It also means that the aircraft will have to be re-designed and re-classified before it ever flies again (it's now a very clear design error, not a training or communication error)
It seems they tried it but MCAS kicked 5 seconds after they turned on the electrical trim. They didn't have enough time to correct the stabilizer. I don't know how fast returning a stabilizer to neutral position can be done, but they probably thought they had more than 5 seconds. They were probably going to turn off electronic trim control afterwards.
Really there should just have been a separate cutout for MCAS itself, but that would have triggered retraining requirements, so Boeing wanted to avoid that. But very simply, there should just be an 'off' switch to disable this system if it starts to run away, distinct from the whole runaway trim procedure.
(as well as 2-of-3 redundancy on the sensors, the lack of redundancy is seriously exacerbating the rate of incorrect MCAS system activations)
Well, not quite: if they wanted it to protect against stalls at very low altitude, it would be operational with flaps extended.
The faulty AoA sensor is causing the plane to think it’s about to stall and therefore MCAS works as designed to prevent the pilot from putting the plane into a stall.
Of course the design is wrong because the plane is actually pointing toward the ground and MCAS thinks it’s pointing to the sky...
Maybe a bit like a self driving car planes will eventually have a system where they can use visual markers as a check on what sensors are reporting.
The 737 max was designed to not be any different to fly than previous 737s, so adding a button to disable this system was not allowed as I understand it.
As these two tragic accidents have made clear that specification was pretty wrongheaded...
Besides adding the AoA disagree light AND having MCAS use a triple AoA sensor vote to determine the AoA angle.
MCAS is disabled while flaps are extended. It would have activated the second they retracted the flaps.
[0] Appendix 1, 05:40:30 (You can see the AND command being canceled by the pilots manual electric ANU command)
- Boeing will lose 10s of billions of dollars because of this in damages, lost contracts, and redesign costs.
- Their CEO will resign.
- The FAA will revamp many procedures to vastly increase certification costs and not allow these types of same-class-rating bullshit.
- The FAA or similar EU agencies may slap some fine against Boeing
- The families will sue and win a large settlement.
- One or more engineers may commit suicide. (which would be itself tragic)
- Middle management will pay zero or nearly zero price.
- No one will be internally fired by Boeing as the problem is systemic.
- No criminal charges.
Many of these things will only happen with a sustains public relations compaign against Boeing, congressional hearings, persistent news articles, documentaries highlighting the harrowing crash, etc.
EDIT: I’d say there’s a small chance even that a system called MCAS never flies again, even if that means the entire MAX concept has to be shelved.
If the MAX can fly without MCAS but just under a new type rating, that could be the way they go. Boeing simply has not been successful introducing computer-moderated flight controls and envelopes the way that Airbus has over the last decade (and those lessons were hard learned too).
>Back in September the European aerospace giant, which employs 15,000 people in the UK, was on the receiving end when it was found that billions of euros in low interest loans amounted to illegal subsidies.
>Boeing celebrated that moment as a comprehensive victory which would deal a mortal blow to Airbus and result in more US jobs.
>The reality is that neither of these companies can exist without government subsidies.
Both of these companies are strategic assets to the countries that have them. So no surprise here. I'm not even upset at it- it's realpolitik.
Their priority list is, AFAICT: 1. Find out what happened. 2. Find out why. 3. Find out how to make sure it doesn't happen again. 4. See point 3. 5. See point 3.
Not that I think that's going to be the result of step 2. It was a contributing factor, probably, but it's not the whole story by any means.
The ones I have read do not feature three-word explanations, but rather say things like "the chain of events that led to the accident could have been stopped at any of these single points: <seven items> and would also have been stopped if both a&b had been done, or if both c&d, or both c&e" and then discuss how each of the many might be changed. They don't say "five of the links in the event chain were at a profit-hungry corporation, whose CEO should be thrown in gaol, then they'll know to do that differently in the future".
