training. Training. Experience x 3 as well. If Ethiopian Airlines is hiring 200 hour first officers, then they are asking for a slow if not incorrect response when things aren’t right. They have a great safety record, correct, however is that based on flight crews or mechanics and inspections done correctly?

Here’s the thing: The autopilot gets an incorrectly low airspeed fed to it, and it’s basic flight preservation logic (ANY airliner has this) says to dive to get the airspeed back., which as we can tell is not correct since it doesn’t know it’s flying just fine. I fly the max-8. We have procedures for an incorrect airspeed scenario. If the plane suddenly deviates from the path, hand fly it....flying the plane actually works!.....and then manage the scenario based on that. It’s based on engine setting and altitude and configuration. That’s just enough to get you somewhere to land safely.

Banning the plane over incorrect crew responses is just not the right thing to do either. Mostly because those countries have either a vested interest to make any american company look bad or don’t know how technology and crew concepts work (ahem, china?) 

Grindintosecond > Highlander-Datsuns are Forever 03/12/2019 at 10:45

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4,000 flights a day. They also hire people with quite a bit more than 200 hours flight time (Ethiopian)

ttyymmnn > Grindintosecond 03/12/2019 at 10:47

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Did you know about MCAS before Lion Air 610?

You can tell a Finn but you can't tell him much > ttyymmnn 03/12/2019 at 10:49

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It’s mind blowing how badly Boeing screwed up a safety critical system with their implementation of MCAS. You’ve got multiple AOA sensors because that is a safety critical piece of information. Why would you only use one of those sensors to feed information into a safety critical system? Generally speaking if you have a safety critical system with multiple sensors available you use all available data. That way your system compares the multiple data inputs and if one goes bad it utilizes the other data input and gives you an error.

Secondly that safety critical system has a failure mode that would appear to be nearly indistinguishable from a runaway trim failure. Why wouldn’t you program the flight controls so that the same action that stops a runaway auto trim system (pulling back hard on the yoke) would also stop a runaway MCAS system?

ttyymmnn > You can tell a Finn but you can't tell him much 03/12/2019 at 10:50

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Hubris? Desperation to get it certified?

Highlander-Datsuns are Forever > Grindintosecond 03/12/2019 at 10:51

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I think when my friend was hired he already was at >2,000 hrs commercial aviation .

WilliamsSW > ttyymmnn 03/12/2019 at 10:52

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All true, but what I was assuming   was:

- the aircraft isn’t airworthy without MCAS

- it doesn’t appear that airlines have been able to tell if MCAS is functioning properly on the ground

The 2nd statement sort of contradicts the first - how can you determine if the aircraft is airworthy? That’s a problem.

What I was suggesting was an interim fix only. Making the software failsafe is needed. 

Grindintosecond > Highlander-Datsuns are Forever 03/12/2019 at 10:58

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who with?

facw > You can tell a Finn but you can't tell him much 03/12/2019 at 11:03

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I’d imagine so, but I think it’s more than coincidence that Boeing wants to push it now. I’d imagine even if it has been in the works, there’s a fire under them to get it out sooner than they were originally planning (losing ~$30B in value will do that).

MUSASHI66 > ttyymmnn 03/12/2019 at 11:05

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So, Boing knows there is an issue as they are fixing the software

“Boeing announced that the company is working with the FAA to release a software update to the computerized flight control system that may have played a role in the disasters”  

Tons of countries and carriers revoke the flight certification, or won’t grant one.

“In a move that some see as more politics than safety, China was one of the first countries to ban flights by the 737 MAX 8"

“Following moves by Ethiopia and China to ground the MAX 8 yesterday, England, Australia, and Singapore followed suit today, brining the total to 15 countries that don’t want MAX 8s in their airspace. Vietnam, home to the privately-owned airliner VietJet, which has yet to enter the MAX 8 into service, has said that the government won’t certify the airliner until it is satisfied that fixes have been made. “

And then, although there were two crashes and Boeing admits some sort of a problem exists as they are working on a fix...

“Operations in the US and other countries are continuing as normal while the investigation in to the crashes continues.”

It seems to me the problem is political, but not on the Chinese side.

ttyymmnn > MUSASHI66 03/12/2019 at 11:11

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It seems to me the problem is political, but not on the Chinese side.

I do not disagree. As I said elsewhere in this thread, it demonstrates the conflict that can arise when a government agency is tasked with both regulating and promoting an industry.

