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I've been admonished not to ever shine a laser into the night sky as it might "dazzle pilots" and potentially bring down airplanes. This seems kind of illogical for a number of reasons:

  1. If a plane is flying perpendicular to the earth, a laser from the ground would have to hit it at a significant angle, much more akin to pointing a bit higher than the horizon rather than straight up, for the actual pilot of the plane to see the laser output.
  2. While lasers can be deadly accurate, I find it hard to believe that any old Joe Shmoe can track the cockpit of an airplane at +10,000 feet, possibly miles away, and this would at the very least have to be deliberate.
  3. Most commercial airplanes fly for the most part (save takeoff and landing) on autopilot! Let's say you actually succeeded in temporarily blinding the pilot. The plane just keeps flying, as it exists in the 21st century and uses a computer.
  4. Unless you have something greater than a 1000mW laser (not easy or legal to acquire these days), won't the distance be too great to actually cause significant problems?

We were once playing on a military beach at night with a simple, store-bought green laser, shining it into the sky, when a scruffy old man approached us and reprimanded us for shining it into the sky, claiming that we might "dazzle a pilot." Is this just fallacy?

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You’ve already mentioned the conditions where lasers can be a hazard: take-off and landing. –  Konrad Rudolph Jun 2 '11 at 10:02
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You can buy a 1w laser at wickedlasers.com –  Razor Storm Jun 2 '11 at 17:42
    
A strange coincidence: I read your question a few days ago and thought that such a thing was very unlikely to happen. But today I read about a similar event that took place in Russia. Here's the source (translated from Russian by Google). –  Edwin Ross Jun 6 '11 at 10:54
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I suggest you take a flying lesson. It's cheap, fun, and educational. You might find you have a little more sympathy for pilots. The plane does the flying. The pilot just guides it. Nevertheless, when you're trying to put the wheels in the center of the runway, in the dark, not too soon and not too late, with gusty winds, and not just dropping it the last 10 feet, the last thing you need is a bright green flash in the face. –  Mike Dunlavey Jun 28 '11 at 19:26
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3 Answers 3

up vote 66 down vote accepted
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It is a real threat. Enough of a threat for the FAA to mail out a Pilot Safety Notice (Linked PDF). Let me explain why, as a counter to each of your points in the original question:

  1. First of all, planes bank and turn, so they aren't always perpendicular to the ground. Also, the Plexiglas material that aircraft windshields are made of further scatter and intensifies the dazzle effect on a pilot that happens to be sitting right up on the window. So you don't need to shine it directly at the pilot, just the cockpit.
  2. The greatest danger is not for high flying aircraft, but rather while aircraft are in critical phases of flight. That is not to say that you can't have an effect on higher flying aircraft. There is a property of lasers called divergence that will allow you to cover a fair area of the sky. Although, then the inverse square law takes over, so the power getting to a pilot at those distance normally wouldn't be a concern for most, although it may screw up night vision.
  3. You greatly overestimate the amount of time an aircraft is on autopilot. Generally, below 10,000 feet is where most professional pilots will take over from the autopilot in order to warm up for the landing phase. (This is a TTP for pilots.) It actually tunes you in for greater Situational Awareness (SA), and will have you looking out of the cockpit more than when on autopilot. Thus making you more susceptible to a laser dazzling effect.
  4. It only takes a small amount of light to screw up your vision for landing phases. This is especially dangerous during night operations. It is also intensified again by the scattering that you get from the Plexiglas as I mentioned in item 1. Add to that that green light is the most "dazzling" wavelength.

Specific effects as listed here are:

Distraction and Startle: This occurs when an unexpected laser (or other bright light) can distract a pilot during a night time take-off or approach/landing.

Glare and Disruption: This occurs as the intensity of the laser light increases such that it starts to interfere with vision; night vision starts to deteriorate.

Temporary Flash blindness: This effect is similar to that experienced when looking at a bright camera flash. There is no injury, but a portion of the visual field is temporarily knocked out. Sometimes there are ‘afterimages’.

And you are lucky that the old guy didn't call the Military Police on you. They have a procedure for reporting these incidents (called a SAFIRE). It has even happened with civilians.

New law to combat louts dazzling pilots over Birmingham with lasers pens (that's Birmingham in the UK).

