There are no safety features that avoid flying into terrain. Warnings, yes, ("Terrain... terrain... Pull up! Pull up! Pull up!") but the plane won't avoid terrain automatically. Not even on autopilot.
And even if such a feature existed, there would always have to be some way of turning it off. Can't have some computer bug prevent pilots from landing the plane (which would be much more likely than them intentionally flying into terrain). I've actually had GPWS warnings during landing because of a database problem. It kept yelling "pull up" even after touchdown until we slowed down to taxi speed. Imagine the plane refusing to land in such case...
Fast forward a few years. Cabin attendant takes the crash axe from behind the copilot's seat and kills him with it. (One of the fire extinguishers will do fine to knock him out, too).
Really, there's only so much you can do to prevent this kind of thing. Once flying personnel can't be trusted anymore, all bets are off.
If the attacker really started killing off passengers one by one, I know what I would do: make an announcement for everyone to immediately fasten their seatbelts, and then do some very agressive manoeuvers to throw the hijackers onto the ceiling and back onto the floor a few times in succession. I may injure some passengers and cause some damage in the cabin, but it's better than seeing them get killed. The plane can do -1g and +2.5g.
Also, they need some way of recording flight data outside of the aircraft. Ideally, some kind of network between all airplanes regardelss of company, constantly exchanging information and recording each others flight data (encrypted, of course). When an airplane crashes or disappears, there's almost always multiple other aircraft within radio reception distance even in the most remote corners of the planet. The investigators could then get the flight data from those other planes' recorders.
The beeping sound (bip bip bip bip bip...) when somebody requests access to the cockpit is quite loud, you can often hear it in the background when pilots are talking on the radio. And of course when it stops, you know someone hit the switch to either lock or unlock it the door. But yes, indeed, even much fainter sounds have been used in previous accident investigations and it's quite amazing how much information they can sometimes pick up from that.
I'm not sure what the exact result of 15 degrees of downward pitch would be, but I'm pretty sure it would be a rapid but controlled descent—exactly what the telemetry shows.
It would probably have been a bit steeper than the 3000 feet per minute that were recorded. With continous forward pressure on the sidestick, the plane will indeed pitch down to maximum 15 degrees until it reaches the maximum operating speed (VMO). Then, even if you keep pushing the stick forward, it will pitch up to maintain a speed slightly above VMO. But this would probably be between 4000 and 6000 feet per minute or so, depending on weight.
It's more likely he just dialed in a low flight level and pulled the button for "open descent" to let the autopilot do it.
Regarding overriding the autopilot system, not it is not - you do not "remove" the autopilot from "normal law", as that is the normal operating law and you cannot intentionally degrade to alternate law.
Yes you can. Just push a few buttons to disable certain flight control computers, and the system goes into alternate or even direct law. I've done barrel rolls in the simulator.
I once tried to set a password for iCloud using 20 letters, numbers and punctuation marks. It was rejected because it didn't contain a capital letter. Sigh...
Result: iCloud passwords have lower entropy because the cracking algorithms no longer have to try passwords with only lower case letters. They can go through all the passwords with a leading capital letter in the same amount of time instead. (which is the obvious alteration 95% of users will make anyway)
I'm also hoping this whole thing "that, when unobserved, the photons exist in all possible states simultaneously" eventually goes away. It has to be that we can't know what state it's in, not that it's actually in all of them. Can't it? Please? At some point, this quantum stuff should stop being magic.
To quote Richard Feynman:
I hope you’ll come along with me and you’ll have to accept it because this is the way nature works. If you want to know the way nature works, we looked at it, carefully, look at it and see... that’s the way it looks. You don’t like it? Go somewhere else!
To another universe! Where the rules are simpler, philosophically more pleasing, more psychologically easy. I can’t help it, OK! If I’m going to tell you honestly what the world looks like to the human beings who have struggled as hard as they can to understand it, I can only tell you what it looks like and I cannot make it any simpler, I’m not going to do this, I’m not going to simplify it, and I’m not going to fake it. I’m not going to tell you it’s something like a ball bearing on a spring, it isn’t. So I’m going to tell you what it really is like, and if you don’t like it, that’s too bad.
(From his famous QED lectures in which he does a remarkable job of explaining quantum mechanics to ordinary people in a way anyone can understand, it's without doubt the best primer you can possibly get, and full of humor to boot.)
I never understood quantum mechanics until I saw this video. Now it sort of makes sense. Of course much of it remains pretty mysterious, but the whole particle/wave duality thing? He explains it perfectly.