I think scrutiny should also fall on the manufacturer of the AOA sensors. That said, it shouldn’t be possible for a single bad sensor to bring down an airliner. Nor should it be impossible for a crew to hand fly an airplane. 

MUSASHI66 > ttyymmnn 03/12/2019 at 11:17

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Agreed. I have just a passing interest in planes, but almost all the large incidents I can think of - the last two MAX 8 crashes, the big Air France crash a few years ago etc. - are due to faulty sensors/readings. To a complete newb like me, it seems this should not happen.

I understand how US government would want to protect such a huge industry, but I do agree that FAA should not be concerned about stock value as much as they should about safe skies. 

ttyymmnn > MUSASHI66 03/12/2019 at 11:33

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I scanned this list of commercial crashes , and over the last two years, I didn’t see any (other than these two recent disasters) that were the fault of sensors. Are you thinking of AF 447 ? That is definitely a crash that has come up in recent days, where an iced-over pitot tube gave the aircraft incorrect airspeed data and the crew reacted inappropriately.

Any time something goes wrong, we have to rely on the humans up front to resolve the situation. But humans are fallible, and emotional, and may not be able to keep their head. That’s what checklists are for. A Lufthansa executive said that the traveling public is not ready for a single pilot up front, nor should they be. We also aren’t ready for pilotless planes. If left to its own devices, the Ethiopian MAX 8 would have crashed immediately after takeoff. What we can’t have, and what I thought we would have learned by now, is airplanes that can overrule the pilot. There has to be a way to turn it all off and fly the plane.

Rusty Vandura - www.tinyurl.com/keepoppo > Grindintosecond 03/12/2019 at 11:42

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They have a great safety record, correct, however is that based on flight crews or mechanics and inspections done correctly?

Or a run of good fortune?

Highlander-Datsuns are Forever > Grindintosecond 03/12/2019 at 11:43

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I think he last flew with Mesaba, SAAB 340's, for around 6-7 years.

Grindintosecond > Highlander-Datsuns are Forever 03/12/2019 at 11:49

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He and i were in regionals at the dark age. Couldnt avoid being stuck for 7 years or more there.

MUSASHI66 > ttyymmnn 03/12/2019 at 11:51

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Yeah, I was thinking of AF 447. Pitot tube is a sensor which provided wrong data and killed hundreds. I guess I don’t understand how planes react to sensor input, and how many redundancies there are. But, to me, it seems like they aren’t doing it properly on the MAX 8. 

Highlander-Datsuns are Forever > Grindintosecond 03/12/2019 at 11:56

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IIRC he ended up paying his own way to get rated on the 737, then hounded the hiring managers until they they got hem on the list. I was making twice to three times his salary as a civil engineer until he got on at SWA as an FO.

Grindintosecond > Highlander-Datsuns are Forever 03/12/2019 at 12:46

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And that’s how it goes. It’s like doctors and lawyers. until the student loans get paid and residency’s are done, there’s no income till 35-40. So hes a bit more senior than I am at SW since he bought the type. I couldn’t afford it with a kid on the way back when they started hiring again so I kind of missed 5 years through the economy crunch. so when i got on, it was with 12k hours. I still feel late to the party...but....i’m at the party!

Highlander-Datsuns are Forever > Grindintosecond 03/12/2019 at 12:52

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Congrats, SWA sounds like a great organization to work for. My friend has been a captain for a few years now but still at the bottom of the ladder for captains. Got to get that Oakland base so you can do the 19 hr stay in Hawaii .

ttyymmnn > MUSASHI66 03/12/2019 at 13:58

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AF447 was just about the frozen pitot tube, though that was where the problems began. The situation got significantly worse when the flight crew failed to understand what was happening and didn’t act accordingly. This was exacerbated by a system in the Airbus where the movements of one pilot on the control stick is not reflected in the other pilot’s control stick. One pilot had the plane going almost straight up, and the other pilot didn’t realize that until it was too late. So again, it was a cascade of failures, but yes, it started with a bad sensor.

ttyymmnn > MUSASHI66 03/12/2019 at 14:28

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Just reread my comment. Should say AF447 was NOT just about the pitot tube. 

MUSASHI66 > ttyymmnn 03/12/2019 at 14:45

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It wasn’t, but it was where it all started. Sensor failure, and crew responding rather poorly. 

Grindintosecond > Highlander-Datsuns are Forever 03/12/2019 at 16:19

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that was a question i had for scheduling.....how long those stays would be. lol, as long as theres enough time for a mai-tai, i’m good with that.