back to article Aussie laser-pointer dazzle attacks on airliners: Bad

Australian politicians are demanding restrictions on the ownership of laser pointers in the land down under. The banning calls follow a series of widely-reported incidents in which individuals on the ground have attempted to dazzle pilots of commercial aircraft making approaches to landing. A particularly troublesome dazzling …

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I sympathise. Landing is HARD!

If you get hit in the eye by a bright light on approach then you will be uncomfortable and/or spooked. Your concentration will be shot and you've probably missed your place in the checklists. You should do a go-around and retry the approach.

Yes, the machine could probably land itself but the human pilot is there in case it does not. One flight in thousands they'll earn their money for the year by doing so.

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Ian
Alert

@ Tom (12:07)

"When a plane lands, It has it's nose up, quite simply, from the ground you wouldn't have the required clean tradgectory,"

Unfortunately that's not true.

1) It depends on the aircraft. A B757 approaches nose low, a B747 approaches nose high. They LAND nose high, for obvious reasons, but approach is a different matter.

2) By necessity (unless you are flying a Spitfire or a P-51 Mustang, for example), the pilots have to see the runway. That is ALL of the runway, including the undershoot, so you know how you are positioned in relation to it. If you look at all ILS equipped runways, they have an array of lights on the approach to the runway which are used for visual tracking / confirming / positioning on a precision approach. These light arrays are visible by the pilots until short final approach, as the aircraft goes over them. They are also almost always outside the aircraft perimiter fence and thus usually in publicly accessable areas. There's no problem at all getting line of sight at the flight deck windows.

Ian P.

CAA PPL/IMC (although admittedly lapsed)

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Underpowered

If a laser beam indeed spreads out to a metre or so across, there's no way a 300mW laser could fill the inside of a cockpit "with blinding green light".

300mW spread over a square metre is bugger-all in terms of energy. Sunlight gives something like 1kW/square metre.

To approach sunlight intensity, you'd need a real (not just claimed) 300mW concentrated into a spot about 2cm diameter.

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Anonymous Coward

Maybe it was a surveyor's laser?

My bosses have given up the lease on our current office, and a new prospective tennant recently had the surveyors in. I was walking down the corridor and was suddenly hit in the eye by a red laser.

Whatever sort of machine it was, it scanned its laser in a little square and flickered over my right eye very rapidly, dazzling me quite badly. Cue shut eye and pointing my remaining open eye at the wall.

Stick a green laser in one of those machines and targetting a plane would be dead easy.

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@David

That would be true, where we talking polychromatic white light. Unfortunately, we're talking not just about green light here, we're talking about a laser with a single frequency somewhere in the green spectrum. This means it focuses all that energy into a relatively small part of your eye's ability to see colours, unlike sunlight which spreads it out nicely.

Try this little experiment for fun. Take a halfway decent mirror. Place it 50 meters away. Point a 50 milliwatt green or red laser at it and look at the dot.

Come back when you've regained your vision a few minutes later and post a sane reply.

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But WHY

Why do we need laser pointers that can reach a mile away? Seriously, the little one I had on my key ring years ago could reach about 30m, how big a screen do you think you're going to be pointing to?

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Anonymous Coward

Possible solutions

I am always amazed at how people are answering to some articles.

One solution to reduce problems with laser is the use of polarizer filter on the windows. That's relatively low tech and should handle most cases.

If you want to go deeper in terms of technology, you could then consider more advanced polarizer filters using LCD crystals that would be rotating with some frequency.

It won't stop the laser to go through depending on the angle, but in most case it would seriously reduce the intensity of what is going through.

Of course, the most advanced system would be a virtual reality display with multiple cameras to handle the situation. The only inherent problem with this is that you end up depending on an advanced mechanism to see what is going on. But again, it is already the case in a plane in the first place.

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Banning Lasers

Yes it’s stupid to beam lasers at aircraft or any other object where people may be dazzled. As far as I can remember there have been less than 20 reports in the New South Wales press over the last 4/5 years (the period green lasers have been readily available).

