Virgin Atlantic flight from London to NY returns after pilot hurt in laser incident
Join Date: Mar 2005
Location: UK
Posts: 17
Likes: 0
Received 0 Likes
on
0 Posts
I'm going to risk weighing in from the perspective of a background in physics (as well as avionics). Some of the physical observations here read to a physicist how aviation articles in the common press read to pilots. I think it's important for pilots to understand the mechanics behind this topic.
The power level of "high power" diodes purchased by consumers is typically in the tens to hundreds of milliwatts. Inexpensive visible light diodes which claim to be several watts are invariably mis-sold - I come across them now and again and measure them with a thermal effect laser power meter. I think it's reasonable to generalise that a laser pointer bought on eBay is unlikely to be more than a few hundred milliwatts of output power. It's worth noting that most (almost all) cheap visible light lasers are pumped by a much more powerful IR laser and if an appropriate IR filter is not installed the output power will be much higher than that of the visible component alone. IR light will pass the cornea and heat up the retina as easily as most visible light. Only as the wavelength moves into UV does the effect switch from retinal to corneal damage.
That's not to say that somebody who genuinely wishes to incapacitate a pilot might not have purchased a high quality visible laser with several watts of output power. It will have cost them several hundred pounds and I suspect the attackers under discussion here do not fall into this category.
At close range the output of even a low powered diode in the visible spectrum is very dangerous to sight. An 808nm (green) 50mW laser shone at close range into the eye for more than a few milliseconds will could inflict permanent injury. Laser pointers around 200mW are widely available and these could easily cause loss of sight.
Exposure is considerably reduced by distance. For incoherent light (such as a bulb) the power of the light reduces by the inverse square of the radius, which is not true for a perfectly coherent laser source. An ideal laser will have the same power at any distance because the energy does not diverge. However there are no ideal lasers, and the diodes one might purchase on eBay are very far removed from scientific grade. As the beam diverges a smaller area will contact the retina so the exposure is therefore a function of the radius of the beam at the distance of contact multiplied by duration.
At cruise altitude, or well into the climb, or early in descent, the distance of throw is substantial so the beam radius is large and the ratio of the beam area to the retina area is small. Furthermore the duration of exposure is likely to be short because it is difficult to manually track a moving target even with quite a shallow angle of incidence. As such this exposure is very unlikely to cause any damage to the retina - much higher exposures are experienced in night clubs when scanning the crowd with a moving laser (and those exposures are also calculated to be safe). I would suspect that the greater risk to flight safety in these circumstances is the surprise of the momentary flash of light, and the distraction that could result from this.
I would be far more concerned about exposure closer to the source - shortly after takeoff or on final approach. Beam radius at these shorter distances could be as little as a few centimeters even with a low quality source. There is certainly some risk to eyesight in these circumstances, whether that's permanent scarring of the retina or temporary dazzling (which can last for quite some time and is extremely disturbing). The latter effect is possibly why pilots are reporting prolonged exposure in the cockpit, even though it's unlikely that such tracking could be achieved manually. A 10ms exposure at relatively high power could easily dazzle a victim for several seconds.
In the case of the Virgin incident, I feel the co-pilot would be extremely unlucky to have suffered any permanent injury. That doesn't reduce the impact of the distraction and the distress that uncertainty of the consequences must have caused. I feel that flight crews should receive better training on these matters (beyond the occasional bulletin) which might better equip them for decision making during such events. During critical phases of flight it seems entirely appropriate to handle a laser strike as sudden incapacitation.
As for banning lasers - there's already categorisation and control for laser products. It's a matter of enforcement not legislation.