Feynman had an amazing gift for explaining hard scientific concepts to ordinary people without requiring maths.
I absolutely love my limiter. Not to limit myself to speed restrictions (which I don't really... errr... respect), but as a safer alternative to cruise control. Just keep your foot on the pedal and the car will keep the set speed just like when it's on cruise control. However, when there's traffic ahead, all you have to do is lift your foot to decelerate. Then, when the road is clear again, push the pedal back down and the car smoothly accelerates back to cruising speed at whatever rate you choose. If you do need to go faster, there's always the override switch under the gas pedal if you push it in hard all the way.
On classic cruise control, you're either constantly toggling the speed up and down with the lever, or switching it off and then back on again. The limiter is much more natural, no need to touch any switches or levers. As long as the road is clear, you just keep your foot resting on the accelerator which is not fatiguing since you don't have to modulate it. I can drive hundreds of km without having to touch any levers or switches, just lifting my foot every now and then.
More importantly I have found that, when using classic cruise control, you often tend to leave it on even though there are subtle reasons for slowing down. The psychological threshold for actually turning the system off or using the brakes is too high, so you often tend to keep going at the set speed rather than slowing down a little when other cars are doing something funny. On the limiter, I often find I have already instinctively lifted my foot without even realising it.
Cruise control is really the wrong way around. The car keeps a minimum speed, allowing you to go faster but not slower unless you turn it off?! I much prefer the other way around, a car that slows down if you let go of everything and won't go faster unless you override it. In Belgium, we even have signs telling people to turn off cruise control, for example when approaching road works, for precisely that reason.
Yet another advantage of the limiter is when traffic ahead of you slows down and then very gradually accelerates again to higher speeds than you intended to drive. With cruise control, you usually turn it off for traffic and then sort of blindly go with the flow on a mental autopilot. This way you may end up speeding more than you intended. The limiter will just let the car ahead pull away from you as soon as you reach your normal cruising speed, since you never had to turn off the limiter.
By the way, speed limiters, speed limit databases and speed sign recognition is hardly a new thing, many brands already have it. It may be new for Ford, but not for other brands. Some even allow you to set a certain margin above the limit, allowing you to go faster but not too much.
I think it's interesting to see how people love this sort of thing when James Bond is doing it, yet create massive uproar when it actually happens in real life.
They are not moving through space IF we define space in one particular way. If we define it in a different way (by using different coordinates), they do move through space. Space itself doesn't really mean anything, there's nothing physical to it, it's just a big vacuum.
Frequency is certainly affected by time dilation. If an object moves away from us at high speed (not due to the expansion of space, but simply passing by very quickly), the total redshift is a combination of classic redshift and time dilation. Time dilation slows down time for the object, so that it emits light of lower frequencies (photons with a lower energy). It's called the relativistic doppler effect. The same occurs for redshift due to the expansion of space if we use a reference frame that obeys special relativity. In cosmological coordinates, you get exactly the same value for redshift but caused solely by classic redshift (with those coordinates, there's no time dilation but the speed is higher, resulting in the same redshift).
All depends on your choice of coordinates. I described two different systems:
1. A reference system that obeys special relativity. In this reference frame, nothing moves faster than the speed of light, not even those distant galaxies you are talking about. However, very distant objects are aging more slowly due to time dilation, and are compressed due to lorentz contraction. Even though the local aliens don't see anything wrong, in our reference frame they look like flat pancakes. This makes it a very subjective view of the universe, and not very practical, but perfectly in line with relativity.
2. A reference system that deliberately does not obey special relativity, but is instead chosen in such a way that the universe looks roughly the same everywhere (no lorentz contraction or time dilation from the speed of expansion). This is kind of cheating but very practical. In this reference system (which is the one most commonly used in cosmology), galaxies are indeed moving away at more than twice the speed of light, they are aging at the same rate as us, and their shape is "normal".
These two are not contradictory: we just stick different labels on the same stuff. Speed is just a change in space coordinates divided by a change in time coordinate, so by choosing different coordinates we can change the value of the speed. So yes, we do "see" galaxies moving away at 2x the speed of light if we choose to use cosmological coordinates. With special-relativistic coordinates, we "see" the galaxy moving away at a speed less than c with extra redshift because of time dilation due to its speed. The actual value for the total redshift is exactly the same. No one explanation is "better" than the other, they are perfectly equivalent descriptions using different labeling.
