But that's exactly what's disingenuous about the GP's claim. Many disasters do indeed involve a sequence of mistakes of different sorts but that's not really the case here. The situation with 737 max was one terribly system and the pilot's complete inability to stop this - inability that could have been anticipated and which was the product of the original bad design.
"His point is that these accidents are science's illegitimate children, bastards born of the confusion that lies within the complex organizations with which we manage our dangerous technologies."
This kind of disaster certainly can happen but the situation with the 737 Max was Boeing pushing an old design far beyond it's limits because of the threat of losing market share and regulators allowing this.
MCAS is a badly designed system, but many other stabiliser control failures could cause the aircraft to rapidly lose altitude. The solution is the same in all cases - flip the cutoff switches to disconnect automatic stab control and trim the stabiliser manually using the wheel on the center console.
The flight crews in both MCAS-related disasters showed serious failures in airmanship and a lack of understanding of the fundamentals of flight. They were taken by surprise by MCAS, but they should have been more than capable of swiftly handling that situation; their inability to do so is symptomatic of broader failings in the training and culture of pilots in many emerging markets.
https://www.nytimes.com/interactive/2018/11/16/world/asia/li...
https://www.nytimes.com/2019/09/18/magazine/boeing-737-max-c...
ET302 tried this-- maybe slightly late, but MCAS is weird/sneaky. Still, it's hard to fault their response at this point.
They were unable to budge the trim wheel because of overspeed. They were barely climbing at Vmo. This left them in a difficult position.
Ideal response would be to reduce power (prevent overspeed), keep climbing at Vmo. During this, try to turn trim wheel. If necessary, once they had sufficient altitude, they could aerodynamically unload and trim. Instead they, for some reason, decided to turn the stabilator trim system back on (whoops 1), and then used it an insufficient amount to get trim to a reasonable place (whoops 2), and then left it on for MCAS to trigger again (whoops 3).
You accuse me of being disingenuous and immediately follow it with a false claim.
This is untrue. Stabilator trim can be turned off. Indeed, before Lion Air 610 the previous flight had experienced the problem and had dealt with it correctly.
Also, re-trimming using the trim switch disables MCAS for some number of seconds.
In the case of ET302, they turned the system off, but allowed the aircraft to overspeed and were, as a result, unable to retrim manually. Still, they had a positive rate of climb. It is only when they turned it back on in violation of training/checklist and inexplicably did not use it to retrim nose up that they were doomed.
> This kind of disaster certainly can happen but the situation with the 737 Max was Boeing pushing an old design far beyond it's limits because of the threat of losing market share and regulators allowing this.
I strongly disagree. I think it's a badly engineered system but things like this are part of the normal design refinement that happens when planes are stretched and iterated upon. The 737 has bad handling on pitch during departure; bigger, more powerful 737's have it worse, and it makes sense to fix this.
In this day and age, I'm suspicious and annoyed even small effort to improperly spread blame when that spreading serves powerful interests.
Either approach is wrong: just pointing to the pilot and saying "hah-hah error" without considering what led to the error is what aviation did for decades. "Crash less!" we said to pilots, and were surprised when things didn't improve much. But you can't ignore crew performance, either.
The crews that crashed did not do great. But if a system is regularly putting crews to the test in a way that requires high levels of personal performance to survive, that's a bigger problem.
And MCAS is more easily improved than the rest: we can more easily reduce the frequency and severity of that "testing" than we can improve all flight crews. But we shouldn't ignore the problems in crew decision-making, and the related training choices (e.g. not requiring crews to demonstrate handling of runaway trim in some jurisdictions).
Not necessarily fair since one didn't even know what they were up against, and the other was trusting a Boeing checklist that wasn't guaranteed to work, and only stood a realistic chance at working if the failure did not occur at a critical stage of the flight, where a currently undocumented maneuver could be performed. (The 'roller coaster' by which the pilot allows the plane to dive to unload the stabilizer so it can be trimmed)
>And MCAS is more easily improved than the rest: we can more easily reduce the frequency and severity of that "testing" than we can improve all flight crews. But we shouldn't ignore the problems in crew decision-making, and the related training choices (e.g. not requiring crews to demonstrate handling of runaway trim in some jurisdictions).
This is just poppycock, if you ask me.
MCAS was a desperate attempt to satisfy a prescriptive behavior requirement (FAR 25.173, demonstration of longitudinal stability) during which the plane should not experience slackening control forces all the way to the stall in a wind up turn, which non-compliance with would disqualify the airframe from certification under the grandfathered 737 type certificate and as a Civil Transport Airplane.