The power level of "high power" diodes purchased by consumers is typically in the tens to hundreds of milliwatts. Inexpensive visible light diodes which claim to be several watts are invariably mis-sold - I come across them now and again and measure them with a thermal effect laser power meter. I think it's reasonable to generalise that a laser pointer bought on eBay is unlikely to be more than a few hundred milliwatts of output power. It's worth noting that most (almost all) cheap visible light lasers are pumped by a much more powerful IR laser and if an appropriate IR filter is not installed the output power will be much higher than that of the visible component alone. IR light will pass the cornea and heat up the retina as easily as most visible light. Only as the wavelength moves into UV does the effect switch from retinal to corneal damage.
That's not to say that somebody who genuinely wishes to incapacitate a pilot might not have purchased a high quality visible laser with several watts of output power. It will have cost them several hundred pounds and I suspect the attackers under discussion here do not fall into this category.
At close range the output of even a low powered diode in the visible spectrum is very dangerous to sight. An 808nm (green) 50mW laser shone at close range into the eye for more than a few milliseconds will could inflict permanent injury. Laser pointers around 200mW are widely available and these could easily cause loss of sight.
Exposure is considerably reduced by distance. For incoherent light (such as a bulb) the power of the light reduces by the inverse square of the radius, which is not true for a perfectly coherent laser source. An ideal laser will have the same power at any distance because the energy does not diverge. However there are no ideal lasers, and the diodes one might purchase on eBay are very far removed from scientific grade. As the beam diverges a smaller area will contact the retina so the exposure is therefore a function of the radius of the beam at the distance of contact multiplied by duration.
At cruise altitude, or well into the climb, or early in descent, the distance of throw is substantial so the beam radius is large and the ratio of the beam area to the retina area is small. Furthermore the duration of exposure is likely to be short because it is difficult to manually track a moving target even with quite a shallow angle of incidence. As such this exposure is very unlikely to cause any damage to the retina - much higher exposures are experienced in night clubs when scanning the crowd with a moving laser (and those exposures are also calculated to be safe). I would suspect that the greater risk to flight safety in these circumstances is the surprise of the momentary flash of light, and the distraction that could result from this.
I would be far more concerned about exposure closer to the source - shortly after takeoff or on final approach. Beam radius at these shorter distances could be as little as a few centimeters even with a low quality source. There is certainly some risk to eyesight in these circumstances, whether that's permanent scarring of the retina or temporary dazzling (which can last for quite some time and is extremely disturbing). The latter effect is possibly why pilots are reporting prolonged exposure in the cockpit, even though it's unlikely that such tracking could be achieved manually. A 10ms exposure at relatively high power could easily dazzle a victim for several seconds.
In the case of the Virgin incident, I feel the co-pilot would be extremely unlucky to have suffered any permanent injury. That doesn't reduce the impact of the distraction and the distress that uncertainty of the consequences must have caused. I feel that flight crews should receive better training on these matters (beyond the occasional bulletin) which might better equip them for decision making during such events. During critical phases of flight it seems entirely appropriate to handle a laser strike as sudden incapacitation.
As for banning lasers - there's already categorisation and control for laser products. It's a matter of enforcement not legislation.
Join Date: Jun 2001
Location: Rockytop, Tennessee, USA
Posts: 5,898
Likes: 0
Received 1 Like
on
1 Post
I'm going to risk weighing in from the perspective of a background in physics (as well as avionics).
An 808nm (green) 50mW l@ser shone at close range into the eye for more than a few milliseconds will could inflict permanent injury.
All this time I thought it was infrared...
Are you maybe thinking of the very common green 532 nm DPSS laser with an 808 nm GaAlAs pumping diode?
Exposure is considerably reduced by distance. For incoherent light (such as a bulb) the power of the light reduces by the inverse square of the radius, which is not true for a perfectly coherent l@ser source. An ideal l@ser will have the same power at any distance because the energy does not diverge.
Last edited by Airbubba; 16th Feb 2016 at 17:59.
Join Date: Mar 2005
Location: UK
Posts: 17
Likes: 0
Received 0 Likes
on
0 Posts
Knowing the area where this incident reportedly occured quite well iwas curious to try and locate the area where the laser may have been shone from.
