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Right around 37:30 it shows how difficult it is to use the manual trim wheel to affect the plane's attitude. One pilot has to move all focus to it, without tou
by mechhacker 7y ago
Right around 37:30 it shows how difficult it is to use the manual trim wheel to affect the plane's attitude.
One pilot has to move all focus to it, without touching the other controls.
It is still baffling to me how everything, from one sensor to a control system that can overwhelm the pilots with stick forces with no sanity checks in software, got through Boeing and then the FAA.
- nickpeterson 7y agoI think getting through Boeing was effectively the same as 'getting through' the FAA at this point though, since the FAA relied so heavily on Boeing in order to perform their stated duties.
- xeromal 7y agoDamn. Thanks for pointing that out. You can see the exertion he's having to apply. That's unsustainable over any long period of time.
- StreamBright 7y agoFAA is just another department of Boeing at this stage. See page 30 at 33.00 https://youtu.be/PlaMQBEg-9M?t=1989 https://youtu.be/PlaMQBEg-9M?t=1989
- ulfw 7y agoThey're not going to get me to sit in this shit plane again. Software update or not. I do not care.
- umvi 7y agoStatistically, sitting in a 737 Max is still safer than sitting in your car
- deleted 7y ago[deleted]
- Kiro 7y agoAll that argument has done for me (as a person afraid of flying) is to cause me to never sit in a car again.
- csommers 7y agoTrue, but I also know the Max has at least one serious design flaw. I don’t know the same about my car, which is why I’ll take it over a Max any day, and that’s why Boeing is having to PR themselves out of this mess.
- umvi 7y ago> I don’t know the same about my car, which is why I’ll take it over a Max any day "ignorance is bliss" If you knew how much software went into a car vs. an airplane, you might think twice. Airplanes seem more complicated than cars, but software-wise they are much simpler. Cars have millions upon millions more SLOC than airplanes. You think MCAS is bad, how about cars that have sudden loss of steering, emergency brakes that mysteriously engage, or a throttle that can't be disengaged? Serious design flaws in airplanes are these big dramatic events. Serious design flaws in cars pop up in the news every day, and we just ignore them [1][2]. [1] https://www.consumerreports.org/car-recalls-defects/mazda3-recall-sudden-unexpected-emergency-braking/ https://www.consumerreports.org/car-recalls-defects/mazda3-r... [2] https://www.consumerreports.org/car-recalls-defects/more-cars-recalled-due-to-faulty-takata-airbags/ https://www.consumerreports.org/car-recalls-defects/more-car...
- CydeWeys 7y agoSoftware flaws in cars are not nearly so catastrophic.
- umvi 7y agoCatastrophic as in 300 people will not die due to the flaw, yes. But one-off car fatalities that kill 1-3 people happen regularly and they add up. The self-driving variety pop up with the highest visibility but if you go searching you'll find tons of accidents where brake failure at highway speeds cause a fatal crash. I do concede that distracted driving and alcohol play a much bigger role in the large amount of car fatalities than software flaws. But I still stand by my original assertion that you are more likely to die due to the effects of a software flaw in your car than due to a software flaw in the 737 Max.
- mplanchard 7y agoHowever, given an accident occurring, you are much more likely to die in a plane than a car. Higher stakes, lower odds.
- FabHK 7y agoHowever, there are surprisingly many incidents without fatalities [1], and also quite some accidents in which a good percentage of people survive. [1] See http://avherald.com http://avherald.com for example.
- CydeWeys 7y agoBy what metric? Time spent in it? Passenger miles?
- simion314 7y agoSo if airlines would be forced to print the stats and if on your ticket for a MAX will be printed 100x more likely to crash then 737 classic would you chose MAX because some cars,bathroom or lightning statistics?
- umvi 7y ago> 100x more likely https://xkcd.com/1252/ https://xkcd.com/1252/ Zero 737 Maxes have crashed on US soil. The same cannot be said of other 737 types.
- ulfw 7y agoOnly the mighty US of A matters.