Master's degree in maths and just interested in physics. My explanation is probably not 100% accurate because it disregards things like gravity, but the general idea is correct as far as I know. It's certainly a lot more accurate than most popular explanations.
Not our locale. The locale over there. In the post I linked to, I explained that you could use two different coordinate systems.
1. Obeying special relativity: speed of light is the same everywhere, c relative to us, and nothing can move faster. However, distant objects that are flying away at high speed (close to c) are lorentz-contracted and time is moving more slowly for them, so the universe "looks" kind of weird at a distance. 2. Modified coordinates so that the universe looks more or less the same everywhere. In this case, the speed of light in some different area is equal to c relative to the expansion speed of that area, which may be higher than c relative to us.
Some time last year I wrote a lengthy explanation of what exactly "space itself" means. It's not really a physical thing, but rather a result of a particular choice of coordinates which turns out to be very practical.
"Speed" is just distance divided by time. Both distance and time are defined by agreeing on a particular set of coordinates. In our immediate neighborhood there isn't much discussion about what we mean, apart from which unit to use (miles, km,...) but on intergalactic distances in an expanding universe there are several different, perfectly valid choices of coordinates that yield wildly different results for distance, speed, simultaneity, etc... You can choose a coordinate system that obeys special relativity and find that nothing goes faster than the speed of light relative to us. But with different coordinates, the speed of light itself is not tied to our location but rather to local "space". That's just a mathematical convention because it turns out to be more convenient that way. Anyway, I explained it all in detail in the above link.
Apparently the goal of the European Systemic Risk Board is to safeguard financial stability in Europe. I have no idea how the CEO of a US video game company came to be the chair of that board, so I can sort of understand people asking questions. On the other hand, I don't really see the conflict of interest either, it just seems to be a weird choice.
Oh, wait a minute... maybe they meant the eSRB, the Pakistani Taxpayer Facilitation Portal?
Slashdot Mirror
There are no safety features that avoid flying into terrain. Warnings, yes, ("Terrain... terrain... Pull up! Pull up! Pull up!") but the plane won't avoid terrain automatically. Not even on autopilot.
And even if such a feature existed, there would always have to be some way of turning it off. Can't have some computer bug prevent pilots from landing the plane (which would be much more likely than them intentionally flying into terrain). I've actually had GPWS warnings during landing because of a database problem. It kept yelling "pull up" even after touchdown until we slowed down to taxi speed. Imagine the plane refusing to land in such case...
Fast forward a few years. Cabin attendant takes the crash axe from behind the copilot's seat and kills him with it. (One of the fire extinguishers will do fine to knock him out, too).
Really, there's only so much you can do to prevent this kind of thing. Once flying personnel can't be trusted anymore, all bets are off.
If the attacker really started killing off passengers one by one, I know what I would do: make an announcement for everyone to immediately fasten their seatbelts, and then do some very agressive manoeuvers to throw the hijackers onto the ceiling and back onto the floor a few times in succession. I may injure some passengers and cause some damage in the cabin, but it's better than seeing them get killed. The plane can do -1g and +2.5g.
Also, they need some way of recording flight data outside of the aircraft. Ideally, some kind of network between all airplanes regardelss of company, constantly exchanging information and recording each others flight data (encrypted, of course). When an airplane crashes or disappears, there's almost always multiple other aircraft within radio reception distance even in the most remote corners of the planet. The investigators could then get the flight data from those other planes' recorders.
The beeping sound (bip bip bip bip bip...) when somebody requests access to the cockpit is quite loud, you can often hear it in the background when pilots are talking on the radio. And of course when it stops, you know someone hit the switch to either lock or unlock it the door. But yes, indeed, even much fainter sounds have been used in previous accident investigations and it's quite amazing how much information they can sometimes pick up from that.
I'm not sure what the exact result of 15 degrees of downward pitch would be, but I'm pretty sure it would be a rapid but controlled descent—exactly what the telemetry shows.
It would probably have been a bit steeper than the 3000 feet per minute that were recorded. With continous forward pressure on the sidestick, the plane will indeed pitch down to maximum 15 degrees until it reaches the maximum operating speed (VMO). Then, even if you keep pushing the stick forward, it will pitch up to maintain a speed slightly above VMO. But this would probably be between 4000 and 6000 feet per minute or so, depending on weight.
It's more likely he just dialed in a low flight level and pulled the button for "open descent" to let the autopilot do it.
