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FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

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Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#181

Post by ricardobeat »

jacquesgt wrote: post #85
cyberferret wrote: post #75

Earlier quoted context omitted.

Basic rudimentary 'stick and rudder' flying skills was a big factor in AF447's crash. All old school pilots know that when you aircraft is in a nose high stall condition, you never keep pulling back on the stick, but instead push it forwards to lower the nose and get the wings flying again. The fact that the co-pilot in question kept holding the stick to the back stops was the main reason that the aircraft wallowed i…

Part of the issue may have been that the plane had slowed down so much that the stall warning stopped (it disengages below a certain airspeed apparently). When he stopped pulling up, the plane sped up and the stall warning started again. Pull up again, plane slows down, stall warning stops.

I wonder if something about this system was changed after that incident - why not keep sounding the stall alarm if the plane ends up outside the flight/sensor envelope? Can’t you assume that it didn’t magically cross the stall zone back into normal flight?

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#183

Post by skgoa »

halter73 wrote: post #103
th0ma5 wrote: post #51

Earlier quoted context omitted.

To be fair, ignoring user input could have potentially have saved Air France 447... I mean I actually can't think of an automated fool proof system that would've fixed 447, but incorrect input was a major factor.

IIRC, the cockpit voice recording included a comment from one of the co-pilots about how pulling back on the yoke couldn't cause a stall. The assumption was that the Airbus's fly-by-wire system would prevent it and ensure the aircraft still climbed as long as the pilot held back on the stick. The co-pilot apparently didn't realize that the sensor issue that disabled the autopilot also disabled the stall prevention. A…

The copilot pulling the yoke back continued to do so, long after the other, much more experienced, copilot had formally assumed control and had attempted to bring the nose back down by pushing the yoke forward. Ultimately the inexperienced copilot fighting against his more experienced superior was what doomed the airplane. Both the senior copilot and the captain immediately identified the problem and attempted to take the correct action.

This is not a problem with how the system works, since this behaviour is explicitely communicated to pilots. It even says right on the instrument panel what control law the plane is in. There are only a handful of control laws and the differences aren't that complex. Anyone with sufficient experience in flying Airbus products knows this.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#184

Post by VBprogrammer »

blackflame7000 wrote: post #33
ceejayoz wrote: post #23

Earlier quoted context omitted.

Aircraft don't have to have flaws to crash, unless you count the human pilots, air traffic controllers, maintenance crews etc. as flaws. You could have a perfect aircraft with no flaws, and a human could still manage to crash it. See the Germanwings flight for a good example.

The flaw was allowing a single pilot in the cockpit and allowing the co-pilot to get locked out. But yes I do agree that in theory its possible to have a perfect aircraft and still crash due to some act of God. Nevertheless the context was with respect to making an aircraft with known flaws safer

You could hardly describe that as a flaw when the alternative was 9/11. It's a trade off on balance of probabilities. A suicidal copilot can still to this day crash any aircraft with only slightly more creativity. For example hitting the fuel cutoffs at 500ft after takeoff.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#185

Post by VBprogrammer »

tropo wrote: post #118
lutorm wrote: post #106

Earlier quoted context omitted.

True, there are planes that compress the struts before retracting the gear for the gear to fit, so perhaps something like this could be designed for the 737 too? But that's increased complexity on a non-redundant part that you definitely don't want to fail, so it's not obvious how the trade comes out...

Not "perhaps". It actually was designed for the 737 MAX, which comes in 4 lengths. Only the long one gets the fancy gear. Short video with gear model in action: https://www.youtube.com/watch?v=F4IGl4OizM4 https://www.geekwire.com/2018/boeing-737-max-10-landing-gear... Scroll down for a nice diagram: http://www.b737.org.uk/737max10.htm

To be fair a similar system on the Dash 8 Q400 has a pretty nasty habit of folding up on landing.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#186

Post by pbhjpbhj »

afthonos wrote: post #170
mikekchar wrote: post #160

Earlier quoted context omitted.

Yeah, this is something that I think doesn't really resonate with people well. The reactor site is 25 meters above sea level. I'm not exactly sure how high the generators were, but they were well above the level that experts thought was safe at the time. The earthquake was a 1 in 1000 year event and so there was no data on record to help them model the resultant tsunami. In the years following the tsunami, the way pe…

Agreed. I think the background you shared shows one of the big problems in design: it's always easy to see the tsunami markers after the fact and say "the information was there all along". It's a lot harder to pick them out from a thousand information sources that are, a priori , just as compelling. Looking for those markers before design would have required looking at every bit of evidence at least as compelling as…

FWIW dreamcompiler said "simply siting the generators above ground".