The track at the beginning of this thread shows a easterly departure from LHR 9R and assuming a standard Compton departure the captains estimate of about 8 miles from Heathrow puts the plane just south of Lego land themepark situated in the middle of the crown estate at Windsor. That would fit perfectly with estimates that the laser was 1-2 miles off to one side- ie to the north of track.
So I wonder if this was either an errant laser from a show or an employee testing/fooling around with one. They have a lot of laser shows there and it does seem a bit of a coincidence that this occured not just close to lego land but just the right distance to the south-so maybe just an error on an operaotrs or technicians part.
Not an ideal location for laser shows though being under SID tracks from both easterlyand westerly departures from LHR-presumelably they normally operate restricted power versions
The track at the beginning of this thread shows a easterly departure from LHR 9R and assuming a standard Compton departure the captains estimate of about 8 miles from Heathrow puts the plane just south of Lego land themepark situated in the middle of the crown estate at Windsor. That would fit perfectly with estimates that the laser was 1-2 miles off to one side- ie to the north of track.
So I wonder if this was either an errant laser from a show or an employee testing/fooling around with one. They have a lot of laser shows there and it does seem a bit of a coincidence that this occured not just close to lego land but just the right distance to the south-so maybe just an error on an operaotrs or technicians part.
Not an ideal location for laser shows though being under SID tracks from both easterlyand westerly departures from LHR-presumelably they normally operate restricted power versions
Join Date: Nov 2003
Location: Amsterdam
Age: 70
Posts: 159
Likes: 0
Received 0 Likes
on
0 Posts
There are problems with laser protection glasses/goggles, they are not perfect
Join Date: Dec 2013
Location: Aberdeen
Posts: 49
Likes: 0
Received 0 Likes
on
0 Posts
Pax Britanica
At last a rational explanation, thank you for researching that.
Would you mind sending that explanation to the BBC who are drooling at the idea of high powered l@sers in the hands of Windsor toffs bringing down aircraft.
Would you mind sending that explanation to the BBC who are drooling at the idea of high powered l@sers in the hands of Windsor toffs bringing down aircraft.
To the public I presume?
Any chance they might be undergoing any testing/training/other there currently before reopening in March?
Not at all suggesting this is the likely source of the laser, merely open to considering all possibilities at this stage
Any chance they might be undergoing any testing/training/other there currently before reopening in March?
Not at all suggesting this is the likely source of the laser, merely open to considering all possibilities at this stage
Join Date: Dec 2013
Location: Aberdeen
Posts: 49
Likes: 0
Received 0 Likes
on
0 Posts
Legoland opening
Sorry Airclues. the place is open:
February half term Junior Builder Week at the LEGOLAND Resort Hotel will take place from 12th — 20th February from just £140 per family!
February half term Junior Builder Week at the LEGOLAND Resort Hotel will take place from 12th — 20th February from just £140 per family!
I actually did wonder if the place was open this early not realsiing it was indeed half term hence my comments about 'testing'. What does interest me is what sort of lasers they use because the pics on the web look pretty spectacular but as I pointed out tis just to the north of the Compton SIDs for easterlies and ty much over it at the point where the 27R SID is in a right turn to pick up the track to Compton.
All that said I am sure legoland would have had to pass some kind of check on laser shows as it is so close to LHR
All that said I am sure legoland would have had to pass some kind of check on laser shows as it is so close to LHR
Join Date: Dec 1997
Location: Suffolk UK
Posts: 4,927
Likes: 0
Received 0 Likes
on
0 Posts
Some of you will know who I am. Most probably don't. However, I am the Captain in this event. I haven't been involved in Pprune for many years, but I used to be very involved, for which I offer apologies if appropriate!
It's been fascinating to read the speculation, and very interesting to read some of the factual postings in this thread. I don't take offence at those who question my decisions - all captains' decisions should be challenged and tested to see if they are indeed appropriate and proportionate, and this forum is as reasonable a place for that to happen as any.
