You can see a picture of the wheel here:
https://www.quora.com/What-are-the-spinning-wheels-in-an-air...
The pilots would be very familiar with the sound and what it represents. The trim wheel also spins when the trim is running, a large and obvious indication (I posted a link to a photo of it).
> Boeing issued a multi-operator message (MOM) explaining the MAX’s manoeuvring characteristics augmentation system (MCAS) “commands nose-down stabilizer” in certain flight profiles using “input data and other airplane systems.” MCAS is operated by the flight control computer and “activated without pilot input and only operates in manual, flaps-up flight,” and MCAS is not part of previous 737 designs.
> The Allied Pilots Association (APA) told American Airlines (AA) pilots in a message on its website. “It is not in the AA 737 Flight Manual Part 2, nor is there a description in the Boeing FCOM. It will be soon.”
> A multi-page document issued by the airline’s flight operations department that highlights the differences between the MAX and 737 NG does not mention MCAS or any other changes to the auto-trim system.
> A multi-operator message (MOM) from Boeing on Nov. 6 cautioned that “an erroneous AOA” can trigger automatic nose-down pitch-trim.
There are lots on indications that at least in the Lion Air case it was not in manuals or communications to pilots.
Further here:
https://www.wsj.com/articles/boeing-withheld-information-on-...
https://outline.com/https://www.wsj.com/articles/boeing-with...
The pilot of the same airplane on the prior flight to the Lion Air crash did just that.
Pilots are given all this information and are meant to read it before takeoff but there is no way to enforce that.
Maintenance logs show the AoA vane was replaced, but Lion Air has a sketchy history with maintenance and what's written in the logs doesn't always reflect the reality, they are one of the cheapest airlines in the world and need to keep planes flying. I'd say that's likely the root of the issue combined with pilots not following the procedure books when faced with anomalous behavior.
https://www.airlineratings.com/news/lion-air-plane-fault-fou...
I hear you about runaway trim, but it seems that you are quite focused on the blades of grass and not looking so much at the lawn.
Nobody has given me an adequate answer to one simple question: what is the indicator the industry will use to determine when it has made the cockpits so complex that the complexity itself becomes a danger? Because we can play this game for a few decades more: manufacturers mod-up old planes with new software, extra training is added to the pilot's schedules, there are crashes where commenters in good faith can say "but that's an obvious part of any pilot's training". Repeat and rinse -- with the proviso that with each round the overall complexity continues to increase.
Technology developers, more than anyone else, are quite cognizant of the fact that we can create technology we ourselves cannot understand. Perhaps the aviation industry and the associated regulators somehow missed this?
The pilots are supposed to know how to deal with runaway stab trim. It doesn't matter why it was running away, just that the pilots know how to deal with it. Whether it was MCAS or the autopilot or a short circuit, does not matter.
After it is safely back on the ground, then the specific cause of the failure can be ascertained and corrected.
Let's take engine failure. When you're training twins, you're going to get one of the engines pulled on you quite a bit -- usually when you least expect it. That's because a lot of people died educating the industry to how important it is to be able to handle engine failure in all flight modes: takeoff, climb-out, cruise-climb, and so on. That reaction sequence has to be drilled into pilots to such a degree that there's no thinking involved.
But runaway trim? Seriously? Sure, you'll get the training, but in all modes of flight? Drilled into you until you can handle it in your sleep? No way. That's preposterous. We _thought_ we knew that those kinds of problems don't happen at weird times to cause people to die. So if you're flying along in cruise and you've got a runaway trim, somebody does a mental lookup -- which might take 3 or 4 seconds -- locates the breaker, then throws it. We do this other type of training a lot too, but there are tons of subsystems on your average commercial airliner. We don't train for that the way we train for engine failure. We've got huge reams of checklists in commercial cockpits dedicated to this kind of slower problem-solving.
So yes, in both cases a person could argue that training was either not given or not implemented by the crew. But that ignore the realistic limitations of trying to train crews on modern equipment. You simply can't do some kind of weird cross-tab grid where everything is trained everywhere and to the same degree. At some point the human factor has to come into play. People aren't robots. It looks like these accidents happened on takeoff/climb-out, one of the most busy and complex things a crew can do (not near the complexity of hand-flying the various instrument approaches, of course).
You gotta ask yourself: if I'm watching my turbine numbers, my airspeed, looking for traffic, the copilot's talking to the pax, and so forth? Would I catch a runaway trim right away? More to the point, if I missed it, would the ensuing chaos, _in some cases_ prevent me from being able to cognitively switch back to diagnostic mode? After all, we teach pilot when all else fails, fly the plane first. Add to that systems like MCAS that might exist in the software that the pilots are unaware of?