That doesn't mean it's easy to realise the need to do that action, it means it's not a _complex_ action in itself.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#187

Post by simion314 »

shaki-dora wrote: post #154
Aeolun wrote: post #88

Earlier quoted context omitted.

> The root problem is the culture at Boeing and the FAA has shifted from safety first to profit first. So the same problem that pervades society everywhere now? I’m not sure if that wasn’t the case before, but it feels to me that people previously wanted to make lots of money by building great products, and they’ve just left the ‘building great products’ part behind.

Despite the 737 Max fiasco, airplanes today are far safer than ever before. Since 1970, annual deaths have been cut by >80%, while air traffic has increased by a factor of 10. Cars have seen similar improvements. So have food hygiene, workplace safety, and most any measurable safety record I can think of.

You are using statistics wrong here, FAA process changed , Boeing entered a panic mode so their process changed too, applying statistics from the past where processes were different(FAA did its job and Boeing was no cutting corners) is incorrect.

We need new statistics, and this are the stats for the recent Boeing plane where the MAX crashed 2 times, first crash was blamed on the pilots and no serious urgent investigation was performed, the MCAS issues that were discovered were trivialized, still Beoing is trying to shift t6he blame on a bad software and not on the actual causes .

My point is that you can't use statistics that way, there are rules on how to apply them correctly and many pitfalls when applying statistics in real world scenarios.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#188

Post by wnkrshm »

kunday wrote: post #167
bjourne wrote: post #133

Since this thread is already full of armchair airplane engineers opinions about the root cause, I'll add mine too: Never ever write new software under the condition that it must work EXACTLY as old software. It can't be done and you'll always miss something. Case in point: Wine. They've been at it for years and the emulation layer is still far from perfect. It works 99% of the time which is good enough for games, but…

Fair point. Compaq in 1980's is probably the best case for reverse engineering and building a robust system. In some cases it out performed IBM PC's. However, I have to admit, reverse engineering a home desktop is different from a airline software, considering that bugs can instantly kill people.

Also, if you rebuild a system in isolation, you have to reproduce all the bugs - since you do not know which of the bugs are load-bearing, i.e. other systems have been engineered to depend on the bugs, whether by accident or intentionally.

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#189

Post by BorRagnarok »

jussij wrote: post #41

The FAA suffered a major loss of credibility in their handling of the first round of testing/accreditation of the MAX. The FAA can't afford another stuff up this second time around and as such I suspect they will be checking every aspect of the plane in very fine detail. That could spell more trouble for Boeing.

I still don't trust the FAA at all. They've been sourcing out their own work to Boeing since the 787 Dreamliner [0]. That's seven years ago. I don't think this will make them change their practices. The 787 fiasco certainly didn't.

Personally I'd be happiest if the world just scrapped all the Max-es. Just scrap 'em, let Boeing go out of business, it's what they deserve now, they shouldn't exist anymore as a company. There are enough businesses that happily create planes without putting profit before people.

It's really too bad that there's no footage of either of the crashes, because if people could see what happened they would never fly one of those things again. That's why people don't fly zeppelins anymore. Not because of what people said or read, but because they saw. The Max deserves the same.

Do you want to fly in a plane which was created using the deaths of over 300 people to finalize the design?

[0] The Boeing 787: Broken Dreams, Al Jazeera Investigations, https://www.youtube.com/watch?v=rvkEpstd9os

Re: FAA Finds New Risk on 737 Max, Orders Boeing to Make Changes

#190

Post by tluyben2 »

Aeolun wrote: post #88
iClaudiusX wrote: post #78

Earlier quoted context omitted.

The root problem is the culture at Boeing and the FAA has shifted from safety first to profit first. The investigative reporting from The Seattle Times[0] indicates that safety engineers were pressured to avoid delays to rush out a competitor to the A320. Furthermore, their safety analysis was based on flawed assumptions to meet an artificial constraint of not requiring pilot simulator training in order to appease th…

> The root problem is the culture at Boeing and the FAA has shifted from safety first to profit first. So the same problem that pervades society everywhere now? I’m not sure if that wasn’t the case before, but it feels to me that people previously wanted to make lots of money by building great products, and they’ve just left the ‘building great products’ part behind.

There are still companies that do that; the ones I'm aware off are mostly from Germany and Japan. Like assembly line robots, but also Panasonic (and maybe Fujitsu; haven't tried them for a while, but I used to be a big fan of their 2-in-1's P1510 rang) laptops (especially the Japan-only ones). They would not sell anywhere else because they are crazy priced, but they are virtually indestructible and go on forever.
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