I was amused by one report recently which said the pilot reported being flashed by an “infra red laser”, I’m wondering if they have fitted civil aircraft with IR laser detectors (and anti rocket flares) lest the many terrorists who roam the world get hold of some laser guided missile!! I still have no idea how he knew he was beamed by infra red.

If the interfering politicians do ban them perhaps they can also ban the HID car headlights which temporarily blind me and many other motorists every night on the pot hole ridden roads of inner Sydney. Not that bans stop idiots anyway.

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Yes, it is a danger

I'm a pilot, an Advanced Ground School Instructor, and an FAA Aviation Safety Counselor.

Pilot work load is highest at landing. The final approach, flare, touchdown and rollout are done visually, not by instruments. On an IFR flight (most airline operations are IFR), the instruments get you to a few hundred feet short of and above the end of the runway, after that, it is entirely up to the pilot who has to look out the window.

An aircraft stabilized on final approach is on a very smooth, very predictable path. It doesn't take any great feat of marksmanship to shine a laser pointer into the cockpit, just when the pilot is looking directly out the front of the airplane, eyes intently focused in a specific direction, paying complete attention to the runway, which is going to be directly in front of him (or her).

The majority of aircraft accidents happen during the takeoff and landing phases of flight, predictably, most of them are on landing.

I suggest anyone who doesn't think this kind of crap is dangerous go for a drive on a motorcycle with their eyes shut. These morons are going to kill someone, or a lot of someones, and the longer it goes on the better chance there will be a disaster.

In the US, interfering with the duties of the flight crew is already a felony. These are the same people who throw cement blocks off overpasses onto cars below - ha ha funny funny, and people are dead.

Personally, I think the 747 ray-gun special shooting back is an excellent idea, incidentally, there is also a C-130 model ray-gun gunship which may very shortly be operational, that's another option. In the meantime, there needs to be some prompt and concentrated action in catching and punishing - severely - these clowns.

Possibly even more sinister - these are not random clowns and morons, but terrorists refining their techniques, and "the plan" is to cause a few hundred simultaneous crashes around the world - perfect use of asymmetric force, for the price of a few laser pointers off eBay, they can cause thousands of deaths, and probably get away clean.

Sleep well tonight, just because you're not paranoid doesn't mean they aren't out to get you.

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!Duh!

What's more idiotic: People doing it, or well paid IT staff disbelieving actual 'plane diversions because they 'think' it can't happen?

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Boffin

Astronomy

Amateur astronomers sometimes use green lasers as a coarse aiming device for their 'scopes, and to point out areas of interest. They're particularly good because, for a given power, green is perceived as brighter than any other colour: the human eye is most sensitive to 550nm wavelength radiation.

UK law and HSE guidance should prevent the sale of all but <1mW Class 2 lasers for general-purpose applications, including amateur astronomy. Perhaps the Australians should look to issue similar guidance before sending a volley of Hellfire missiles down on some unsuspecting stargazers.

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J
Dead Vulture

Hm...

First: word of the week goes for "tradgectory". For those who are not in possession of an up-to-date, world-class dictionary, that means: the trajectory of a tragedy-causing element.

Now, I wonder how many of these incidents have been caused by El Reg readers out there with their mates betting: I'll show you idiots it can't be done, the angle, the power, the speed, look! Oh, the landing has been aborted... Run!

And last but not least, can Mythbusters do an episode on this, pretty please? (maybe they have already, but I'm too lazy to look it up)

Vulture has looked into green laser while landing.

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Alert

A couple of minor points

My first point is that anyone sat near the end of the runway with a piece of equipment on a tripod, lining it up through a scope may well find themselves getting grabbed pretty quickly on general grounds of security.

Another point would be that the cheap, easy to find and difficult to prevent sale of source for lasers is a DVD burner; extract the laser diode, and integrate it into a standard laser pointer body and you've got a nasty bit of hardware. So banning laser pointers of any type isn't really going to work.

A DVD burner based laser point would be particularly hazardous given the combination of high output (100s of mW) and being an IR laser - there isn't any blink response to IR so you wouldn't even know you were targeted until the world went dark.