If these accidents turn out to be MCAS/runaway trim related, I would be interested in learning about the crew environment when it happened, specifically other issues taxing the pilots and whether or not the flight director was engaged.
So yes, sure. You can train your way out of this. At some point, however, you have to ask if the cost we're paying in lives is worth the lessons we're learning which all seem to boil down to "people are cognitively limited in many ways"
I'm sure the training issue will be prominent in the NTSB report.
Note that stall recovery is heavily trained, but airliners still crash because the pilot reflexively commands nose up in a stall instead of nose down. And the MCAS system is there to nose it down in a stall.
Not so. First: before Lion Air accident, nobody knew there is a new device that can move the controls that way under these conditions (in that phase of flight etc). The whole device was kept secret by Boeing. Second: the pilots had the trained reflexes what they are to do, and with these, there are more steps to try to overcome such movements before the decision to use the switch. And that’s exactly what the pilots did: attempted the steps before. Which seemed to help, but MCAS kept misbehaving. As the seconds matter, then it was to late.
The reason the stab trim cutoff switches are there is so the pilot can stop runaway trim. The switches are prominently placed.
I expect the failure of the pilots to throw those switches to be prominent in the eventual NTSB report on the accidents.
The second accident would be especially perplexing because surely the pilots would have known about the Lion Air crash. If I was a 737MAX pilot, I'd be keenly interested in other crashes in the same aircraft, so I could ensure it wouldn't happen to me. Wouldn't you?
The stabilizer trim motors are very powerful and do not need to be offloaded in order to work.
https://www.nytimes.com/interactive/2019/03/13/world/boeing-...
Have you seen the graphs? There are 20 seconds intervals. They “fight” the plane, then something (the investigation is still on what) makes it worse again.
That’s what confused the pilots: the misbehavior repeats after they think the plane returned to normal.
It's like if an engine is on fire, and I shut down the engine, and the fire goes out. There's no way I'm going to think "It's OK now, I can restart the engine." No way in hell.
However:
https://news.ycombinator.com/item?id=19420964
"pilots and aviation experts say that what happened on the Lion Air flight doesn’t look like a standard stabilizer runaway, because that is defined as continuous uncommanded movement of the tail."
"On the accident flight, the tail movement wasn’t continuous; the pilots were able to counter the nose-down movement multiple times."
"In addition, the MCAS altered the control column response to the stabilizer movement. Pulling back on the column normally interrupts any stabilizer nose-down movement, but with MCAS operating that control column function was disabled."
And do you really agree with the simplified interpretation like:
https://news.ycombinator.com/item?id=19424761
"two pilots fell out of the sky to their deaths and it simply never occurred to them to try pulling back hard."
I still believe that the way the airplane behaved in these two cases was exactly the opposite of what the pilots have been trained in their flights and in the simulators, and that the behavior was counter intuitive and unexpected to them and that that is the only reason they weren't able to save themselves.
Good UI is not trivially obvious. And it really makes a difference between the life and the death in certain use cases. And thinking about something in the safety of your armchair is very different from "having the plane that is doing exactly what you don't expect and then you die." The plane behaving the very way you haven't been trained in the simulations before.
Finally, I believe that all the issues reported here
https://www.seattletimes.com/business/boeing-aerospace/faile...
contributed to the manifestation that turned out to be deadly:
"The safety analysis:
- Understated the power of the new flight control system, which was designed to swivel the horizontal tail to push the nose of the plane down to avert a stall. When the planes later entered service, MCAS was capable of moving the tail more than four times farther than was stated in the initial safety analysis document.
- Failed to account for how the system could reset itself each time a pilot responded, thereby missing the potential impact of the system repeatedly pushing the airplane’s nose downward.
- Assessed a failure of the system as one level below “catastrophic.” But even that “hazardous” danger level should have precluded activation of the system based on input from a single sensor — and yet that’s how it was designed."
Interestingly and tangentially, the software people particularly like to blame the user. I've worked in many teams wit more people almost automatically dismissing any user input. But the users are, in fact, typically right in a sense that they often have the real world problems that are simply not recognized by the designers/developers assuming infinite knowledge and the infinite time the user has.
It could well be that it is obvious for anyone with the proper training, but then maybe not all airline pilots get the proper training? Or if they have the training but are pushed to hard in the name of cutting costs, and profits?
However, if it indeed was expected to be obvious to all pilots, why even - as I understand it - have the warning on the optional HUD?
Seems like bad safety engineering to have extraneous warnings possibly increasing cognitive load in a a crisis situation.