Lasers and airplanes

just as a note of reference...5mW lasers are supposed to be the legal limit without some type of permit, however, myself and several friends have all purchased 15mW-50mW models with no inquiring as to our qualifications. so technically they're regulated, but distributors i guess dont really have any regard for that...

as for your situation, that's too bad that people are that ignorant. glad you're ok though and you handled the situation without any incident.

bobkrech said:

The same brightness as a megawatt lightbulb at the same distance is a bit more than an annoyance to a dark adapted eye.

Click to expand...

Bob,

For an omni-directional source the power per unit area decreases by the inverse of the distance squared. So a 1 megawatt lightbulb at 3 miles (15,840 feet) would appear as bright as a 100 watt lightbulb at 158 feet, or a 1 watt lightbulb at 15.8 feet. That's not really that bright. However, maybe it does look bright for dark adapted eyes as you said.

Did I do the math right, or am I off by a few orders of magnitude?

Dave

Sandy H. said:

Can anybody give an approximate power for the following lasers?

Pocket Laser Pointer, Surgical Laser, Grocery Store Scanner, Indoor/Outdoor "Laser Show", Metal Laser Cutter and any other lasers that are common knowledge for the average Joe.

This is just for curiosity. I honestly never knew there are lasers that could paint a plane in the sky or that people would do that sort of thing.

Glad you're fared OK Mach7.

Sandy.

Click to expand...

Legal laser pointers and grocery store scanners are 5 mw and below. All laser pointer are supposed to be eye safe Class I & Class II. Some of the cheap, illegal Chinese laser pointers discussed here are Class IIIA and IIIB and Class IV lasers. (It's not that the laser themselves are illegal, it's just the use, although many of these lasers do not have the legally required interlocks.)

Light show lasers can be Class IIIA, IIIB, or even Class 4 lasers before the expanding and scanning optics, however the integrated equivalent eye light dose should be below the Class I level unless the airspace and building backdrops are cleared.

Surgical lasers are typical in the 10's of watts range. Class IV.

Metal cutting lasers are it the kilowatt to 10's of kilowatt range. Class IV.

Class I laser will not cause eye damage if view directly although direct viewing will be painful.

Class II laser will not cause eye damage unless you stare at the beam for a very long time and it will be very uncomfortable to do so.

Class IIIA and IIIB laser can cause immediate eye damage if viewed through magnifying optics, but the reflections will not but will be painful.

Class IV laser will cause immediate eye damage as will the reflections.

bobkrech said:

The same brightness as a megawatt lightbulb at the same distance is a bit more than an annoyance to a dark adapted eye.

Click to expand...

Thats not that bright. With some quick calculations, thats about as bright as a 100W bulb at approx. 150 feet.

Sandy H. said:

This is just for curiosity. I honestly never knew there are lasers that could paint a plane in the sky or that people would do that sort of thing.
Sandy.

Click to expand...

Oh sure. How do you think laser guided munitions work!

r1dermon said:

just as a note of reference...5mW lasers are supposed to be the legal limit without some type of permit, however, myself and several friends have all purchased 15mW-50mW models with no inquiring as to our qualifications. so technically they're regulated, but distributors i guess dont really have any regard for that...

as for your situation, that's too bad that people are that ignorant. glad you're ok though and you handled the situation without any incident.

Click to expand...

Permits are not required, and they are not regulated. It's the use that's illegal, as are the lack of interlocks, however there is no real regulatory strength to the law.

DaveHein said:

Bob,

For an omni-directional source the power per unit area decreases by the inverse of the distance squared. So a 1 megawatt lightbulb at 3 miles (15,840 feet) would appear as bright as a 100 watt lightbulb at 158 feet, or a 1 watt lightbulb at 15.8 feet. That's not really that bright. However, maybe it does look bright for dark adapted eyes as you said.

Did I do the math right, or am I off by a few orders of magnitude?

Dave

Click to expand...