"Runaway corporate greed" is fine reason for a quick and angry post on a social network, but aviation postmortems are a different kind of beast, heavy on analysis and prevention, light on anger.
This postmortem must include "runaway corporate greed" absolutely. Not sure what can be done about it as the FAA is not trustworthy anymore.
The engineering fix is obvious, but management is the problem.
It is certainly within the realm of possibility that there will be severe consequences, up to and including criminal charges.
Boeing's bottom line would like this is be crew or operating procedure.
Let me get you up to date:
"The deal — four years after the 2008 collapse of Lehman Brothers nearly brought down the financial system — was criticized at the time, raising concerns about whether some banks had grown too big to face criminal indictment."
"Citing anonymous officials close to the case, the New York Times reports that federal prosecutors spent months debating whether to issue criminal indictments for money laundering. Authorities eventually ruled it out as such charges could ultimately cost HSBC its charter to operate in the US, seriously undermining the country’s fragile economic recovery."
https://www.nytimes.com/2017/12/11/business/dealbook/hsbc-us...
[...Quebec Premier François Legault said that SNC-Lavalin was one of ten publicly-traded companies headquartered in Quebec that the province considers to be "strategic" and therefore in need of protection from a takeover that would force the company to leave the province....]
https://en.wikipedia.org/wiki/SNC-Lavalin#SNC-Lavalin_affair...
In similar condition (nose down) in other plane just pulling the stick would work but with MCAS you have shut it down using some switch and just the stick won't work.
And now the report is saying even that switch doesn't work? That one MCAS goes bonkers there's essentially no recourse?
It is as ludicrous as it sounds.
Are they talking about manual electric trim, or physically moving the trim wheel with its handle?
I would expect manual electric trim to stop working after you STAB TRIM CUTOUT, since that kills the trim motor. Did the pilots try physically moving the trim wheel?
And, the crew left the power setting at climb throughout almost the entire sequence, so they oversped the airframe.
And, when they (against procedure) (apparently) turned the electric trim system back on, they did not use the yoke manual trim switch to fix the nose down trim problem -- which is a big mystery.
The MCAS design inhibits its FCC trim down output when manual trim is utilized. So, if they had just continuously pushed the nose up manual trim switch on the yoke until they got the trim to neutral, then pulled the cutout (either the first time or second time), the accident could have been avoided.
History shows this is not a good human factors design on the part of Boeing, but the crew does not look good, either, IMO.
The EAD/service bulletin doesn't talk about sufficient nose up trim or caution against performing the cutout with even a slight mistrim.
> And then they did not work the mechanical trim wheel hard enough to reset the residual nose down trim.
It's possible that aerodynamic load (of the stabilizer opposing the elevator) made it physically impossible to manually trim given any mistrim at the time the cutout happened, given the airspeed they had. And, the captain is pulling back on the yoke as hard as he can, so he's unavailable to let go of it and grab a trim wheel instead without immediately losing altitude.
> And, when they (against procedure) (apparently) turned the electric trim system back on
It seems sensible to assume -- and the report states -- that they did this because they found that manual trim was impossible in these circumstances.
Which really under explains the situation. In reality the STAB TRIM CUTOUT must be switched to CUTOUT within 5 seconds of using the electronic stabilizer trim, or the MCAS will re-establish the forces.
Its been noted in previous discussions that while it would be difficult, the load can be overcome if both pilots were to operate the manual trim wheel at the same time.
Not that its a good situation to be in.
I haven't seen that noted anywhere, and have seen it theorized as impossible without motor assist, given their airspeed and with the elevator opposing. Got a link?
