Lion Air crash: Jakarta Boeing 737 'had prior instrument error'

[MT]

^The US Airforce did experiments with reverse raked wings. This was inherently instable and required active electronic management of some of the control surfaces. This is kind of along the lines of what I am thinking that MCAS was actually made to do... to make faster than human adjustments to reduce the effects of inherent instability. Unlike the reverse wing fighter jets, which had complete runaway instability, perhaps the change in engines created some undesired oscillations between 2 or 3 points of shared stability which were not fatal (until incorrectly MCAS'd) but uncomfortable.

Seams both US X29 and Sovjets SU47 got raked wing concept from Junkers Ju287 which all of them suffered from warping wings at certain flight conditions which a MCAS would not fix i presume.

[boffin]

But, because these sticks are not coupled and do not have any force feedback, the pilots did not know what the other one was doing.

This is something that has always struck me as an absolutely stupid design. If the plane has two sticks, they should absolutely be mechanically linked together, or only one set of controls should be active at a time, with a very obvious indication of which is active. I never liked the sidestick arrangement anyway, it just looks wrong, and seems like it would be awkward.

Actually in most modern passenger aircraft the left controls are connected to the left elevator, the right controls, right elevator and there's a sheer pin that can be broken (on purpose) if there's a jam, so that each side independently controls elevators; everything from roughly Dash-8 and bigger.  Egypt Air 990 was a case where this was highlighted in what appears to be pilot v pilot fight for  the aircraft.

[Gyro]

Standard airshow stuff for new planes. Light fuel load and a completely empty cabin. Even the passenger seats and cabin trim may be missing. Much bigger power to weight ratio than a normal commercial takeoff.

A long time ago, I flew in a British Midland 747 from San Diego to LHR. The aircraft had flown from LHR to LAX, then the little hop down to San Diego to drop off the last few passengers. It took off with about 30 passengers on board, and hardly any fuel. Whoosh....

I used to do a fairly regular trip to Cork airport from LHR. Cork is a small airport built on the top of a hill (you can't see one end of the runway from the other, subject to low cloud too). On days with unfavourable wind direction and speed (frequent) taking of from Cork used to involve bringing the tanker out, taking fuel off the plane (737) and using the short cross runway... Taxi right to the very end, turn without going onto the grass, full brakes, full throttle and release. As you say, "Whoosh...."

The plane would then fly to Shannon (much bigger, international flights), to fill up with sufficient fuel to fly back to LHR. I kid you not!

This was back in the '80s https://en.wikipedia.org/wiki/Cork_Airport

[djacobow]

It sounds like the MAX is inherently more prone to getting away from the pilot and stalling at high AOA maneuvers, and it harder to recover from, requiring much greater input to the elevator and less ability to add useful thrust?

Yes, I think this is basically true, but the caveat is that it gets unstable once you've already gotten it into a high AOA situation, which in normal ops should not happen. You might say that a pilot's #1 one job flying and airplane is keeping the wing flying, so this defect -- that the plane is a problematic performer at high AOA -- is perhaps less of an operational defect than it seems.

Essentially, without electronic help, the MAX has less maneuverability.

Again, this is not an airshow stuntplane, it's maneuverability at high AOA isn't generally that important, because it's not supposed to be there. And indications so far from these accidents is that the plan did not have high AOA when the problem kicked in. A faulty sensor made it *think* it was experiencing high AOA.

If a pilot is pushing a passenger jet carrying 200 people to the utmost limit, you'd think he has a really, really good and really, really imminent reason... like to avoid hitting something (including the ground).

History has shown it both ways. Sometimes a pilot correctly pushes a plane beyond its safe envelope because of good reason that requires it, sometimes pilots have caused accidents by doing so.

[djacobow]

The problem in 737Max case is that MCAS kicks in and starts quietly adding downward trim before the stick shaker angle of attack. And as far as I know this only this happens in manual flight mode. This was poorly explained to the pilots who's first reaction would be to countermand that input with opposite trim with the trim hat on the yoke. That apparently is not the way you disable MCAS and it keeps on fighting your inputs.

