Laser threat defence
 

In light of the news on Monday about a laser attack on a Virgin 744, a few of us have just spent our lunch hour chewing over the issue.

Apart from the usual sentiments involving locking up the perpetrators and throwing away the key, we were asking ourselves whether there's any technology that could be used to protect flight decks against laser light?

Offhand, I can't think of anything - filtered lenses exist, but they're only effective if you know what frequencies you're designing for. Block the windscreens and go IFR immediately? - would work but degrades lookout immediately so contra safety for other reasons.

Does anybody have any bright ideas?

G

How about modifying existing side window sunshades? Not sure how many attacks are aimed at the forward windows as opposed to the side views though....also how much visibility the crew would have once the shades are in place?

My favourite tactic is to swich the external lights off as soon as I see someone fiddeling around with this things. Yes, it is against the ANO but as a commander I can take all measures.... you know the stuff. Worked a treat so far. What the warrior can't see, he can not attack.

Maybe something using the technology of this welding helmet would do: https://www.youtube.com/watch?v=L5bMlI9ZHyY

In a previous job, hovering over and illuminating the perpetrator with the 30 million candlepower Nitesun used to give them a bit of a hint.

Blue flashing lights outside the front door was the second hint that a slight misjudgement on their part had been made.

Seeing as we live in an age of laser guided weapons would it not be possible to install reflective devices on the aircraft which would reflect the beam straight back at them?

Maybe. But that might give the miscreants some feedback on their aim. And some people might just get a kick out of being 'flashed back' by a passing airplane.

If that works reliably. What is the arrest rate for l@ser incidents? Unless you are dealing with some abject morons who keep lighting up successive planes, by the time one is reported, they have turned their pointer off and gone inside.

Something needs to be done to ensure that detection and arrest is nearly certain. Possibly a detector (camera) and GPS position that could automatically forward source location data to authorities on the ground. An iPhone/Android app on a phone positioned to look out the cockpit window might be sufficient.

I'm sure that something along the lines of an electronic auto-dimming welding mask glass could be made to work in cockpit windows. But it'd have to be totally reliable; after all you wouldn't want it going dark by mistake, might make the landings tricky...

It would be sad if something like that became the only solution to the problem (instead of import controls, prosecution of vendors and manufacturers, policing, etc).

It's well known that pilots are getting hurt. Are there any reports on passengers and cabin crew getting hurt? I guess that side on illumination isn't going to be as steadily aimed, but would probably still be damaging.

I'm sure there are systems in the military that can pinpoint the origin of laser light. Of course, civil aviation isn't warfare so the Geneva convention does not apply; you could have automatic gun aiming/firing integrated with such a system. It could be a specific variant, e.g. 747-400-130...

Illustration of the problem

Someone I worked with was involved in buying items like laser pointers from manufacturers in a certain large Far East Asian country. At one place he was shown a selection of laser pointers, and the labels on them (an indeed the demonstration) made it quite clear that the power output was far in excess of what was safe or legal in Europe.

When he explained this to the company and said he couldn't possibly buy them, their response was "no problem, we'll change the labels". Says it all really.

I'm pretty sure I've seen laser protection glasses that work by blocking a very specific wavelength. Because they take such a small chunk out of the spectrum, they have little effect on other light sources. Something like that might work for windshields. (I guess you might need to block more than one frequency based on the types of laser that need countering, but probably not more than a few.)

Or maybe you could use the welding helmet technology with a trigger that responds only to very specific frequencies, so the windshield (hopefully) wouldn't go opaque with each lightning flash.

Beam diameter.
 

PDR- From where does the beam angle spec come? What class of lasers have the .06 degree angle. Do cheaper and more expensive models have different angles?

PDR,


Without going into details that may help the bad guys, I think you need to take a look at the actual beam parameters from a moderate cost 1 watt laser pointer. Your required laser power estimate for damage at higher elevation is off to the high side by a huge factor..