Excessive airloads on the stabilizer may require effort by both pilots to correct the mis-trim. In extreme cases it may be necessary to aerodynamically relieve the airloads to allow manual trimming. Accelerate or decelerate towards the in-trim speed while attempting to trim manually.
https://www.pilot18.com/wp-content/uploads/2017/01/B737NG_FC... page 312 (8.16)
It's also from a 20 year-old manual, and isn't present on newer manuals, and pilots haven't trained on it in decades. Not appropriate to expect pilots to know, and possibly not helpful here: the pilots were low altitude, so allowing the nose to drop even further (to relieve aerodynamic load) may have been deadly too.
Vne is where things start to get scary because it's usually based on flutter, which can catastrophically damage/destroy the aircraft in very short order.
I believe that's correct given that they had an Unreliable Airspeed Indicator warning (due to the malfunctioning AoA sensor), per the memory items on the UAI checklist.
It makes the forces on the trim wheel much worse, which explains why they couldn't turn it, but it's the correct checklist response to the conditions observed, and the Boeing/FAA directive completely failed to take the impact of this response into account.
The idea that a pilot would knowingly leave thrust at climb power while in modestly level flight at low altitude and expect not to overspeed is very strange to me, checklist or no checklist.
I think they were too busy fighting the controls to worry about that.
Note IAS DISAGREE alert:
"In the event of an uncommanded horizontal stabilizer trim movement, combined with any of the following potential effects or indications resulting from an erroneous Angle of Attack (AOA) input, the flight crew must comply with the Runaway Stabilizer procedure in the Operating Procedures chapter of this manual:
- Continuous or intermittent stick shaker on the affected side only.
- Minimum speed bar (red and black) on the affected side only.
- Increasing nose down control forces.
- IAS DISAGREE alert.
- ALT DISAGREE alert.
- AOA DISAGREE alert (if the option is installed)"
About which was written here:
https://leehamnews.com/2019/04/03/et302-used-the-cut-out-swi...
"the high speeds observed" ... "were logical. It’s a consequence of following the Emergency checklist for “IAS disagree” (IAS is Indicated Airspeed, i.e. the dynamic air pressure experienced by the aircraft) after takeoff."
In short, seeing that Boeing indeed wrote about the IAS alert being activated when the sensor fails, and MCAS gets activated, I can only conclude that Boeing indeed knew that the pilots would make the plane uncontrollable if they followed Boeing's instructions. It seems they just gambled on the chance that the second crash won't happen so soon after the first.
Either that, or we'd have to believe that what a single pilot manage to do for his Youtube video a company which is to deliver the planes in worth of hundreds of billions (!) of USD wasn't able to do.
Why? Because your instruments disagree about your airspeed. You want to have a large margin to keep your speed high enough that you won’t accidentally stall while you try to establish what’s reliable.
You can't point at a memory item and treat it like the pilots can only apply what's in there in exclusion to everything else. The structural limits of the aircraft are there for a reason.
Aside from anything else the pilots were trying to maintain altitude by their communication with ATC.
Not that I'm blaming them. I think they had too much going on to even consider moving the throttles, and thats 100% on Beoing, but it probably didn't help their chances of recovery.
But aerodynamic forces can conspire to make it very hard or physically impossible for human force to rotate it if the elevator is being used to combat the stabilizer at high speeds. See here for more discussion of the physics behind it: https://www.satcom.guru/2019/04/stabilizer-trim-loads-and-ra...
Counter-intuitively, letting go of the stick in brief increments might have been the correct move. Letting the nose pitch down would take force off the jackscrew and let both pilots crank hard on the stabilizer. Boeing manuals once covered this, but apparently they haven't since the 1980s, and their directive after the Lion Air accident made no mention of the necessity of such a procedure. Also they were only 7,000 feet above the ground so whether or not they'd have recovered in time is hard to say. Quite possibly the MCAS had already doomed the flight.
No, it's worse: the origin airport is at 7000ft elevation. They only had around 1000ft height AGL for all of the flight. So I agree that releasing the elevator at all seems surely suicidal.
Still damn close to the ground to be comfortable letting the plane dive.
https://www.flightradar24.com/blog/flightradar24-data-regard...