PILOTS flying over the skies of Birmingham are facing a greater threat of being dazzled by a laser pen than almost anywhere else in the country, it has emerged.

The region is third in a ‘league of shame’ of hotspots for the crime according to a report by the UK Civil Aviation Authority.

Now they have introduced a new law to target the reckless offenders putting the lives of those in airliners and helicopters at risk.

Man arrested for trying to dazzle pilots with laser

(Reuters) - A man appeared in court on Tuesday accused of trying to dazzle pilots with a laser beam as they were landing at France's second-busiest airport Paris Orly, aviation authorities said.

"Several pilots complained and the man was arrested near the runway," a spokesman for the civil aviation authority said.

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 attack took place last Friday, involving at least four comparatively-powerful green laser pointers in the Bexley area of Sydney. Six passenger flights were affected, with air-traffic controllers having to re-route the planes.

"The use of these laser pointers against aeroplanes is unbelievably stupid and cannot be tolerated," Australian Home Affairs Minister Bob Debus told the Sydney Morning Herald.

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@Larian LeQuella, it was only a sarcastic remark. I was feeling highly skeptical of this, perhaps it was off-color, and I apologize for that. Nowhere in my question was I suggesting that I or anyone I know was or is planning on actually bringing down an airplane via a laser, I was asking if it was really possible, again, I was highly skeptical that it was. I'm really just asking whether me pointing a laser into the sky specifically NOT at airplanes was dangerous for any real reason. –  Naftuli Tzvi Kay Jun 2 '11 at 2:30
    
@Larian LeQuella, so is it reasonably safe for me to use a laser out in the mountains to point out constellations? –  Naftuli Tzvi Kay Jun 2 '11 at 2:32
    
I think the answer could be improved by some reference to laser strength. For example, in Australia, in a response to this problem, laser pointers stronger than 1 mW have been banned (en.wikipedia.org/wiki/Laser_safety). I'm not saying it is difficult to circumvent this ban or that the problem is solved, but this answer does not show that over-the-counter laser pointers are a problem. –  Oddthinking Jun 2 '11 at 4:41
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@Oddthinking The power of the laser isn't really that significant for DAZZLING. Especially when using a green one because of the wavelength. –  Larian LeQuella Jun 2 '11 at 10:31
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@TK Kocheran You should be okay if you are far away from any areas where aircraft commonly fly below 10,000'. Although, using a laser to point at starts on a clear night is probably not the best use of a pointer. ;) And I'll edit your question and my response. –  Larian LeQuella Jun 2 '11 at 10:32

From wikipedia Laser and aviation safety:

Under certain conditions, laser light or other bright lights (spotlights, searchlights) directed at aircraft can be a hazard. The most likely scenario is when a bright visible laser light causes distraction or temporary flash blindness to a pilot, during a critical phase of flight such as landing or takeoff.

The problem is that the people shining the lasers are doing it when the planes are getting near to landing, above suburban areas, so they aren't flying high above the clouds.

Although it may not effect the planes control it is a jerk thing to do because you can seriously damage someone's eyesight.

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Again though, this is in the context of deliberately shining a laser at an airplane albeit during takeoff or landing, right? –  Naftuli Tzvi Kay Jun 2 '11 at 1:46
    
@TK Kocheran - Right, but it answers your question. You're not shining the light from a boat in the middle of the ocean. Is it possible to distract a pilot with an over the counter laser? The answer is most definitely yes. –  xiaohouzi79 Jun 2 '11 at 1:59
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fair enough. Is it likely, though? Is pointing out constellations in the night sky a big risk, knowing not to aim the laser at airplanes? –  Naftuli Tzvi Kay Jun 2 '11 at 2:34
    
@TK Kocheran - I can't see you getting in trouble for that iff there wasn't a chance you could accidentally hit a low flying plane. –  xiaohouzi79 Jun 2 '11 at 2:59

According to this:

  • Permanent physical damage to the eye is highly unlikely (at time 3:48 in the video)
  • Even pointers can have effects that include startle, distract, glare, and 'flash blindness'
  • Strike is likely to be intermittent (small beam on moving target at long distance)

Maximum legal power for a green laser pointer is 5 mW (which can damage eyes if held on the same point of the retina for several seconds from within 50 feet); but distract can happen at 3,700 feet, and flash blindness at 1,200 feet.

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