I'm not quite certain of this, but I believe in the Lionair case, the published data show that the stick shaker was going on one side. I haven't seen the ET data yet. I'd be surprised if MCAS before the stick shaker kicks in, but there's a lot surprising in these accidents.

[G7PSK]

It can take off like a Vulcan bomber:

Now that really was something to experience! I remember an airshow at RAF Finningley when I was a kid, back when they were still fully operational. One gently cruised in at low level and then, half way along the runway, just sat on its tail and went up almost vertically. The feeling of my chest being forcibly compressed completely overwhelmed the indescribable roar.

It left a lasting impression even after all these years, I've never experienced anything like it again. That level of noise exposure would never be allowed these days of course.

Sorry, OT.

P.S. I saw its last airshow at Yeovilton. Sadly, they were very gentle on the airframe and engines, they did deploy the parachute though.

I used to have workshop 400 meters from the main runway at RAF Marha,Marham Norfolk, all the air shows by the Vulcan bomber as the ground control officer was based there so I used to see the vulcan doing it's thing several times a year over about a 15 year period. Also saw and heard the Victor tankers taking off at all times of the day and night as with the Canberra's reconosance and the Tornado's, The noise level was so graet at times that it caused mortar to run down the walls, the engine run up area was less than 50 meters from my workshop. The only good side was the neighbors did complain about any noise I made at any time of day or night in the workshop.

[floobydust]

It's terrible to see engineers forced to either roll out unsafe shit, or lose their job.

The managers, executives etc. suffer little for their corruption, even when caught. One or two people might get fined or some jail time, despite hundreds killed.

Further proof is the way Boeing is handling things, as a "software upgrade" which doesn't even cover the AOA sensors having poor reliability in the first place.

[GeorgeOfTheJungle]

Further proof is the way Boeing is handling things, as a "software upgrade" which doesn't even cover the AOA sensors having poor reliability in the first place.

Wait, wait... perhaps it's not the sensors' fault, but a software bug.

[Gyro]

A storm is slowly but surely approaching Boeing, (https://www.theverge.com/2019/3/18/18270910/boeing-faa-investigation-max-8-mcas-trump)

...

Every time politicians, MBAs and managers meddle with technical issues something fails.

"... participated in phone conversations with top Boeing executives and other stakeholders, offering his thoughts on the aviation industry. But since then, he has faced criticism that his over-involvement stymied the FAA from acting sooner. "

Nooooooh!   

[floobydust]

Further proof is the way Boeing is handling things, as a "software upgrade" which doesn't even cover the AOA sensors having poor reliability in the first place.

Wait, wait... perhaps it's not the sensors' fault, but a software bug.

The AOA sensor is first in the chain of events, it triggers the MCAS software. Unless the flight control software has huge bugs...

MCAS I thought only activates in manual mode, and the prior complaints by two pilots had problems when autopilot was engaged, when MCAS should be disabled then.
Also, autothrottle did not work in one instance. This implies there's some other problem.

https://www.washingtonpost.com/business/economy/sensor-cited-as-potential-factor-in-boeing-crashes-draws-scrutiny/2019/03/17/5ecf0b0e-4682-11e9-aaf8-4512a6fe3439_story.html?noredirect=on&utm_term=.271f3763b148

[KL27x]

Even if there's no software bug, even if the AOA sensor is the most reliable sensor on the plane, there is an error in the design/implementation. If software bugs are also discovered, oh boy. Not that the engineers are the fault. Mistakes happen, and that is why the approval process (normally) takes as long as it does.

A storm is slowly but surely approaching Boeing, (https://www.theverge.com/2019/3/18/18270910/boeing-faa-investigation-max-8-mcas-trump)

Sure, Boeing is going to be "Shenzu Air" after Chinese investors buy it. J/K. They'll get a government bailout, if it comes to that. Maybe one scapegoat goes to jail for 2 years. But what about the FAA? Surely a bunch of those guys can be liberated from the federal payroll and offered some time behind bars for endangerment of human life if not bribery. And who knows how high up this goes into the government? Does it even end at the FAA?