I guess we will have to wait for the final report but the pilot's actions are perplexing here. Even if we accept that they can't trim with the wheel, why enable electric trim and then not use it? Why not enable it, trim to where you want, and then use the cut out switch again?
They couldn't land with the stabilizers mis-trimmed. If the wheel wouldn't budge, re-enabling it and trimming electronically was the only option likely to occur to them, since the only other possible option (release the column, let the plane nose down so that the forces on the screw ease and they can trim manually) is completely counter-intuitive and was removed from Boeing's documentation and simulator training 30-40 years ago and was not covered in the FAA/Boeing MCAS directive.
> Even if we accept that they can't trim with the wheel, why enable electric trim and then not use it?
They did use it after re-enabling it. They just didn't re-disable it within 5 seconds of their last input manual electronic trim command, so the MCAS ran again a final time.
Whether that's because they just didn't get to the switches in time, weren't aware they had such a short window to do so (the FAA/Boeing bulletin does a piss poor job of communicating this), or were just so thoroughly overwhelemed by everything that was going on is hard to say at this point.
They could have just kept flying. They weren't in any immediate danger and had time to reach out for help. Worst case scenario, you fly straight for the next 30 minutes while ascending to 20-30k until you figure out what's going on.
>They did use it after re-enabling it.
Not really. The barely blipped it. Not what I would expect if they had a clear intention to re-enable electric trim in order to get the trim to where they wanted it.
The stabilizer's trimmed down. The pilot is repeatedly requesting the co-pilot's assistance in maintaining elevator trim up, and says to the co-pilot at 05:43:04 that the pitch is not enough to keep the plane level. They're well above Vmo at this point.
Per the Seattle Times coverage, a Swedish pilot simulation of the conditions could barely control the column to stay level: https://www.seattletimes.com/business/boeing-aerospace/boein...
> In the test, the two European pilots in the 737 simulator set up a situation reflecting what happens when the pre-software fix MCAS is activated: They moved the stabilizer to push the nose down. They set the indicators to show disagreement over the air speed and followed normal procedures to address that, which increases airspeed.
> They then followed the instructions Boeing recommended and, as airspeed increases, the forces on the control column and on the stabilizer wheel become increasingly strong.
> After just a few minutes, with the plane still nose down, the Swedish 737 training pilot is exerting all his might to hold the control column, locking his upper arms around it. Meanwhile, on his right, the first officer tries vainly to turn the stabilizer wheel, barely able to budge it by the end.
They're absolutely not climbing 14,000 feet in that condition. The control forces on the column in this situation are absurd. Their arms couldn't have held them level for more than a few minutes max.
Retracting the stabilizer was their only option.
If I'm reading the charts right it took them about a minute to go from 5,000 to 7,000 feet. So even if they hold on for just a few minutes more they're almost to 14,000 feet.
And you're taking speculation based on assumed facts too seriously. If they were struggling to keep the plane level then their simulation was different. In reality the plane was climbing all the way up until they enabled the electric trim and MCAS kicked in.
So must be manual trim wheel movements.
This entire report is frankly terrifying.
It's interesting that the flight with three pilots in the cockpit survived.
One thing that I've wondered though as I've read more about MCAS. MCAS can't kick in till the flaps are fully retracted. Usually when something goes wrong in response to an action, the response is to undo the action. Why isn't the procedure or even the pilot instinct to re-extend the flaps when the nose down occurs just after having retracting the flaps?
When the two AoA sensors began to disagree during takeoff, the left and right side airspeeds started disagreeing as a result. That leads the pilots to execute the Unreliable airspeed indicator checklist memory items, which include levelling off for troubleshooting and leaving the flaps in their current configuration (retracted), and to keep thrust high to avoid stalling due to the unreliable airspeed indicators.
