281–290 of 365 posts
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re go down to 3: Use different words and see if you think it was reasonable roughly 10x going down to 3x would also mean it would go up to 17x. That's a pretty wide range, so I don't think that order of magnitude is going to ever really be similar to 3x of something on the basis of what it means.
but what about a rough order of magnitude? There is definitely some qualifiers you can put on "order of magnitude" to make it include 3.
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The article is a bit ambiguous to me about whether it was 40 minutes after landing or 40 minutes after they failed to restart the engines. The former is sensible to me since it'd take time for them to try to restart the engines and make sure the plane is otherwise safe (probably some kind of checklist to do as well). Some other articles on this explicitly say it was 40 minutes after landing.
I wouldn't call it ambiguous: > The pilots followed their checklists and worked with maintenance personnel via phone to troubleshoot, but were unable to get the engines to relight. This left the aircraft stranded and led to the closure of the runway. A tow truck arrived some 40 minutes later to tow the aircraft off the runway.
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It's worse when they are right though. I wish I could say that had not happened to me.
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.
(Somewhat frighteningly, two of those people are doing that at Facebook right now...)
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physics says no. There was something wrong with that demo if this was the conclusion.
Feynman says yes, except at very low speeds. https://en.wikipedia.org/wiki/Feynman_sprinkler
Here's my caveman f=ma thought experiment:
1. make it 2-d.
2. replace the fan with a person sitting on a chair on a frictionless surface.
3. instead of air it's an endless field cinder blocks ahead of him.
the person reaches out, and pulls in a cinder block. f=ma says they each move toward the other while the center of mass of the combination of them does not move.
Now, if he throws the cinderblock behind him, he moves further forward - this would be analogous to an airplane propeller. or a fan in an open pipe.
If he, um, splits the cinderblock in two and places each half directly off to his sides there is no net force exerted on him by this. This is the fan in a T-shaped pipe.
the fan+pipe grabs air from ahead, moves this mass backward and then sets it aside. it's not a jet-engine, but it is moving the air mass toward itself and must be moved equally and oppositely.
I don't think it's essential to worry about how the air/blocks rearrange themselves after this - but if the blocks surround and jostle, that's just another effect layered in super-position over this one, and if we don't agree so far then it will only make things more confusing
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Yes, Boeing still puts the RAT - ram-air turbine - electrical backup system on their planes.
Why "still"? Even if the chances of a failure of both engines is almost zero, it has happened that there are losses of fuel. The ram-air turbine allows the pilots to have some instrumentation. That's super useful, for example in this accident: https://en.wikipedia.org/wiki/Air_Transat_Flight_236
Ideally, yes. I submitted a recent incident where the RAT deployed on a 777 because it's so unusual (and was also not due to lack of fuel):
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> That aircraft was knowingly flown with multiple broken sensors. It was unsafe on takeoff. You'll need to cite that, since it contrary to any information I can find on the Lion Air accident e.g.: > The chief executive officer of Lion Air, Edward Sirait, said the aircraft had a "technical issue" on Sunday night, but this had been addressed in accordance with maintenance manuals issued by the manufacturer. Engineers h…
From the same Wikipedia article that was just linked: > "The aircraft suffered an airspeed indicator problem for its last four flights, including the flight to Denpasar. Thinking that it would fix the problem, the engineers in Bali then replaced one of the aircraft's AoA sensors, but the problem persisted on the penultimate flight [...] [the crew] recorded a twenty-degree difference between the readings of the left A…
More important though is that the 737 MAX differs wildly from earlier 737s in how much it relies on the AoA data. Mechanics and pilots not experienced with the MAX were probably operating under the (false) assumption that a bad alpha vane wouldn't be the end of the world. In fact displays indicating the angle of attack and warnings about disparity between the alpha vanes is an optional feature on the 737. It's considered that unimportant.
The key differences from earlier 737s are that the MAX uses the AoA data to calculate airspeed and that the MAX may use a single AoA input to try to kill you. I believe the former was disclosed, but considered how short the differences training is may have been easily overlooked. The latter, of course, was not disclosed until the crash.
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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?
Non-suicide doors[1] in cars are very difficult to open at 60 mph. Between air pressure, and poor leverage, you are going to have a hell of a time doing it. [1] https://en.wikipedia.org/wiki/Suicide_door
This is really strange. Not only did they have a dual engine failure, they couldn't restart while stuck on the runway. After 40 minutes, the aircraft had to be towed in. Then maintenance couldn't find a fault. This is an ANA aircraft, which means it's probably maintained well and flown by competent pilots. Looking forward to a good analysis on this. Most large aircraft have a "weight on wheels" switch, activated when…
I really do find the inability to restart extremely interesting though. I'd bet it's a bug somewhere, but it would be alarming if Boeing programmed in a lock-out on the failed engine(s) (I've heard it talked about as a solution to the sudden deployment of reverse thrust in flight) .
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It probably takes 15 minutes to drive there, 10 minutes to hook up the plane and 15 minutes to drag it back. Seems to make sense to me.
It doesn't say "40 minutes to be towed back" it says "A tow truck arrived some 40 minutes later to tow the aircraft off the runway." 40 minutes for the truck to arrive ?