[djacobow]

Even if there's no software bug, even if the AOA sensor is the most reliable sensor on the plane, there is an error in the design/implementation. If software bugs are also discovered, oh boy. Not that the engineers are the fault. Mistakes happen, and that is why the approval process (normally) takes as long as it does.

A storm is slowly but surely approaching Boeing, (https://www.theverge.com/2019/3/18/18270910/boeing-faa-investigation-max-8-mcas-trump)

Sure, Boeing is going to be "Shenzu Air" after Chinese investors buy it. J/K. They'll get a government bailout, if it comes to that. Maybe one scapegoat goes to jail for 2 years. But what about the FAA? Surely a bunch of those guys can be liberated from the federal payroll and offered some time behind bars for endangerment of human life if not bribery. And who knows how high up this goes into the government? Does it even end at the FAA?

You guys seem awfully sure that Boeing and the FAA worked together to sell an airplane they knew was unsafe. I'll agree, I think that if that is proven, the punishment should be very severe. But I think you do not need that kind of behavior to produce a bad outcome. I think it's interesting that so many people do. What incentive do either of those organizations have to certify a passenger killing machine?

[iMo]

Airlines want safety, but with margins so slim, they are forced to worry about their bottom line. And the FAA wants safety, but needs to weigh the Cost-Benefit of each new advance. So in the end, it is often Tombstone Technology and accidents -- that drive the industry forward.

[Marco]

Can there be a 737 Max pilot that does not know about MCAS and how to respond when it acts up anywhere in the world at this point?

Did Boeing actually send out mandatory to read information to airlines explaining the MCAS system after the first accident? Or would those pilots have to have followed the news, with all its inaccuracies?

If Boeing continued to pretend that pilots really didn't need to know there was an automatic control in a plane where pilots very much expect there not to be one, that's still on them.

[mtdoc]

Uh hu..

The 737 MAX Saga Is a Total Disgrace for Boeing and the FAA

This whole affair seems like a perfect microcosm for our twisted and broken modern U.S. economy and culture in general. Greed, regulatory capture and death — it has it all.

[MT]

Even if there's no software bug, even if the AOA sensor is the most reliable sensor on the plane, there is an error in the design/implementation. If software bugs are also discovered, oh boy. Not that the engineers are the fault. Mistakes happen, and that is why the approval process (normally) takes as long as it does.

A storm is slowly but surely approaching Boeing, (https://www.theverge.com/2019/3/18/18270910/boeing-faa-investigation-max-8-mcas-trump)

Sure, Boeing is going to be "Shenzu Air" after Chinese investors buy it. J/K. They'll get a government bailout, if it comes to that. Maybe one scapegoat goes to jail for 2 years. But what about the FAA? Surely a bunch of those guys can be liberated from the federal payroll and offered some time behind bars for endangerment of human life if not bribery. And who knows how high up this goes into the government? Does it even end at the FAA?

Mmkaay, now FBI with special counsel Miiuulleeerr and DOJ is setting up a investigation to Russian collusion as they suspect Piutin has caused the MCAS software bug. 2 years later no collusion was found and Miiuulleer refuses to release clown report while Dumpf having tea and cakes with Boing CEO..

[Kjelt]

Perhaps already posted, just in case:

https://www.eetimes.com/author.asp?section_id=36&doc_id=1334444

[Marco]

The Hudson river landing was a good example of why pilots need an internalized model of the flight system and why arcane rote procedures to deal with failures are not enough.

[SeanB]

I used to have workshop 400 meters from the main runway at RAF Marha,Marham Norfolk, all the air shows by the Vulcan bomber as the ground control officer was based there so I used to see the vulcan doing it's thing several times a year over about a 15 year period. Also saw and heard the Victor tankers taking off at all times of the day and night as with the Canberra's reconosance and the Tornado's, The noise level was so graet at times that it caused mortar to run down the walls, the engine run up area was less than 50 meters from my workshop. The only good side was the neighbors did complain about any noise I made at any time of day or night in the workshop.

