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Author Topic: lasers blinding pilots
Ashitaka

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Icon 1 posted October 25, 2010 12:27      Profile for Ashitaka     Send New Private Message       Edit/Delete Post   Reply With Quote 
I just saw anouther thing on BBC how often pilots are apparently being blionded by lasers from people shining them at the cockpit from the ground. ( links to follow when I get around to looking a few of these stories up)


Leaving aside how difficult I think it would be to hit a moving plane cockpit window from the ground 1 km away as it lands or takes off, how bright could this laser light possibly still be once it hits the retina in the cockpit.

Despite all appearances, the light of a laser does spead out athe farther it travels. So the first thing is to find out how fast the light of a laser spreads out.

Then you have to figure out what laser tehy are useing on the ground, ( probably not an industrial cutting laser) and find out how much energy these thigns give out.

While at close range the entire energy of the laser being concetrated in a circle with say r= 2mm, by the time that light reaches the plane, the same amount of energy is going to be spread out in a circle of r=x.

and then you have to assume that much of this laser light is going to be deflected by moisture and pollution in the atmosphere.

I am not saying that I don't believe a pilot cannot be blinded. I am just saying these reports seem suspect to me, mostly because these news reports lack specifics.

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Ashitaka

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Icon 1 posted October 25, 2010 12:45      Profile for Ashitaka     Send New Private Message       Edit/Delete Post   Reply With Quote 
Oh, look what I found from the FAA here.

Edit , never mind, I guess they did, but the error bars is still a good complaint.


*Look a the error bars on thier graphs, they don't have the minus error bars because it they would go well into negative numbers.

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"If they're not gonna make a distinction between Muslims and violent extremists, then why should I take the time to distinguish between decent, fearful white people and racists?"

-Assif Mandvi

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TheMoMan
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Icon 1 posted October 25, 2010 14:51      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
____ Ash, where I worked we had some Lasers, up to 50KW in the beam. They were used to weld stainless steel parts. they had a targeting laser of 100mw that we used to aim and focus the final lens. the targeting laser was red, the working one green, the circuits could not be turned on for the high power with any gaurd/shield open.

____ Now comes the question, what type of laser was hitting the plane, a construction leveling laser, a surveyers laser used over great distances, who is to say that the hit was not inadvertant?

____ I also do not think someone could target a windshield from out side the laser free zone.

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Benjamin Franklin,

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The Famous Druid

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Icon 1 posted October 25, 2010 15:41      Profile for The Famous Druid     Send New Private Message       Edit/Delete Post   Reply With Quote 
Ash, 21% of pilots in the study aborted landing when hit with the mid powered laser, 15/40 reported flashblindness, 75% reported some impairment.

That's good enough for me to advocate castration for those caught doing this incredibly stupid and dangerous thing.

As for your comment on the error bars, there's no need to read the error bars on the graph, the numbers are given in the introduction, and none go 'into the negatives' (which would be meaningless on a 1-5 scale).

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Ashitaka

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Icon 1 posted October 25, 2010 16:28      Profile for Ashitaka     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by The Famous Druid:


As for your comment on the error bars, there's no need to read the error bars on the graph, the numbers are given in the introduction, and none go 'into the negatives' (which would be meaningless on a 1-5 scale).

I just noticed the graph starts at 2 and not zero, so the error bars would not go negative, but the error bars are very important.

The results are all around three, which means moderate performance effect of the laser, but the error bars are 1.5, which means the actual results for having a laser shinned on a pilotis somewhere between almost no effect (1.5) and almost a very great effect (4.5).

An objective interpretation of the results would be that it is entirely person specific and not laser specific. They should figure out why some people are not effected by these lasers and teach those who are greatly effected how to cope.


I am in no way advocating ever to shine a laser at an airplane, I am just sceptical. It doesn't add up.

There are hundreds of reports of lasers being pointed at planes. They cannot all be terrorists tryig to down planes. It cannot be boredom. It would seem to have little effect other than a few aborted landings ( are these people trying to drive ticket prices up?)

The news reports, the effects, the results, somehting doesn't add up.

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"If they're not gonna make a distinction between Muslims and violent extremists, then why should I take the time to distinguish between decent, fearful white people and racists?"

-Assif Mandvi

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GrumpySteen

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Icon 1 posted October 25, 2010 16:47      Profile for GrumpySteen     Send New Private Message       Edit/Delete Post   Reply With Quote 
Ashitaka wrote:
It cannot be boredom.