Regarding overriding the autopilot system, not it is not - you do not "remove" the autopilot from "normal law", as that is the normal operating law and you cannot intentionally degrade to alternate law.
Yes you can. Just push a few buttons to disable certain flight control computers, and the system goes into alternate or even direct law. I've done barrel rolls in the simulator.
If it includes the dashes, it's probably not even a bad one!
I once tried to set a password for iCloud using 20 letters, numbers and punctuation marks. It was rejected because it didn't contain a capital letter. Sigh...
Result: iCloud passwords have lower entropy because the cracking algorithms no longer have to try passwords with only lower case letters. They can go through all the passwords with a leading capital letter in the same amount of time instead. (which is the obvious alteration 95% of users will make anyway)
I'm also hoping this whole thing "that, when unobserved, the photons exist in all possible states simultaneously" eventually goes away. It has to be that we can't know what state it's in, not that it's actually in all of them. Can't it? Please? At some point, this quantum stuff should stop being magic.
To quote Richard Feynman:
I hope you’ll come along with me and you’ll have to accept it because this is the way nature works. If you want to know the way nature works, we looked at it, carefully, look at it and see... that’s the way it looks. You don’t like it? Go somewhere else!
To another universe! Where the rules are simpler, philosophically more pleasing, more psychologically easy. I can’t help it, OK! If I’m going to tell you honestly what the world looks like to the human beings who have struggled as hard as they can to understand it, I can only tell you what it looks like and I cannot make it any simpler, I’m not going to do this, I’m not going to simplify it, and I’m not going to fake it. I’m not going to tell you it’s something like a ball bearing on a spring, it isn’t. So I’m going to tell you what it really is like, and if you don’t like it, that’s too bad.
(From his famous QED lectures in which he does a remarkable job of explaining quantum mechanics to ordinary people in a way anyone can understand, it's without doubt the best primer you can possibly get, and full of humor to boot.)
Here's the youtube video:
https://www.youtube.com/watch?...
I never understood quantum mechanics until I saw this video. Now it sort of makes sense. Of course much of it remains pretty mysterious, but the whole particle/wave duality thing? He explains it perfectly.
Feynman had an amazing gift for explaining hard scientific concepts to ordinary people without requiring maths.
I absolutely love my limiter. Not to limit myself to speed restrictions (which I don't really... errr... respect), but as a safer alternative to cruise control. Just keep your foot on the pedal and the car will keep the set speed just like when it's on cruise control. However, when there's traffic ahead, all you have to do is lift your foot to decelerate. Then, when the road is clear again, push the pedal back down and the car smoothly accelerates back to cruising speed at whatever rate you choose. If you do need to go faster, there's always the override switch under the gas pedal if you push it in hard all the way.
On classic cruise control, you're either constantly toggling the speed up and down with the lever, or switching it off and then back on again. The limiter is much more natural, no need to touch any switches or levers. As long as the road is clear, you just keep your foot resting on the accelerator which is not fatiguing since you don't have to modulate it. I can drive hundreds of km without having to touch any levers or switches, just lifting my foot every now and then.
More importantly I have found that, when using classic cruise control, you often tend to leave it on even though there are subtle reasons for slowing down. The psychological threshold for actually turning the system off or using the brakes is too high, so you often tend to keep going at the set speed rather than slowing down a little when other cars are doing something funny. On the limiter, I often find I have already instinctively lifted my foot without even realising it.
Cruise control is really the wrong way around. The car keeps a minimum speed, allowing you to go faster but not slower unless you turn it off?! I much prefer the other way around, a car that slows down if you let go of everything and won't go faster unless you override it. In Belgium, we even have signs telling people to turn off cruise control, for example when approaching road works, for precisely that reason.
Yet another advantage of the limiter is when traffic ahead of you slows down and then very gradually accelerates again to higher speeds than you intended to drive. With cruise control, you usually turn it off for traffic and then sort of blindly go with the flow on a mental autopilot. This way you may end up speeding more than you intended. The limiter will just let the car ahead pull away from you as soon as you reach your normal cruising speed, since you never had to turn off the limiter.
By the way, speed limiters, speed limit databases and speed sign recognition is hardly a new thing, many brands already have it. It may be new for Ford, but not for other brands. Some even allow you to set a certain margin above the limit, allowing you to go faster but not too much.
I know, I hate it when people do what I did there...
I think I may have mistaken the second line for a signature and therefore skipped it. (I know, the actual sig was below the "--")
I think it's interesting to see how people love this sort of thing when James Bond is doing it, yet create massive uproar when it actually happens in real life.