I should clarify that it's the lamp's optical output, not electrical input. A simple incandescent lamp only converts about 10% of it's electrical energy into visible light. A green laser emits at 532 nm and has a sub nm bandwith while the visible spectrum runs from 400 nn to 700 nm. To get the same green intensity as the laser I used as an example, you would need an ~ 1 gigawatt electrical input light bulb (electrical power input equal to the electrical output from a large power plant) with a sub nm bandpass green filter. That's really bright.

I don't know how else to explain it. Lasers are really bright.

Bob

Take it from me, Bob is correct lasers are REALLY bright!

Mark,
I'm glad you guys were allright up there. My Dad flew for the airlines his entire career life. That's serious stuff.

For the legal issues? It does not matter if there is a speciffic law or not. The Feds will find a law that fits this crime when it could cause mass casualties. They will bury someone who does this, and I'm glad. This has made the news, and it was said that if anyone did that, that they would hunt them down, lock them up, and they would be there for a very long time.

This is comparable to those idiots who didn't heed the warning about putting ANY kind of powder in envelopes and sending it through the mail. There always has to be some fool who will try it. If somebody goes and threatens the security of this country or does anything that could result in great loss of life they are gonna pay dearly for it.

Not only could that have caused a crash. It could've started panic on that plane and caused passengers to think they were being targeted.

Rock_It said:

Mark,
I'm glad you guys were allright up there. My Dad flew for the airlines his entire career life. That's serious stuff.

Click to expand...

Laser pointers aside, there are far more accidents to us on the ground when some old grandmom drives down the highway with her high beam lights, especially on narrow two-lane roads.

Laser pointers and airlines are getting all the media attention these days, but i don't know how many close calls i've had when some jerk-off comes barreling around the corner on a dark road with his high beams on giving me instant glare blindness.

There is a state highway garage near here with a security light bright enough that I have a hard time seeing the road any distance in front of me at night.

DaveHein said:

However, maybe it does look bright for dark adapted eyes as you said.

Click to expand...

For a comparison of dark adapted vision to daytime vision, at our observatory we have a bathroom with a red light (red preserves night vision). If I go in during the day out of the sunlight, I can barely even see what I'm doing.

When I come in out of the dark, however, that same light actually hurts my eyes a bit until I adjust to it. And this is the reflected light off the walls - not looking right at the bulb.

Of course, astronomers adjust to as close to as pitch black as possible, I'd imagine a cockpit has a bit more light than that.

Looking at planets like Jupiter or Saturn though a telescope can also cause discomfort to dark adapted eyes.

Nerull said:

For a comparison of dark adapted vision to daytime vision, at our observatory we have a bathroom with a red light (red preserves night vision). If I go in during the day out of the sunlight, I can barely even see what I'm doing.

When I come in out of the dark, however, that same light actually hurts my eyes a bit until I adjust to it. And this is the reflected light off the walls - not looking right at the bulb.

Of course, astronomers adjust to as close to as pitch black as possible, I'd imagine a cockpit has a bit more light than that.

Looking at planets like Jupiter or Saturn though a telescope can also cause discomfort to dark adapted eyes.

Click to expand...

How about the full moon
Cheers
fred

Though a telescope? Its blinding. The full moon completely ruins any night vision you had in whatever eye you use.

It also keeps you from developing good night vision just by being in the sky, limiting the stars you can see. In addition, the light gets scattered by the atmosphere, making the whole night sky brighter, further limiting what you can see.

Astronomers are allergic to the moon, as we like to say. Thats when we catch up on sleep.

Nerull said:

Though a telescope? Its blinding. The full moon completely ruins any night vision you had in whatever eye you use.

It also keeps you from developing good night vision just by being in the sky, limiting the stars you can see. In addition, the light gets scattered by the atmosphere, making the whole night sky brighter, further limiting what you can see.

Astronomers are allergic to the moon, as we like to say. Thats when we catch up on sleep.

Click to expand...