As for using it - goggles would be a must (to prevent accidentally blinding yourself), but actual targeting would be easily achieved with a standard video or digital stills camera, as this will clearly display the reflected IR.

Whether there is an actual threat to aircraft is another matter, given the range and motion of the target it wouldn't be hard to paint the target but it would be difficult to get any meaningful amount of energy through a window into someone's eyes - diffraction, absorption, scattering & movement of the target just make it too difficult. Look at the camera video from a tripod mounted laser speed camera and you'll see how hard it it to track a target, let alone a specific point on it.

So I'm not sure there's a particular problem - and if there is it can be dealt with by security/police patrols as those playing this kind of game are going to have to be in a particular location at the time, and should therefore be easily caught.

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Silver badge

At times these devices are EVIL

A couple of points:

If the pilot can see the ground (airport/runway), then the idiot with the laser pointer can "see" him.

The pointers do spread out a bit, but not that much. The "aimer" (idiot on ground) usually uses a reflection on the windscreen to aim.

While driving on the freeway a couple of years ago (at night!) I had one of these pointed at me. It was VERY distracting, especially since you really don't know what it is, and it is very unexpected).

Everyone should try to drive into the blinding setting sun to have a similar effect. You end up lowering visors, putting up hands, moving papers, anything to get it out of the way. Now do that while landing a plane. Oh wait you weren't told about it in advance.

Counter measures (zapping back) might cure the problem (permanently!).

Oh, another thing, the wavelength (green) is where the eye is most sensitive (so we can tell different vegetation apart from the tasty animals we used to hunt).

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Coat

Training drill

Instead of banning the lasers

Wouldnt this be a good opportunity to practice arresting a terrorist with a missile launcher. If these guys can get into position to hit with a laser and have no trouble getting away the what about people with real weapons

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Boffin

DVD burner lasers

...wouldn't do anything - in a DVD burner they are focussed through a lens at a target a few mm away so they don't need to have accurate collimation. Take them out of the burner and remove the lens and they will be all over the place.

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Time for the rat brains

Didn't we have an article some time back that a rat brain can fly a plane (except for doing that "This is the captain speaking...." blurb before takeoff).

Those rat brains won't worry about shiny lights.

While I'm sure a laser is annoying for pilots, this really comes down to fear mongering. 9/11 hijackers use $2 box cutters! Grannies can't take knitting needles on planes! Terrorists use everyday articles! Ban everything!

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Coat

By the surplus of recent 'down under' stupidity...

...I've come to conclude that Australia is the new America.

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Boffin

Is see that school holidays are on.

"My physics teacher always said never to look at the dot of a laser, because even when reflected, monochromatic coherent light (as is generated by a laser and nothing else in the solar system) is bad for the retina."

... probably the same physics teacher whose head was recently blown off by GSM radiation?

I would think that "bad for the retina" is a function of watt/m^2, not of frequency distribution, but that's just me. Of course, you get different damage effects depending on the frequency used but that's another problem.

... come to think of it this would explain why lots of pointy-haired bosses spending their time in conferences staring at waving red dots seem fracking blind.

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Pilots need lasers

Pilots need lasers to shine back at the perpetrators. That way they at least get them back before the plane goes down.

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@Remy

It's still the case that *if* the spot had indeed grown to anything *like* a metre across, the energy density would be low, whatever the spectral characteristics.

The receptive pigments in the eye have a fairly wide sensitivity to different wavelengths. When it comes to bleaching those pigments, there's nothing magical about monochromatic light compared to wider-spectrum light which is still in the relevant range.

If you lit up a room with X lumens of wide-spectrum light, and then switched to X lumens of very narrowband light (as from a colour LED), the narrowband version wouldn't be obviously more dazzling merely by dint of its narrowband nature.

The idea of 300mW of light (of any frequency or combination thereof) lighting up an entire cockpit to dazzling intensity is simply nonsense.

300mW of even the most sensitively-received wavelength of green is still only ~200 lumens, and you can get that much light out of a decent LED torch there days.