It's precisely at this point that MCAS now kicks in and starts nosing them down. Extending flaps will cut it back out but: 1) they're now instinctually fighting the stabilizer with elevators to stay out a nose dive, 2) the checklist they were running when this started says not to extend flaps, 3) the Boeing/FAA directive tells them to hit the STAB CUTOUT, so they do that, but 4) the elevator/stabilizer fight + the high speed from the thrust being set to climb due to the checklist they were running when this started results in so much force on the manual stabilizer crank that the co-pilot can't turn it by hand and now they're so engaged in this stabilizer fight and trying to get the plane trimmed for landing that the flaps are the last thing on their mind, and the Boeing/FAA directive never instructed them to try re-extending them, airspeed disagree be damned. They're completely out of the manual and FAA/Boeing directive at this point. Nothing covers this (anymore, 30 year manuals would have had a procedure to ease the forces on the wheel here).
So lacking any other means of trimming for landing, they turn the electronic stabilizers back on, and trim electronically, which works...but they don't cut it again within 5 seconds (the FAA/Boeing directive didn't really spell out how crucial this timing is, or even consider that manual trim would have been made impossible by everything else going on), and the MCAS runs again, and the dive becomes fatal.
Because the story that I heard is that he purposefully commanded max pitch knowing that alpha protection would prevent the airplane from stalling, as his landing speed would be lowest at max AoA.
> I was commanding for more, pulling back full aft on the stick and the flight control computers prevented me from getting more lift therefore we hit harder than we would have (...) It turns out there's a little-known software feature known only then to a few Airbus software engineers, and to no pilots to no airlines that was the case. It's called a phugoid mode. And it was not the way we were trained the airplane should work, apparently it is the way the airplane does work. But that was not apparent to us.
https://aviation.stackexchange.com/questions/52147/why-cant-...
It's a truism of stocks that they move opposite of what you would expect when the final result comes in, and that's because they have already moved when news of whatever it is is released.
Eg: Company announces we will get 1 billion cash for free, stock goes up. when they actually get the cash, stock will go down.
Replace that scenario with whatever is making news about the company (mergers, new sales, personal changes, etc, etc).
The pilots didn't do that at all. Sustained manual trim only occurred after MCAS kicked in again at 5:40:27 and the pilots still waited before invoking the trim up command. The pilots never invoked sufficient trim up to counteract the automatic trim down command. Again, there is a reason the trim controls are on the control yoke in the first place. Of the three major MCAS trim down commands the pilots only stopped the second one with manual commands after it had already pushed the nose dangerously low. If the pilots had simply invoked manual trim promptly and counteracted the erroneous trim manual trim would have been successful after invoking a STAB CUT out.
If you think the pilots are following procedure why at 05:41:46 did: "the Captain ask[ed] the First-Officer if the trim is functional." ? That doesn't make sense, of course the trim doesn't work, the STAB TRIM cut out switches were engaged! But the response by the first officer was that "The First-Officer [has] replied that the trim was not working and asked if he could try it manually." which again doesn't make sense. But it gets worse because this happened a FULL MINUTE after the stab cut out switch was engaged, which means that neither pilot tried to manually trim the aircraft during that time at all!
But it gets better: "At 05:40:27, the Captain advised the First-Officer to trim up with him. " Which again doesn't make sense because it wouldn't make any difference if the both pilots were trimming up or not, the stabilizer doesn't move any faster.
My conclusion is that the pilots didn't know the checklist but its hard to tell because the CDR isn't presented completely.
This is very damning to Boeing. It's precisely the procedure they prescribed and intended to mitigate possible MCAS caused trim runaway. In light of the fact that they put this in place as a justification for moving the engines forward without reclassifying the plane, I don't see how they can get around fault here.
What a tragedy.
I can't imagine the emotion those pilots must have felt after attempting to do exactly what they were told to do to keep the aircraft in the air, only to have the nose lurch back downwards. Godspeed, gentlemen. It wasn't your fault.