OHS came around one day where I was, to measure sound levels. Coincidentally there was an Atar 09k50 in the test bed being given an after service check. Started, run till warm then the full power with full afterburner test while they were measuring sound pressure levels in the complex. 130dB plus, a half kilometer away from the test bed, and nobody noticed it as it was normal.

Now scary was when I accidentally got a flight in an aircraft that officially did not exist, and we needed all 4km of runway, plus a little more, to take off. Was a very interesting flight, but again, no cameras were allowed.

[djacobow]

The Hudson river landing was a good example of why pilots need an internalized model of the flight system and why arcane rote procedures to deal with failures are not enough.

This, I think is the first good argument I've heard for why 737 pilots need to know about MCAS.

As it happens, during the USAir 1549 landing, the A320's control systems did not let Sullenberger flare the way he had wanted to. The outcome was fine, but if the system had been more aggressive in "protecting the envelope" maybe it would not have been. At least he knew what the system would do.



But the thing is that flight manuals do not provide internalized models of how an airplane really flies. You have to get that from operating the machine. And furthermore, if you operate it carefully, within normal parameters associated with passenger flight, you won't get exposed to the extreme flight regimes where this knowledge is actually useful and important. So you can have 10,000 hours in a plane and still not know what it will do in an unusual situation. This *is* something you can learn in a simulator, if it is sufficiently faithful, and I think that is one learning that I think experts can already agree on regarding the MAX: the pilots should have gotten more sim time, including time that exposes them to the behavior of the aircraft in unusual scenarios that are specific to that model.

[james_s]

But, because these sticks are not coupled and do not have any force feedback, the pilots did not know what the other one was doing.

This is something that has always struck me as an absolutely stupid design. If the plane has two sticks, they should absolutely be mechanically linked together, or only one set of controls should be active at a time, with a very obvious indication of which is active. I never liked the sidestick arrangement anyway, it just looks wrong, and seems like it would be awkward.

Actually in most modern passenger aircraft the left controls are connected to the left elevator, the right controls, right elevator and there's a sheer pin that can be broken (on purpose) if there's a jam, so that each side independently controls elevators; everything from roughly Dash-8 and bigger.  Egypt Air 990 was a case where this was highlighted in what appears to be pilot v pilot fight for  the aircraft.

You're not likely to break that shear pin without knowing it though. On the Airbus planes the two sticks are not mechanically linked in any way at all, if one pilot is pulling back or pushing forward hard on their stick you wouldn't know by holding yours.

[KL27x]

Mmkaay, now FBI with special counsel Miiuulleeerr and DOJ is setting up a investigation to Russian collusion as they suspect Piutin has caused the MCAS software bug. 2 years later no collusion was found and Miiuulleer refuses to release clown report while Dumpf having tea and cakes with Boing CEO..

I like my tinfoil hats, so fair enough. But wait and see. FAA was fasttracking these approvals because someone was poking/pressuring them and or there was some major personal interest or incentive. Maybe Boeing hires retired FAA officials as consultants, and that is enough. Maybe there's more inbreeding and impropriety than that, even. I imagine Boeing is a very important company to our country's military and government.* And somehow many people were actively not doing their jobs and looking the other way.

*Transportation Secretary Elaine Chao even rode in a 737 MAX two days after the latest crash.

[Kjelt]

But the thing is that flight manuals do not provide internalized models of how an airplane really flies. You have to get that from operating the machine. And furthermore, if you operate it carefully, within normal parameters associated with passenger flight, you won't get exposed to the extreme flight regimes where this knowledge is actually useful and important. So you can have 10,000 hours in a plane and still not know what it will do in an unusual situation. This *is* something you can learn in a simulator, if it is sufficiently faithful, and I think that is one learning that I think experts can already agree on regarding the MAX: the pilots should have gotten more sim time, including time that exposes them to the behavior of the aircraft in unusual scenarios that are specific to that model.