Now, it's certainly the case that, compared to sunlight, laser light would appear to be coming from a near-point-source, so could be focussed onto a much smaller area of the retina than if someone were, for example, staring at the sun. The flipside of that is that any temporary blind spot is going to be very small, and some cockpit-based observer would need to keep their gaze steady on the bright spot, and you'd still have the issues of windscreens, sunglasses, etc all combining to reduce the energy.

Remember, we're not talking laser pointers 50/100m away, but more like kilometres. Beam dispersal is going to give an inverse-square effect, so being 10x the distance away is going to drop the intensity by a factor of 100.

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@Pete

Well, I certainly haven't tried it, but it seems to me that "hitting" a plane with a high-powered laser pointer isn't like firing a bullet. For one thing, the green lasers put out a visible beam, which would greatly aid in aiming. Plus the laser can be left on continually, so really all you'd have to do is anticipate with some degree of accuracy where the plane will be crossing and leave the laser trained on that spot. Finally, you're not "popping a balloon" with it, you're 'dazzling' the pilot. I imagine with the stress of trying to land, especially at night, a green flash in your eye, even for a split-second, would be most disconcerting. The cockpit windshield would scatter the beam somewhat, so a direct hit wouldn't even be necessary to project reflections all over the cockpit. And some of these are powerful enough that if an accurate enough 'hit' was scored, it could at least temporarily leave a bright spot on the pilot's retina, making a visual final approach difficult. Not to mention the nervewracking aspect of wondering if it's going to happen again, or if you're being targeted with the laser sight of some kind of weapon.

So all in all, I'd say this could be more of a problem than a simple easily-discountable myth. Anyone that's played with even a >8 mW laser pointer knows how disturbing it is when you accidentally get a reflection in your eye.

And yes, these people are criminals. Although banning the devices isn't the solution any more than trying to prevent forest fires by banning matches.

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Silver badge
Boffin

@ Pete

"As was pointed out, laser beams spread. It's only a few milli-radians but the wider the beam, the lower the brilliance and the less dazzling effect. The further away the wider the beam and the lower the light intensity again. Inverse square - the effect falls off rapidly."

If I'm reading you correctrly, you believe that there could be no momentary dazzle at all from a laser passing across the pilot's eyes at distance? Because, as I see it (sorry) having spots in one's eyes, suddenly, in the final five or ten seconds before touching a 250-ton aircraft to the ground could be... disconcerting, at best.

You only need enough power to disorient or distract the pilots, not completely blind them.

Also, I don't recall any mention of the timing of these events but, if they took place at night, with the pilots' pupils somewhat dilated from looking at dimly-illuminated controls in a dimly-lit cockpit so as to not affect their night vision, the dazzle-effect from a laser COULD be significantly increased.

"Next, passengers not seeing the effect: The size of the window is irrelevant. Provided you are close enough - e.g. in the window seat your field of view is as good as a forward-looking pilot's. There should be some reports from passengers"

If the idiot with the laser is on the glide path, with the plane coming towards him, then the passengers looking out the side windows - which by definition, are pretty much parallel to the direction of flight and, hence, the laser beam - would be looking PERPENDICULAR to the beam, as opposed to the pilot who is looking basically TOWARDS it. Big difference. As an experiment, if you have a generic laser pointer, hold it perpendicular to your line of sight and shine it at the wall. Can you actually see the beam as it goes through the air? Unless you are in a dusty/smoky room, probably not, because the light is all moving in one direction, and not bouncing out at every angle possible. You generally need to have a fog, smoke, or similar medium to see any "beam" effect, making it unlikely (not to say impossible, but highly unlikely) that the passengers would see anything at all from a laser aimed from the front.

"Third, to actually illuminate a pilot, as has been pointed out you have to be virtually on the flight path. Someone under the aircraft or to the side can't see the pilot and (more to the point) the pilot can't see them, even out of the corner of their eyes."

Pete, the pilots are LOOKING DOWN AT THE RUNWAY ON FINAL APPROACH. Therefore, they are also looking at anybody who is, say, near either END of the runway.