- umvi 7y agoMy point is that American pilots probably have an intrinsic advantage flying American-made planes over foreign pilots (it's the "white privilege" of the aviation world). It's hard to measure, but it's likely there in the form of pilot social circles.
- simion314 7y agoDid you read about Boeing and airlines trying to cut more of the pilots training costs? With the FAA in Boeing's pockets (if this accidents would not have happened) you would probably get less simulator training and more VR, tablet apps and software hacks to make even more money for the rich.
- velosol 7y agoI doubt it's the fact that they're American flying American planes as egregious accidents happen even in those sorts of scenarios (cf. Air France 447, French pilots, French plane, French carrier). There's the NY Times Magazine article that reminded everyone of the word 'airmanship' [1] although it wasn't terribly well-received [2], [3] by some other pilots. If you don't want to read all those, basically pilots in richer countries might be more likely to also be private pilots and more familiar with how an aircraft 'feels' that translates to a better sense of what's happening in larger aircraft. Combine a lack of that in poorer countries with the dumpster fire of Boeing's choices, crap replacement parts, and 'limited' training regimens and you have a fatal error chain forged. The criticisms focus on the idea that heroic pilots who could recognize and avoid the situation probably aren't the norm. Further, there's often prejudice against pilots from developing countries even when they are competent; neither of these excuse the systemic failure and getting to the conclusion of "but for the pilots the crashes wouldn't have happened" is somewhere between insulting and reductive. [1]: https://www.nytimes.com/2019/09/18/magazine/boeing-737-max-crashes.html https://www.nytimes.com/2019/09/18/magazine/boeing-737-max-c... [2]: https://medium.com/@elanhead/the-limits-of-william-langewiesches-airmanship-52546f20ec9a https://medium.com/@elanhead/the-limits-of-william-langewies... [3]: https://www.planeandpilotmag.com/explosive-new-york-times-story-lays-blame-for-boeing-737-max-crashes/ https://www.planeandpilotmag.com/explosive-new-york-times-st...
- dsfyu404ed 7y agoPer mile or per trip? My fleet sums to ~100k trips and zero (human) deaths. The 737MAX can't claim such a low number of deaths per trip. Regardless, we can choose our metrics to paint whatever picture we want to paint and any metric we choose is of little use anyway because it's an apples to oranges comparison.
- umvi 7y ago> My fleet sums to ~100k trips and zero (human) deaths. The 737MAX can't claim such a low number of deaths per trip. 737 Max had ~500K death-free trips before its first crash.
- cjbprime 7y agoThat sounds very wrong. According to https://randy.newairplane.com/2018/05/22/737-max-a-year-of-serving-the-globe/ https://randy.newairplane.com/2018/05/22/737-max-a-year-of-s... the Max had only made 41k flights total in May 2018, six months before the first crash.
- umvi 7y agoYes, I think you are right, it is much lower than 500K, I misread the wiki page which stated it had 500K flights at the time groundings started and assumed there weren't a significant number of flights between the first crash and groundings.
- cjbprime 7y agoI'm still not sure I follow. How many flights do you think the MAX has now? I'd guess around 100k but the wiki says around 600k and the difference seems important.
- Xixi 7y agoDid you actually run the numbers? The 737 MAX statistics are abysmal [1]. It stands at 3.08 crashes per million flights, compared to 0.06 for the 737 NG. It's two orders of magnitude worse. Are cars really two orders of magnitude more dangerous than planes? [1] http://airsafe.com/events/models/rate_mod.htm http://airsafe.com/events/models/rate_mod.htm
- umvi 7y agoAs another commenter stated, you can mince statistics any way you want to paint any picture you want. Only two 737 MAX have ever crashed (both outside of the US), so the 3.08 figure is an extrapolation, not necessarily reality. After the software update it might have gone another 500K flights (or more) without a crash, leaving the figure at 2.0 (or smaller). Let's say you need to travel from NYC to San Diego. Let's assume a car death rate of 1.25 deaths per 100 million vehicle miles (a figure that popped up in Google). But that includes motorcyles and pedestrians, so let's play it safe and call it 1 death per 100 million miles. By now we are comparing apples (chance of death by trip) to oranges (chance of death per mile traveled) but let's press on. Distance from NYC to San Diego is 2,800 miles. So your chance of dying en route to San Diego is about 1 * 2,800 / 100,000,000 or ~30 in a million chance if using a car. Whereas with the MAX it is ~3 in a million (if you take a direct flight), or an order of magnitude more safe.