That is the whole point is it not? According to that eetimes article Boeing claimed that any experienced 737 pilot did not need additional training or simtime for the max.
That is also why it was a big seller, the airlines did not have to invest in hours of training and that was a massive saving. It is also probably in the future the reason that if there has to be substantial additional training, the airlines will cancel their orders.

[KL27x]

But the thing is that flight manuals do not provide internalized models of how an airplane really flies. You have to get that from operating the machine. And furthermore, if you operate it carefully, within normal parameters associated with passenger flight, you won't get exposed to the extreme flight regimes where this knowledge is actually useful and important. So you can have 10,000 hours in a plane and still not know what it will do in an unusual situation. This *is* something you can learn in a simulator, if it is sufficiently faithful, and I think that is one learning that I think experts can already agree on regarding the MAX: the pilots should have gotten more sim time, including time that exposes them to the behavior of the aircraft in unusual scenarios that are specific to that model.

In this case, experiencing/simulating what the plane does in an extreme handling situation is not enough. They should need to experience what it is like not only when MCAS kicks in during the edge of stall. The training should also include the MCAS kicking in "out of the blue" during routine flight. This is a completely different experience with potentially very little time to react. If the plane pulls more than 1 negative G during this malfunction, it is going to be hard to even simulate. Reading a manual and sim might not even be enough, because of "instinctual" or automatic human response. Simulation is good, but now do it when you're cruising along with everything normal when the floor drops out from under you, you are disoriented, and the first and foremost thing being pressed onto your adrenaline soaked pea brain as you regain your orientation is the ground ending your life within the next 25 seconds unless you fix the problem within the first few of those seconds. And all the while you hear the screams of 200 passengers who are sure they're about to die through the cabin wall.

Military helicopter pilots are trained to evacuate the vehicle in a water crash, and the only effective simulation involves a giant tank of water and a fake helicopter that spins and dunks them upside down in the water. Apparently, only a small percentage of trainees make it out on the first try, even though they know exactly what is coming and when. This training greatly increased the survival rate of pilots in water landings. Simply knowing what to do and practicing under normal conditions did not help.

[djacobow]

But the thing is that flight manuals do not provide internalized models of how an airplane really flies. You have to get that from operating the machine. And furthermore, if you operate it carefully, within normal parameters associated with passenger flight, you won't get exposed to the extreme flight regimes where this knowledge is actually useful and important. So you can have 10,000 hours in a plane and still not know what it will do in an unusual situation. This *is* something you can learn in a simulator, if it is sufficiently faithful, and I think that is one learning that I think experts can already agree on regarding the MAX: the pilots should have gotten more sim time, including time that exposes them to the behavior of the aircraft in unusual scenarios that are specific to that model.

That is the whole point is it not? According to that eetimes article Boeing claimed that any experienced 737 pilot did not need additional training or simtime for the max.
That is also why it was a big seller, the airlines did not have to invest in hours of training and that was a massive saving. It is also probably in the future the reason that if there has to be substantial additional training, the airlines will cancel their orders.

Yes, that was the aircraft's goal and claim. And pilots are really trained these days to avoid the need for heroic mastery of ship's aerodynamics rather than trying to achieve such mastery. Today's pilots just don't have great stick and rudder skills, and that's turned out to be safe for the most part because other than trying to fly actually broken or malfunctioning aircraft, such skills rarely come up. They do, from time to time: USAir 1549, good outcome, AF447, bad outcome.

MCAS was designed to keep pilots from ever experiencing the instability of a MAX at extreme AOA. This was probably judged safer than trying to teach pilots to deal with it. Folks are saying that was not a sound engineering decision and I think they don't generally know what they're talking about. These are complex decisions, and history and human factors, and what can be expected of 1 std dev below mean pilots all figure into it.

But MCAS introduced a new failure mode (or modes) of its own, due to mistakes or poor enginneering, or reasons still unknown, and pilots have obviously not been able to handle that. The solution could be training on these failure modes or it could be fixing MCAS, or all of the above.