As an example, I would suggest that you fire up Google Earth and look up LAX. The runways at Los Angeles International airport all run, basically, east-west since the prevailing winds come off the land during the day and off the ocean at night. At one end of the runways is the beach (with a parking area), at the other end is the San Diego Freeway, and then a residential area, with lots of windows for stupid people to sit in, looking straight down the runway at approaching aircraft, the flight-crews of which may be looking directly at them on approach.

"Nearly there.... I still don't buy the ability of a person to hand-aim a laser onto a moving target over a mile away for any significant time. It's simply not possible and I defy anyone to prove otherwise. As a benchmark, the moon subtends an angle of 0.5 degree - you can't hand-aim a laser at that for any time, let alone the front of a plane - let alone the pilot's window - let alone the pilot's eye - even for a millisecond, even if they weren't moving."

Again, you ignore the fact that, if the target is approaching the shooter then it is, for all practical purposes, stationary - making keeping the beam on target significantly easier.

I carry a small 15-power telescope - pretty much the highest power scope that I can use hand-held - in my jacket pocket. If I am riding down the highway in a vehicle, I can keep signs over the highway directly in front of me centered quite easily, while looking out the side window at something as we pass it is much more difficult. In the first case the position of the target remains almost constant relative to me, while in the latter it is changing rapidly.

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Coat

Will Work ? Won't it Work ?

Has anyone ever thought that the never ending bickering as to whether or not lasers can be shone in the eyes of pilots this way is precisely why people go out and try it ?

I believe it used to be called "Experimental Scientific Method".

Mine's the one with the laser catalogue and a parking permit for T5 in the pocket.

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I've seen green laser from a plane

On approach to Melbourne I noticed a green laser and it did cause the scratches in the window to light up. It was also very easy to tell where the beam was coming from. If they ban pointing lasers at airplanes, will they also ban pointing lasers at cars or are the revenues too high from the IR lasers the police like to use?

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Paris Hilton

I have done this.

I have gone out to my local airport, with a scope, and a tripod. I stood outside the fence, and looked through the scope, to see if I could spot the windshield of the cabin.

4 planes landed, and four in a row, for at least a brief period, I was able to lock that scope on the windshield of the cabin. (There are legitmate, non-flashing things in people's eyes behind this, that had a lot to do with testing stabilisation technologies, and some auto-lock-on visualisation software.)

I was able to get 4 out of 4 MANUALLY. The software was able to keep the cabin of these planes in sight almost 100% of the time during approach. (Landing, the screen moves out of range.)

Don't bull**** me that it would be impossible, because if you strap 1, 2, 14, 25 whatever number laser pointers to that scope, you could cause a horrendous amount of light to flood the cabin, fairly coherantly.

Given my software, and this lovely USB-powered scope and software I have been working on, it would be very simple to drive up to my local airport in a van, park outside the gate, and have the computer light up every single plane as it tries to land.

That said, all of this gear, (including the laptop) cost me less than $1000. So I imagine doing it the old fashioned "manual" way, would cost a LOT less.

Paris, because even she could understand that "impossible" is simply a word used by those without enough imagination.

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funny thing is

one of 'my fav' sellers on ebay is based in Oz and they sell hi-power lazers

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not too terribly hard...

give me one of those higher powered numbers, a camera tripod, a SLR with a big zoom lens, and some electrical tape. betcha i could paint a target from quite a few miles with a little practice. even a moving one.

and after all, airliners aren't flipping all over the sky, they tend to follow nice, easy, stable flight paths. given the distances involved, the relative motion is actually quite low, seen from the perspective of the user. not too hard to follow that thing down, in truth, since it's only going to swing through a few inches of arc, when viewed from a distance.

ever notice how airliners seem to crawl across the sky at altitude? same thing.

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Flame

Not all attacks are real attacks

Firstly - the purpose of these powerful (actually only 5mW which have a range of about 5km - 7km tops) green lasers is for attaching to telescopes to help identify which area of the sky you are looking at when doing astronomy - perfectly legitimate.

While I agree that it is possible and extremely dangerous to target lasers at the cockpit of planes on landing approach, there seems to be a lot of articles around laser attacks that are plain (no pun intended) unbelievable.