- Xixi 7y agoIndeed I looked into it a little bit more and found that planes are about three orders or magnitude safer than cars [1] (fatality per miles traveled). So even assuming that the MAX is two orders of magnitude less safe than the 737 NG (based on limited data), it would still be an order of magnitude safer than traveling by car. [1] I found 11 fatalities per trillion miles for planes, and 12.5 fatalities per billion miles for cars (in the US).
- ulfw 7y agoBut how does travel per million miles make sense? Nobody decides to fly from Singapore to Sydney or drive. It's just not comparable. It's hard to find a good statistic that would make modes of transport comparable. But if I'd pick one I'd pick time spent (are 10 hours on a plane more or less safe than 10 hours in a car)
- deleted 7y ago[deleted]
- EdiX 7y agoThe trim wheel is the same as in every other 737, and it's one of the safest airplane types ever built.
- simion314 7y agoThe airplane is not the same even if some parts are reused,
- PedroBatista 7y agoFrom the 90s on what Boeing said, the FAA signed it.
- agumonkey 7y agoI can very faintly understand the reaction when Boeing was so successful. It just exemplify that no institution should rest on laurels and there should be mandatory external pressure and chaos monkey like systems to restore doubts.
- im_down_w_otp 7y agoThey have chaos monkey like systems all over the place when designing and building commercial aircraft. They perform tons of analyses like FMEA on their processes, their designs, then they have tons of SimIL/SIL/HIL testing partially derived from those analyses to verify their safety case, and at almost every layer of the development lifecycle they do tons of fault-injection oriented verification. The MCAS system went through an amount of rigor that dwarfs anything applied to typical software or IT infrastructure, but the issue persisted due to fundamental underestimation of risk associated with this kind of failure and a confusingly terrible design & implementation from a functional-safety and human factors perspective.
- agumonkey 7y agoThanks for the reminder, but I meant at a higher spot in the organization, clearly the FAA lacked verification, that's where I meant to add more.
- throwaway5752 7y agoAnyone old enough knows this is flows from 1980s Reagan deregulation policies. Now these same people (literally the same people, in some cases) are trying to blame the government for it. The government (FAA) is nominally at fault, but the reason they are at fault is exactly what you said - they could not get funding to do their job and relied on industry to self-regulate.
- CydeWeys 7y agoIt's controls designed in the 60s grandfathered in for many decades because of common type ratings that simply don't make any sense anymore. More modern clean sheet plane designs do not have the issue of literally not being able to apply enough force to adjust the trim! I think the mismatch may be that these are all-manual designs, and the 737 is much larger now than when it was first designed, plus the first design didn't have automated systems counteracting your inputs.
- kayfox 7y agoBoeing was looking to do a clean sheet design, the airlines wanted to keep the same type rating. The presentation micharacterizes that bit of history, but that's what was going on. This follows what made the A320neo popular, Airbus took a older venerable design and re-engined it for higher efficiency. The 777 got a similar upgrade that did include a new wing design. Ultimately Boeing is looking to introduce an all-composites design that fills the 737 and 757 roles, but airlines desires for crew commonality might push that back.
- gsnedders 7y ago> This follows what made the A320neo popular, Airbus took a older venerable design and re-engined it for higher efficiency. Though note the A320 is a newer design than the 737; the A320neo as a result didn't have the big problem of the 737 MAX: because its landing gear was always longer, because it was always designed for high-bypass turbofans, it could easily fit the larger engines under its wings without having to relocate the engine mounting. The 737 MAX is a world away from the original 737 (hell, the shortest 737 MAX is 6.6m/23% longer than the original 737 design!), whereas the A320neo is much, much closer to the original design. The 737 MAX has ~80% parts commonality with the previous-generation 737 NG, yet alone the original 737; the A320neo has 95% with its predecessor, which _is_ the original design.