Oops, I didn't see the "pretend it's the 1980s" part. Woosh indeed.
It's actually odd plates on odd days, even plates on even days.
Petrol in Europe is supposed to be lead free.
The rule does not apply to "clean" cars (electric, hybrid,...). Never mind some hybrids burn more fuel than non-hybrids...
They are not moving through space IF we define space in one particular way. If we define it in a different way (by using different coordinates), they do move through space. Space itself doesn't really mean anything, there's nothing physical to it, it's just a big vacuum.
Frequency is certainly affected by time dilation. If an object moves away from us at high speed (not due to the expansion of space, but simply passing by very quickly), the total redshift is a combination of classic redshift and time dilation. Time dilation slows down time for the object, so that it emits light of lower frequencies (photons with a lower energy). It's called the relativistic doppler effect. The same occurs for redshift due to the expansion of space if we use a reference frame that obeys special relativity. In cosmological coordinates, you get exactly the same value for redshift but caused solely by classic redshift (with those coordinates, there's no time dilation but the speed is higher, resulting in the same redshift).
All depends on your choice of coordinates. I described two different systems:
1. A reference system that obeys special relativity. In this reference frame, nothing moves faster than the speed of light, not even those distant galaxies you are talking about. However, very distant objects are aging more slowly due to time dilation, and are compressed due to lorentz contraction. Even though the local aliens don't see anything wrong, in our reference frame they look like flat pancakes. This makes it a very subjective view of the universe, and not very practical, but perfectly in line with relativity.
2. A reference system that deliberately does not obey special relativity, but is instead chosen in such a way that the universe looks roughly the same everywhere (no lorentz contraction or time dilation from the speed of expansion). This is kind of cheating but very practical. In this reference system (which is the one most commonly used in cosmology), galaxies are indeed moving away at more than twice the speed of light, they are aging at the same rate as us, and their shape is "normal".
These two are not contradictory: we just stick different labels on the same stuff. Speed is just a change in space coordinates divided by a change in time coordinate, so by choosing different coordinates we can change the value of the speed. So yes, we do "see" galaxies moving away at 2x the speed of light if we choose to use cosmological coordinates. With special-relativistic coordinates, we "see" the galaxy moving away at a speed less than c with extra redshift because of time dilation due to its speed. The actual value for the total redshift is exactly the same. No one explanation is "better" than the other, they are perfectly equivalent descriptions using different labeling.
Master's degree in maths and just interested in physics. My explanation is probably not 100% accurate because it disregards things like gravity, but the general idea is correct as far as I know. It's certainly a lot more accurate than most popular explanations.
Not our locale. The locale over there. In the post I linked to, I explained that you could use two different coordinate systems.
1. Obeying special relativity: speed of light is the same everywhere, c relative to us, and nothing can move faster. However, distant objects that are flying away at high speed (close to c) are lorentz-contracted and time is moving more slowly for them, so the universe "looks" kind of weird at a distance.
2. Modified coordinates so that the universe looks more or less the same everywhere. In this case, the speed of light in some different area is equal to c relative to the expansion speed of that area, which may be higher than c relative to us.
Really, try reading the post I linked to again.
Some time last year I wrote a lengthy explanation of what exactly "space itself" means. It's not really a physical thing, but rather a result of a particular choice of coordinates which turns out to be very practical.
http://science.slashdot.org/co...
"Speed" is just distance divided by time. Both distance and time are defined by agreeing on a particular set of coordinates. In our immediate neighborhood there isn't much discussion about what we mean, apart from which unit to use (miles, km,...) but on intergalactic distances in an expanding universe there are several different, perfectly valid choices of coordinates that yield wildly different results for distance, speed, simultaneity, etc... You can choose a coordinate system that obeys special relativity and find that nothing goes faster than the speed of light relative to us. But with different coordinates, the speed of light itself is not tied to our location but rather to local "space". That's just a mathematical convention because it turns out to be more convenient that way. Anyway, I explained it all in detail in the above link.
Apparently the goal of the European Systemic Risk Board is to safeguard financial stability in Europe. I have no idea how the CEO of a US video game company came to be the chair of that board, so I can sort of understand people asking questions. On the other hand, I don't really see the conflict of interest either, it just seems to be a weird choice.
Oh, wait a minute... maybe they meant the eSRB, the Pakistani Taxpayer Facilitation Portal?
And which will be available "soon".