For example there was another article here in Australia (Perth WA) only 2 weeks ago that claimed concerted attacks on the Police Rescue Helicopter which forced them to take "evasive maneuvers". In this case the Police heli used "sophisticated mapping software" to identify where the laser "attack" came from - arrests were made and the lasers confiscated.

However the article also mentions the area in which the Heli was flying (patrolling over Joondalup) and where they allege the attacks came from (Yokine)... a distance of over 15km (measured on Google earth). Chances are this was not a concerted attack on the heli (from over 15km - thats some pretty good aiming) and more likely the laser was being used legitimately and the heli just happened to fly into the (greatly dispersed by this stage) beam and the pilot has panicked.

While there are some random people who might try to see if they can hit a plane in the sky, unless the plane is landing and they are in the glide path, the chances of actually hitting and keeping it on the cockpit is pretty small and the chances of it actually dazzling the pilot with the amount of dispersion it would have (after say 10-15km away and at least 3km or 10,000 feet up) is minuscule.

Given the legitimate uses of the lasers, there is no reason for a complete ban... they should however declare laser exclusion zones along the runway glide paths... this has the effect of keeping the ban only to those areas where there use of the lasers pose an actual danger, and making it significantly easier to enforce (smaller area to monitor and easier to identify offenders).

IMHO while some of these supposed "attacks" are extremely dangerous (like on the planes landing in Sydney), many of the reports we are seeing in the news are completely unrealistic.

Of course even if they do a blanket ban, any group of extremists that want to bring a plane down in this way, will have no problem in a) getting hold of powerful enough lasers and b) making the attack from a vehicle by the side of the road and then just leaving the area before the authorities have the chance to arrive and nab them. So a blanket ban only inconvenience the general populace while still not protecting us from extremists from making a real attack and morons already already in possession of a laser avin a larf.

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Paris Hilton

Nope

I don't buy this for a second.

The closest I'll accept is that the pilots *might* be able to see the odd beam flash by them (probably dozens of yards away) as some idiot *tries* to focus on them but that's as far as I'll go.

Someone hitting a target moving in three dimensions from a mile away without some serious kit is too much to swallow.

Paris - 'cos she'll swallow anything

Cheers

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Silver badge

@ Pete: Lancasters

Apart from all the others who have rightly pointed out the many errors in your comment, I would like to add one point: 4171 Lancasters were lost during the second world war, quite a number of which to FLAK. I would not say 4171 losses supports your claim that hardly any were hit. To these losses add 2627 Halifaxes, 1970 Wellingtons, etc.

Also, when Ju 52s tried to land on Dutch airfields whilst the AA had not been suppressed, a huge number were shot down during their approach. Aiming a line of tracer (manually) is similar (though more difficult) than aiming a laser (lack of recoil, nice straight trajectory, etc).

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Gates Halo

Just shows you the new technology isn't safer than the old.

When I started out, we didn't use laser pointers in lectures, we had a big stick. But then someone pointed out that if you took a really big stick - military grade, not the short ones we used in lectures - you could poke the pilot with it and cause a crash, and demanded they were banned.

But this is obviously an enviromental protest group trying to shut down air travel - I mean, it's obvious, they're using GREEN lasers!

Bill icon to show how people are trying to shut down Microsoft by the use of yellow lasers.

And now if you'll excuse me, it's time for my morning medication.

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Distraction at crucial point.

At the distance from landing that the Pilot would be distracted by a flickering light or sudden flash or reflection, the pilot is a) transitioning from instrument to visual and b) monitoring for any light coming on to indicate possible problem.

It does not have to be powerful enough to blind or do anything, merley distracting the pilot at that crucial time is enough to cause a major incident.

ATC had reported several aborted landings because of this distraction.

What part of the danger or believability of this article do you not undrestand.

Why do most people need to have these even ordinatry power laser pointers for anyway. Pick up the kid in the street with one and I don't think he will be about to give a lecture at the local university. They are mainly used by mindless morons to dazzle oncoming traffic anyway.

