#199441 - 04/01/10 04:32 PM
Re: silent crashing airplane hazard
[Re: Compugeek]
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Old Hand
Registered: 03/03/09
Posts: 745
Loc: NC
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I gotta think 100% is correct, if only for that one second, that one time only.
If a guy walked up to me today, and said - Hey, what are the odds that... fact of the situation... I would say, "well, as it has happened already - 100%", meaning that it could and did happen. Same as asking me the odds that man will walk on the moon, it happened, so 100%. But I think we are talking about two different things.
Every event has a 100% chance of happening, if the event can physically happen. However; the odds that it will happen at any one particular second in a certain place is what you are talking about. Apples and oranges.
Ask me the odds that this happens again - I don't wanna do the math and my calculator would run outta numbers.
Might happen now or in the future versus happened already.
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#199444 - 04/01/10 05:03 PM
Re: silent crashing airplane hazard
[Re: JBMat]
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Enthusiast
Registered: 08/09/09
Posts: 392
Loc: San Diego, CA
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Understood, but it just doesn't work that way.
When you flip a fair coin, the chance of a heads is 50%. Whether it comes up heads or not, the chance is still 50% that it could have come up heads. If it does come up heads, that only means the 50% chance came up. It was still only a 50/50 chance. Even if you get heads ten times in a row (a roughly 1/1000 chance), as long as it's a fair coin, and nothing else is affecting the toss, the odds for the next flip are still 50/50. And the odds against ten heads in a row are still 1024 to 1. Even after it happens.
Same thing here. Let's assign the chance of a jogger on the beach getting hit by an airplane making an emergency landing on any given day a 1 in a million chance.
So, on any given day, there's a 1/1,000,000 chance of the event. It's 1/1,000,000 the day before the event. It's 1/1,000,000 the day after the event. And even on the day it happened, the chance of it happening was still 1/1,000,000.
It's just that, on that day, it actually happened. The fact that it happened doesn't change the chance of it happening. "After the event" has no effect on the odds of the event.
So, for that day, for that particular jogger and pilot, the chance was still 1 in a million. They just got a really bad roll of the dice.
What you're talking about in the 100% is that, no matter how slim the chance, sooner or later, an event WILL happen, if you just have enough "tries". That's true. With enough attempts, no matter how unlikely, anything that's actually possible will happen sooner or later. But the odds for each individual 'attempt' are still however long they are.
Edited by Compugeek (04/01/10 05:05 PM)
_________________________
Okey-dokey. What's plan B?
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#199861 - 04/08/10 08:00 AM
Re: silent crashing airplane hazard
[Re: ireckon]
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Old Hand
Registered: 06/03/09
Posts: 982
Loc: Norway
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I'm not sure if it was mentioned, but sound is not all that fast. Sound travels about 8-10 times faster than most aircrafts landing speed, from my back-of-the-head-in-the-spur-of-the-moment calculations.
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#199874 - 04/08/10 04:36 PM
Re: silent crashing airplane hazard
[Re: MostlyHarmless]
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Pooh-Bah
Registered: 04/01/10
Posts: 1629
Loc: Northern California
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I'm not sure if it was mentioned, but sound is not all that fast. Sound travels about 8-10 times faster than most aircrafts landing speed, from my back-of-the-head-in-the-spur-of-the-moment calculations. I really meant that sound is not fast relative to the speed of light. With this idea of a whistle, you need as much advanced warning as possible. There is not one fraction of a second that can be delayed. Light (vision) would NOT be fast enough for a jogger, who doesn't have super powers, to process the information and to run completely outside of the crash zone. By the time the jogger realized the plane was coming straight toward him, the plane would be maybe 3 seconds away. At that point the jogger would have to sprint maybe 100 meters in about 3 seconds to get outside of the crash zone. Further, the jogger would have to make sure to run those 100 meters perpendicular to the line of flight to avoid the crash. Since vision (light) isn't fast enough, sound isn't fast enough. As an analogy, when watching a soccer game in a stadium, the sound of the soccer ball gets to the viewer about one second (or more) later. In the ridiculous scenario of the plane crash, the time delay would be even longer because the plane is farther away. That's extra time that the jogger could not afford to spare. Further, the crashing plane would be traveling a lot quicker than a soccer ball.
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#199878 - 04/08/10 05:21 PM
Re: silent crashing airplane hazard
[Re: ireckon]
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Old Hand
Registered: 06/03/09
Posts: 982
Loc: Norway
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The speed of sound versus speed of light is totally irrelevant to this issue and only confuses this matter. If you calculate how far away the plane is when you need to hear it then you need to correct for the speed of sound - about 10-20% or so. Otherwise, it is not important.
How many seconds do you need to realize what is happening (Gosh, I'm about to be hit by an airplane) and get out of the crash zone??? If the whistle can give you that many seconds then a whistle is good.
Take your exampe - a 100 meter dash plus reaction time. How fast can you run 100 meters if your life depends on it? Say 12 seconds, plus 3 seconds reaction time, that's 15 seconds. If the plane travels at 33 meters per second (118 km/hour, 73 miles/hour) then you need to start reacting when that plane is 495 meters away (541 yards, 1624 feet).
If you detect the plane by whistle you need to correct for the fact that the speed of sound is 330 meter per second and your plane travels at 33 meters per second. You need to add 10% to those distances: You need to hear that whistle when the plane is 544 meters away, not 495 meters.
The airplane, however, is not 100 meters across. More like 10 for a small airplane. Moving as little as 5 meters should in theory be enough to avoid being hit. Which gives you, maybe 5 seconds: 3 to react and 2 seconds to move. You need to realize something is wrong when the plane is 165 meters away. Add for the speed of sound: 182 meters, 600 feet, 200 yards.
Oblivious to the surroundings as most people are with headphones, I don't think all the whistles in the world would make any difference at all.
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#199917 - 04/09/10 12:59 PM
Re: silent crashing airplane hazard
[Re: ireckon]
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Old Hand
Registered: 06/03/09
Posts: 982
Loc: Norway
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Sorry for not writing this explicit in my previous post: I agree that reacting in time to get out of harm's way is not realistic except for those with super-human awareness. The most optimistic estimate (spotting 183 meters, 5 seconds to react and move) may be borderline possible for some.
Most people would just stare at the plane, not realizing at all that this plane will in fact kill them.
I guess I got caught in the physics of the problem, calculating the distances and all. The results should speak for themselves. Obviously they don't.
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#199918 - 04/09/10 01:09 PM
Re: silent crashing airplane hazard
[Re: MostlyHarmless]
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Old Hand
Registered: 03/03/09
Posts: 745
Loc: NC
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It was the jogger's time to go. The Powers that Be decided to make it memorable for the rest of us.
Edited by JBMat (04/09/10 01:09 PM) Edit Reason: cain't spel
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#199920 - 04/09/10 01:36 PM
Re: silent crashing airplane hazard
[Re: JBMat]
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Enthusiast
Registered: 08/09/09
Posts: 392
Loc: San Diego, CA
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All the article says is "bloodied body". So we don't know (unless I missed it re-reading the thread ) whether it hit him full on, in the upper body, or just clipped him in the head. So maybe, if he'd seen it, all he'd have had to do was thrown himself to the ground. Normal human reaction time is 1/2 to 3/4 of a second. You don't have to register "OMG, there's an airplane coming right at me, I need to run to the side and get out of the way." All you need is "OMG there's something coming right at me!" And we're all pretty good at that basic level of survival response. Ultimately, though, this was just an unfortunate concatenation of circumstances. Or "Stuff happens."
_________________________
Okey-dokey. What's plan B?
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