I just ran your numbers thru a professional beam safety program, and if one small beam detail is improved by a factor of 10, the 1 Watt laser has a Nominal Ocular Hazard Distance far longer then your giving it credit for.


Especially if the inadvertent viewer is wearing eye glasses, and if the pointer user has added, or purchased a certain common modification.


However, I'm glad that your attempting the math instead of just repeating the common assumptions and rumors that are out there.



I work with laboratory lasers, and laser display projection systems for a living.


The real answer is to convince the Chinese government to stop the dumping of extremely low cost lasers onto the international market.
These low cost, hand held, lasers are a huge cash cow for Chinese optics companies. Most of which have some fairly shady owners, and have long been dumping optical parts at below market value.


Most of the time they are imported under fraudulent labeling to get around Customs...


As I work with Quality American and European systems, I can assure you these low cost lasers have taken a toll on the income, and sanity of legitimate laser users. Now they are slowly creeping into the cosmetic medical device market, via on-line marketing.


And Pilots, one tip from a laser professional. Avoid a possible secondary effect. Do your best NOT to rub your eyes after an inadvertent laser strike. A bright laser strike may strain muscles in the eye. Then if you drag a dirty hand thru the eye, you run a strong risk of pulling a muscle or irritating the soft tissue.


I got my start in lasers doing laser shows. The low cost lasers pushed many of us who had professional gear, who obtained the required permits, and insurance for outdoor shows out of business. Most of those low cost laser users are totally unaware or ignoring the fact that they need permits for un-terminated laser shows in airspace. Filing the paperwork generates NOTAMs, and there is a lot of math required to ensure safety compliance. That means that the companies who still try to be legal must turn down a lot of potential customers, as there is a delay, and mandatory review period with the local agency.


Most of the time, if the green 532 nm wavelength is blocked, that takes care of 90% of the offenders. However when you start getting into multiple wavelength blocking filters, the optical transmission of non-laser light goes way down. If you block the needed red band, you loose viewing much of the aviation standard red and green lighting.


I've been reading PPRUNE as a outsider for years, sorry that my first post has to be on such a disgusting topic.



Sim

Excellent analysis and gives serious food for thought. Given the number of attacks reported (and I have a strong suspicion there is actually significant underreporting) it would be helpful if the authorities issued some guidelines. PDR1's numbers suggest the risk decreases with height and above 10,000 feet on his numbers it looks low. But on final approach it could be significant. It appears you cannot reliably assess the power or exposure. But one option might be for a recommendation to get a medical check if targeted on final approach etc. Either way despite a little ill humour/stupidity that always seems to occur I think the wider discussion on this topic has been very helpful. Thanks to PDR1 and thumbs up to Scroggs.

I like Hahn's idea. I have been lasered five times so far, twice in the cruise. Trouble is these idiots can look on flight radar and listen to our RT and score a 'bingo' when we report the laser.

I was once lasered on the ramp by a passenger sitting in the aircraft next to us !?! I kid you not. :ugh:

Thanks PDR1, very interesting analysis. The chances of retinal damage would appear to be low?

PDR, you seem to be hooked on actual damage to the eye rather than temporary blinding/light spots and distraction. I can temporarily blind someone with a torch.

I will say again when I was subject to a laser attack I got a brief flash across the eyes and that was enough to render my eyesight essentially useless for several minutes. Don't you consider that dangerous?

Chesty

What height were you at?

I have been flashed with these things at 500ft in a helicopter and had no loss of sight at all, just annoyance.

Twice. First at about 3000' on departure. My FO essentially became single pilot as I couldn't discern the ASI properly and would've retracted the flaps too early if he hadn't stopped me.

The second at 36000' somewhere over Greece.

Both at night.

Chesty

Whatever hit you and caused you visual problems at 36000' was not a laser pointer held by a chav, believe me.

It definitely behaved like a handheld laser.

I didn't really care who was holding it at the time though.