BAN THEM.

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Durrrr

what about giving the two pilots a nice pair of mirrored raybans for their decent, unless we want to go lashing 14 year old into prison that is, but last i checked being a stupid little muppet wasn't an offence.

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Anonymous Coward

Effect on pupil dilation

The pilots are working in a dark environment and their pupils are fully dilated. What happens when bright light enters the eye is that the pupil contracts quickly and takes a while to open up again. During that time you feel pretty blinded. You can reproduce the effect by going out on a full-moon night, getting dark adapted and then looking straight into a small torch. Now, try to find the moon!

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Silver badge
Boffin

@Bryan

Mirrored raybans do not work, as pointed out above, they reflect every frequency indiscriminately, so there would be no change in visual contrast (which is most important in term of visual perception) just in overall light level. The laser protection goggles suggested before would be the better option, but the best ones, which work interference filters, have to be chosen to match the wavelength of the laser. As these may vary, the problem remains.

I really do not see what reasonable use high-power laser pointers have outside of a laboratory. Until I hear of some real use outside brainiac style fun (which can be real fun), I do not see why these potentially dangerous items (AT A RANGE, as opposed to a stick, you cannot out-run or dodge a laser) should be available without any control. It seems perfectly reasonable to work with a permit system: anyone (even a responsible kid with his own physics lab (they exist!)) should be able to get one, but the moment they use it to cause any kind of problems their permit is cancelled. If you are found using or owning one without a permit it should be confiscated.

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Pirate

Hotel Room attacks

This reminds me of the rumours that people were using them in Hotels to temporary blind people who had looked through the Peep Holes in Doors by shining them at very close range from the outside, after first knocking on the door to attract their attention.

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Joke

ILS

The trouble with automatic landing systems is that it is all too easy for a terrorist to take over a disused terminal computer and adjust sea level causing the plane to crash. I saw it in a documentary once ...

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Power and divergence - some figures.

The best laser you can get is a Spyder Wicked Laser, about 300mW (all 532nm) with a divergence of about 0.5mrad (all from memory - I forget the exact details). At 1km away that yields an intensity of 40uW/cm2 – you would certainly notice that; at 300 meters you would be dazzled (0.4mW/cm2), so there’s something in it.

Of course laser pointers are supposed to be limited to around 5mW although many on ebay are 25-50mW (of focussed laser, excluding unfocussed IR leakage) and use cheap optics, but they would still capable of severely dazzling at 100m away.

Anyone was had a green laser pointed at them should be very thankful it was a green laser. Be thankful the offender wasn’t clever enough to modify the laser to do something immeasurably more dangerous (anyone who knows how DPSS green lasers work will understand what I mean).

I shouldn’t say any more!

.

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Boffin

Red lasers safe (but green ones are obviously different)

When lecturing I used a red laser pointer on occasions. (I am now retired.) It was the usual little gadget about 3cm long that would fit on a key ring. When I was showing it to some friends in the pub one evening, a young lady shone it directly into my eye from just across the table. Having the whole of one side of my field of vision suddenly flooded with red light was startling, but there were NO after-effects, not even short-term dazzling.

I don't actually like laser pointers for lecturing. My hand is fairly steady, but the little red dot used to wobble about in a distracting way. Watching some of my colleagues trying to use them made me wonder if they had the alcoholic shakes, which was odd, since I thought I was the departmental lush!

The students had them as well. The favourite trick was to shine them on the projector screen in places where I didn't want to point while I was trying to use my own pointer. One of the little b*st*rds managed a direct hit on my eye from the back of the class. Again, no effect; it didn't even interrupt my flow, and I couldn't even tell who'd done it.

The best use for a red laser pointer is to aim it at the floor a few inches in front of a cat's nose, and keep it moving.

Obviously the high-powered green lasers that we see advertised are a different matter altogether.

"Boffin" since I used to be one.

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Coat

So if they ban lasers.

Then I guess everyone will move to super searchlights that plug into car lighters, the ones with the LEDs or something.

If they outlaw lasers, only outlaws will have lasers.

Sorry, had to say it.

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