201–210 of 365 posts
I think the auto shutdown of engines in flight, in case it senses reverse thrust, is a great design. The 787 is a replacement for my 767 (currently a pilot on the aircraft) and in 1991 a Lauda Air 767 suffered a failure in one of its thrust reverser and it became activated during cruise. The aircraft was destroyed in flight. The thrust reversers should not activate during flight (a air/ground sensors prevents that) b…
I think the auto shutdown of engines in flight, in case it senses reverse thrust, is a great design. The 787 is a replacement for my 767 (currently a pilot on the aircraft) and in 1991 a Lauda Air 767 suffered a failure in one of its thrust reverser and it became activated during cruise. The aircraft was destroyed in flight. The thrust reversers should not activate during flight (a air/ground sensors prevents that) b…
The Boeing 787 is now about nine years old. I wonder how much of this is operator proficiency triggering latent bugs (aka, "pilots got too good at pushing buttons quickly"). The bugs in the Therac 25 were only discovered after the machine had been in production for a while (you had to be typing "too quickly" in order to get the software to trigger the bug with the safety interlock).
Make me think about could we use a robot to fuzz physical inputs.
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Is that from other experts with a very close understanding of the specifics, or random people online? What I find is you start with several viable approaches, pick one and go down the path enough to figure out the downsides. At which point you need to decide to backtrack or keep going. That’s the hard part not simply coming up with a seemingly simple solution.
> Is that from other experts with a very close understanding of the specifics, or random people online? These groups are not mutually exclusive, membership can only be assigned by a domain expert and is finally irrelevant if the other is right.
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Do you have experience with aircraft engine design, or landing protocols, or insight in to the meetings when the engines were designed? If so, I'll take back my words but considering the manufacturer doesn't know exactly why this happened, and the engineers on the ground said it seems like a "software bug", it seems a bit presumptuous and frankly a bit comical to start saying things like: "Surely a better solution wo…
I always love it when you have worked on something for months and someone new comes by and says "Why don't you just X?".
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This is an issue carmakers have had to deal with, too, since the invention of the automatic transmission: what if you put it in reverse while driving on the highway? There are a number of YouTube videos with people who have tried it. The answer, in a modern car: pretty much nothing. It just stays in Drive. On one car, it turned on the backup camera display!
Standard transmissions nowadays often include mechanical features as well that make it very difficult / impossible to engage reverse (and first gear) while going forwards at more than a few km/h.
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Make me think about could we use a robot to fuzz physical inputs.
Probably not cost effective as opposed to either making the software more resilient or just letting some monkeys/interns loose in the cockpit and pressing everything (With some focused searches obviously)
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The cruising airspeed of an airplane is faster than its landing speed. I don't know if that alone is enough to rip the engine off the wing, but it's something that it sounds like you did not consider in making your point. [EDIT remove "roughly speaking an order of magnitude"]
>The cruising airspeed of an airplane is roughly speaking an order of magnitude faster than its landing speed. No. No it is not. 787 approach speed is 145-153 knots. It does not cruise at 1400+ knots.
What would you like to call the factor? 3? Call me a weasel, but I was hoping "roughly speaking an order of magnitude" would go down to 3. I suspected it was comfortably above 2. Am I right about that?
The Boeing 787 is now about nine years old. I wonder how much of this is operator proficiency triggering latent bugs (aka, "pilots got too good at pushing buttons quickly"). The bugs in the Therac 25 were only discovered after the machine had been in production for a while (you had to be typing "too quickly" in order to get the software to trigger the bug with the safety interlock).
It's not very typical for pilots to push buttons quickly. Especially not the thrustreversers and engine and flight controls. But it is entirely possible that nobody pulled the reversers while still airborne in 9 years, because it's a very strange thing to do. A bit like opening your car door while still driving 60 mph... Nobody does that in normal operation.
You don't open and shut a door when you notice it didn't fully close because you can hear the wind?
"Boeing said that selecting full reverse too quickly upon landing before the aircraft has fully transitioned to ground mode could cause the system to activate." That sounds like apple's "you are holding it wrong" when "antenagate" happened. Not something I want to hear from an aircraft company where people's lives depend on it working.