You are seriously underestimating what happens when you combine boredom and stupidity (and sometimes alcohol).

Have you gone to a movie theater and been annoyed by some moron shining a laser pointer at the screen? I dare say most people who go to theaters regularly have and there's no reason for it other than boredom and stupidity (and sometimes alcohol).

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Xanthine

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Icon 1 posted October 25, 2010 18:12      Profile for Xanthine     Send New Private Message       Edit/Delete Post   Reply With Quote 
One in five pilots waving off is more than enough to be worrisome, especially with air travel being the bitch it is these days. Can you imagine missing a connection because some jerk-off confused the pilot with a laser? Or, worse, crashing?

Anyway, you don't need to send a pilot to the hospital with laser-burned eyes to cause the pilot a problem while they're in the air. A bad case of the blinks and some after images will do the job nicely. Not only that, but you don't need a multi-kW laser to burn someone's eyes out. You can achieve that with half a watt (the bottom cut-off for a Class IV continuous wavelength) and you can definitely make someone really uncomfortable with any subcategory of a Class III (for reference, many laser pointers and sights on weapons are Class IIIs). In fact, for the upper end of Class III (IIIb) goggles are a good idea...and some green laser pointers are IIIb.

Also, the dispersion of a laser is more a question of optics than power. Is it collimated? Is it focused? And how far from the focal point is the target? Also, for the purposes of a douchebag at an airport, the margin of "good enough" is pretty damn wide.

As for why someone would do it, well, the world is full of douchebags.

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TheMoMan
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Icon 1 posted October 26, 2010 06:53      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
____ Okay, the prospect of some one hitting the windshield of an airplane during takeoff or landing is low, these lasers do not have sights built on to the case. Setting one up to hit a target, and then adjusting a good scope to the dot of light, now it is only good at that range parallax will rear its ugly head. The companies that tile farm fields used to use laser levels but stopped because of workers getting flashed, they have all gone to high res GPS.

____ Now back to my own experiences we used to teach flight crews to find the rescue raft in the ocean. In the raft there was a signaling mirror do you know how hard it is to put the beam of light on an aircraft? Now shoot off a star pistol and they knew you were there.

____ I have been attempting to build a seismic detector, non recording just detecting. I have some very sensitive photo cells, from garage door openers the safety switches so the door does not crush your kids. Now I have mounted the sender on one beam in the barn, and am trying to reflect the beam back to the receiver right next to the sender. I do not know how the installers get them aimed during an install because they work good at less than four feet, but go over seven and they are blind.

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Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.


Benjamin Franklin,

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GrumpySteen

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Icon 1 posted October 26, 2010 16:50      Profile for GrumpySteen     Send New Private Message       Edit/Delete Post   Reply With Quote 

Stupidity and boredom (and probably alcohol)


19-year-old Nathan Ramon Wells last year saw a California police helicopter and decided to aim a laser pointer at it, causing the pilot to suddenly change course during a burglary investigation. Now he's going to federal prison for 15 months.

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TheMoMan
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Icon 1 posted October 26, 2010 17:57      Profile for TheMoMan         Edit/Delete Post   Reply With Quote 
____ As they say on Blue Collar Comedy, "Heres your sign"

____ I still say that hitting the windshield of a jet liner during landing would be hard to do. You would have to watch from a good vantage for long enough to have a feel for how certain planes land, before giving away what you are up to. Then what if you got the wrong side and not the active pilot.

____ The writer of that article thought the punishment too harsh, let me tell you small arms fire is no picnic while you're in a Rescue (Dusty) Chopper.

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Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.


Benjamin Franklin,

Posts: 5848 | From: Just South of the Huron National Forest, in the water shed of the Rifle River | Registered: Sep 2002  |  IP: Logged
The Famous Druid

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Icon 1 posted October 26, 2010 18:55      Profile for The Famous Druid     Send New Private Message       Edit/Delete Post   Reply With Quote 
quote:
Originally posted by TheMoMan:
I still say that hitting the windshield of a jet liner during landing would be hard to do.

Tape the laser to the side of a pair of binoculars. If you get it lined up right, anything you look at through the binoculars will have a little laser dot on it.

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If you watch 'The History Of NASA' backwards, it's about a space agency that has no manned spaceflight capability, then does low-orbit flights, then lands on the Moon.

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