There would have been no need to consider the skill of the pilots if due diligence and proper redundancy concomitant to the actual hazards of the design had been done, which weren't due to management's pressure to get this damn plane flying on time at any cost.
Well, it did get them back to positive rate climb, didn't it? :P Just, dubious subsequent actions gave that back.
> This is just poppycock, if not straight up, grade A bullshit; no personal disrespect intended to you, fine sir.
Well, it is absolutely personal disrespect, and adding qualifiers amplifies rather than undoes it. A decent person should do better.
> There would have been no need to consider the skill of the pilots if due diligence and proper redundancy concomitant to the actual hazards of the design had been done, which weren't due to management's pressure to get this damn plane flying on time at any cost.
I already said MCAS is awful, kthx? At the same time, it's exposed that many air crews in developing countries don't know how to deal with trim runaway. And trim runaway happens: switches get stuck. So the other links in the failure chain should be dealt with, so that they don't conspire to bring down aircraft under other conditions.
In the Lion Air penultimate flight, the situation was handled thanks to a third pilot in the cockpit with no other responsibilities contributing extra attention and reasoning. This is not available on every flight, and should not be considered a proof of safe operability. The mental model of a pilot unconcerned with the immediacy of flying the plane is more accommodating to unconventional occurrences due to being removed from the majority of learned perspective.
>Also, re-trimming using the trim switch disables MCAS for some number of seconds.
It also resets the activation cycle, and increments the amount by which the trim is activated. Both these details were unknown to all pilots at the time.
>In the case of ET302, they turned the system off, but allowed the aircraft to overspeed
And did nothing wrong. Given the stage of flight the problem occurred, they left the throttle in exactly the position they should have. Addis Ababa is also a "hot & high" airport, meaning the engines were already in the uppermost range of their operating envelope anyway. Furthermore, when the AoA sensor went bonkers, that leads to an airspeed unreliable checklist due to bad AoA figures throwing off the airspeed indicators which are dependent on AoA being correct for calibration. The airspeed unreliable checklist requires advancing throttles to the appropriate setting for the current stage of the flight regime, which was climb out.
>...and were, as a result, unable to retrim manually. Still, they had a positive rate of climb. It is only when they turned it back on in violation of training/checklist and inexplicably did not use it to retrim nose up that they were doomed.
They turned it back on in the hopes that the electronic trim could overpower the aerodynamic load where they could not, they did not realize that closing the circuit would give at most five seconds before MCAS dove again. Also, by this point, they were out of checklist.
It is almost as if I've heard these arguments before. (I have. We discussed it long ago when most things were conjecture.)
Sibling poster is correct. We've worked through this, and the pilots really couldn't have done any better considering the amount of information there was out at the time.
Also, later on, Boeing also notified airlines that only the MAX 10 I believe should be used in hot and high airports. The MAX 8 could take off due to Addis Ababa's extra long runway, but it just goes to ram home how uncomfortable a margin the Engineering firm was with safety margins afterwards.
It's basic airmanship to know that if you are not in climb attitude, that high power is going to overspeed in anything slick. Combine that with "overspeed" alerts and you should maybe realize it's time to pull the power back.
> They turned it back on in the hopes that the electronic trim could overpower the aerodynamic load where they could not, they did not realize that closing the circuit would give at most five seconds before MCAS dove again. Also, by this point, they were out of checklist.
They turned it back on, clicked the trim switch briefly, and then left it alone, despite knowing they were way out of trim. Can you explain why this makes sense? Why turn it on and not get back to nominal trim?
Also, they were still climbing at Vmmo (or overspeed). It would have always been an option to climb a bit...
Specifically it's the argument in the article that large disasters often have multiple causes. "Perrow says, Murphy's Law is wrong—what can go wrong usually goes right. But then one day a few of the bad little choices come together, and circumstances take an airplane down. Who, then, is really to blame?"
In large disasters, sometimes several not very likely simultaneous failures happen at the same time.
"The ValuJet accident is different. I would argue that it represents the third and most elusive kind of disaster, a "system accident," which may lie beyond the reach of conventional solution, and which a small group of thinkers, inspired by the Yale sociologist Charles Perrow, has been exploring elsewhere—for example, in power generation, chemical manufacturing, nuclear-weapons control, and space flight. Perrow has coined the more loaded term "normal accident" for such disasters, because he believes that they are normal for our time. His point is that these accidents are science's illegitimate children, bastards born of the confusion that lies within the complex organizations with which we manage our dangerous technologies. Perrow is not an expert on commercial flying, but his thinking applies to it nonetheless. In this case the organization includes not only ValuJet, the archetype of new-style airlines, but also the contractors that serve it and the government entities that, despite economic deregulation, are expected to oversee it."