I agree. It's something i found out the hard way
Cheers
fred

DaveHein said:

Maybe the culprit was actually on the plane. It may be that the beam reflected off of a shining part on the wing, such as a motor cowling. Or the plane may have one of those vertical structures at the end of the wing (a winglet?) that could serve as a reflective surface.

Dave

Click to expand...

Wow. Great "outside-the-box" thinking. You're ready for CSI: Austin.

As far as the dispersion of the beam, I have a better appreciation of military laser designators "painting a target."

O/T: Alaska Airlines Keep an eye on your jack-screws. That incident still freaks me out to think about.

How about the full moon ?

Click to expand...

No self-respecting astronomer looks at the sky when the full moon is out!

However, i know at extremely dark sites i've been to (i.e. Cherry Springs, PA, or locations out west in Utah, New Mexico), even Jupiter is enough to blind
you during your observation session and become a major annoyance.

Alaska Airlines Keep an eye on your jack-screws. That incident still freaks me out to think about.

Click to expand...

Regardless of these EXTREMELY RARE incidences, air travel is still the safest way to go.

You think, "well, what if this jack-screw fails or some other part fails."

However, do you ever think of "what would happen if you a blow-out in my car doing 65 MPH down the highway! I'm sure thats magnitudes more common that a critical flight component failing during flight and has the possibiltity of being just as devastating.

eastvolt said:

However, do you ever think of "what would happen if you a blow-out in my car doing 65 MPH down the highway! I'm sure thats magnitudes more common that a critical flight component failing during flight and has the possibiltity of being just as devastating.

Click to expand...

Did that Monday. Turned out okay though. I HATE changing a tire on the side of the freeway (when you're in hurry to get to the airport - of course). The sidewall ended up with a 3 inch split in it. I don't know if it dryrotted or if I hit some construction debris... Turned a short (ish) trip to drop off a friend into an all-day project.

Ohio, where we only have two seasons. Winter and Construction.

Peartree said:

Ohio, where we only have two seasons. Winter and Construction.

Click to expand...

And they blend together...I live about 10 minutes from the I70-I75 interchange. They've been working on it for about two years now, and have just extended the completion date to May, 2010...Which is AFTER they start working on the I75-OH4 interchange about 5 miles south...Both of those are on my daily commute...I need a jet pack...

eastvolt said:

Regardless of these EXTREMELY RARE incidences, air travel is still the safest way to go.

Click to expand...

Really? I remember learning that in terms of MILES Traveled that is correct. But I also remember that in terms of HOURS OF EXPOSURE that is not the case. I can't find the stats right now...

Anyone else have this data?

uncle_vanya said:

Really? I remember learning that in terms of MILES Traveled that is correct. But I also remember that in terms of HOURS OF EXPOSURE that is not the case. I can't find the stats right now...

Anyone else have this data?

Click to expand...

Actually, either stat looked alone really is meaningless. You have to look at the whole picture when making cross-modal comparisons. For example, commercial aviation statistics include just that - commercial aircraft. It does not include general aviation in its statistics. However, the numbers often used by the NTSB and other organizations for vehicular accidents includes both personal AND commercial vehicles in its stats. That alone can skew the results for vehicular travel making it appear safer than it does (fatality rate for commercial vehicles - especially considering the amount of miles traveled and the fact the larger vehicles provides more protection) is much less than general vehicular travel.

Precisely why in many states (if not all) seatbelts are not required in commercial buses.

Peartree said:

Ohio, where we only have two seasons. Winter and Construction.

Click to expand...

And isn't the unofficial state symbol the orange/white construction barrel?

WAC_Hal said:

And isn't the unofficial state symbol the orange/white construction barrel?

Click to expand...

Nope, sorry, the orange/white barrel's are the State Flower...

Johnnie

Peartree said:

Ohio, where we only have two seasons. Winter and Construction.

Click to expand...

As opposed to colorado, where we have all 4 seasons:

Almost winter
Winter
Still winter
Construction