- tyingq 7y ago"It's controls designed in the 60s" Probably even earlier. The trim wheels in the Boeing 707 look pretty similar to the 737.
- cjbprime 7y ago> One pilot has to move all focus to it, without touching the other controls. And even that may not be enough. It's quite plausibly physically impossible if the pilot happens to be less strong than this one, or if the aircraft's situation is worse than this simulator's. In particular, the Ethiopian flight was in extreme overspeed (if I recall, past the max safe structural speed for the plane!), which increases all of these forces. I'm not sure whether that was being modeled by the simulator, or if the simulation's model of trim wheel force is a correct one. There's certainly no guarantee that a pilot can produce the force required to relieve aerodynamic load on the stabilizer here. It's a purely mechanical system.
- _ph_ 7y agoActually, in earlier flight manuals for the 737 there was a description for the so called roller-coster-maneuver for exactly the case that the trim was so far off that it couldn't be operated manually any more. The maneuver consisted of pushing the yoke forward to take the pressure off the stabilizer and quickly trim back and then put the nose up again. So it was documented, that in certain conditions the forces could be too high for the pilots.
- lmilcin 7y agoThink of it for a sec. Your plane tries to kill you by pointing the nose down. With all your force you are barely able to make it only loose the altitude slowly. Now, would you point your nose down knowing that you may not be able to point it back up again?
- _ph_ 7y agoWell, the roller-coster maneuver assumes you are high enough up that you can trade off some of your height for correcting the trim. Here is a link to the description: http://www.b737.org.uk/runawaystab.htm#rc http://www.b737.org.uk/runawaystab.htm#rc This obviously wouldn't work in cases like the Ethiopian, where the plane had very little height over ground due to the high mountains around the airport. Edit: the point isn't that the maneuver had prevented the accident, but that its existance in the flight manuals shows that it was known that the trim forces could be higher than what the pilots could apply to the trim wheels.
- PunksATawnyFill 7y agoThis is what "self-regulating" looks like. We've seen it again and again: Industries do not "self-regulate." How many people have to die before the "REGULATION BAD!" people are put in their place?
- _ph_ 7y agoThe argument of Boeing for MCAS to be not "safety critical" is, that there is a trim cut out switch in every airplane, which is to be activated in case of a "trim runaway" to cut of all electricity to the trimming system, including MCAS. As this is a memory checklist, every problems should be able to just switch off MCAS in case of a problem... As mentioned in the talk, the problem is, that reality differs, and the MCAS actions don't appear to the pilot like a normal trim runaway. Actually, the day before the Lion Air crash, the machine already had the same problem, but the pilots (as the story goes due to the advice of a third pilot present) did activate the cut out switch and solved the problem. That still doesn't explain why Boeing didn't implement at least consistency checking with the other sensor. And of course, we know now, how wrong Boeing was in their assumption. Unfortunately the next day, the other crew did not do this. And on the Ethiopian Air flight, they did activate the cut out switch, but way to late and didn't regain control of the machine, as it was out of trim too far.
- kayfox 7y agoCorrection on the Ethiopian flight: They activated the trim cutout, were able to regain most control, and then deactivated it, presumably to adjust the trim, tested that they had trim controls, and then something happened to distract them from trimming it correctly and then cutting it back out. Had they left it cut out, they would have been able to keep it under control, had they adjusted the trim and then cut it out, they would have been in a decent position to come back and land. It will be interesting to see what the investigation finds about why it was cut back in and then left.
- xvf22 7y agoIn previous models you could cut out the auto trim while still having electric trim on the yoke enabled. Sadly in the MAX Boeing decided to get rid of this feature which would have been pretty damn useful for these crews.
- pps43 7y agoI wonder if rolling, then flying upside down for a while would have helped.
- dredmorbius 7y agoIt's ... within the realm of distant possibility. But generally not recommende practice. Flight systems (fuel feed, hydraulics) assume a gravitational vector toward the bottom of the aircraft. Flying inverted would starve fuel and hydraulic systems. https://outline.com/73xHvn https://outline.com/73xHvn