For now, I won't be offering any significant justification or explanation. There's likely to be more investigations to be carried out, and I don't want to pre-empt, prejudge or influence any of those, or compromise my ability to speak freely to those who need to hear what I have to say. I'd just like to thank those who have some faith that I had some idea of what I was doing and why, and those who helped me get the job done both on the ground and in the air.
For those who have any relevant expertise, it was a red beam, not a green one. It was indeed reported as and when it happened. The pictures we got show its ground position (which wasn't Legoland as far as I can see), and will hopefully help those in the know to estimate its power and provenance.
As was reported in the news, the FO did receive retinal damage from what appeared to be a 'lucky' passing sweep, but it's not permanent and will heal fully. There was no visual impairment during the flight, but there was no way of knowing (for me) that that would continue to be the case.. The symptoms were slow in making themselves apparent. That's about all I'm prepared to say for now.
For the terminally pedantic, yes, I admit my Pan call was incorrectly phrased!
It's been fascinating to read the speculation, and very interesting to read some of the factual postings in this thread. I don't take offence at those who question my decisions - all captains' decisions should be challenged and tested to see if they are indeed appropriate and proportionate, and this forum is as reasonable a place for that to happen as any.
For now, I won't be offering any significant justification or explanation. There's likely to be more investigations to be carried out, and I don't want to pre-empt, prejudge or influence any of those, or compromise my ability to speak freely to those who need to hear what I have to say. I'd just like to thank those who have some faith that I had some idea of what I was doing and why, and those who helped me get the job done both on the ground and in the air.
For those who have any relevant expertise, it was a red beam, not a green one. It was indeed reported as and when it happened. The pictures we got show its ground position (which wasn't Legoland as far as I can see), and will hopefully help those in the know to estimate its power and provenance.
As was reported in the news, the FO did receive retinal damage from what appeared to be a 'lucky' passing sweep, but it's not permanent and will heal fully. There was no visual impairment during the flight, but there was no way of knowing (for me) that that would continue to be the case.. The symptoms were slow in making themselves apparent. That's about all I'm prepared to say for now.
For the terminally pedantic, yes, I admit my Pan call was incorrectly phrased!
Last edited by scroggs; 17th Feb 2016 at 01:42.
Join Date: Jun 2001
Location: Rockytop, Tennessee, USA
Posts: 5,898
Likes: 0
Received 1 Like
on
1 Post
For those who have any relevant expertise, it was a red beam, not a green one. It was indeed reported as and when it happened. The pictures we got show its ground position (which wasn't Legoland as far as I can see), and will hopefully help those in the know to estimate its power and provenance.
As was reported in the news, the FO did receive retinal damage from what appeared to be a 'lucky' passing sweep, but it's not permanent and will heal fully. There was no visual impairment during the flight, but there was no way of knowing (for me) that that would continue to be the case.. The symptoms were slow in making themselves apparent. That's about all I'm prepared to say for now.
As was reported in the news, the FO did receive retinal damage from what appeared to be a 'lucky' passing sweep, but it's not permanent and will heal fully. There was no visual impairment during the flight, but there was no way of knowing (for me) that that would continue to be the case.. The symptoms were slow in making themselves apparent. That's about all I'm prepared to say for now.
For the terminally pedantic, yes, I admit my Pan call was incorrectly phrased!
Join Date: Aug 2013
Location: PA
Age: 59
Posts: 30
Likes: 0
Received 0 Likes
on
0 Posts
Good Form scroggs!
i am wondering why the ac cockpit windows cannot be coated with the same material as military ac and equipment against laser.
In the military, many of the weapons systems use lasers for rangefinding and guidance, and I know the gunsights and windows/ports on tanks are coated to reflect the laser from direct and return, with no optical reduction.
They also use this coating on building windows so that a laser cannot be used to listen to conversations inside.
Edit: Found this on a lab website..
A laser is a light source that can be dangerous to people exposed to it. Even low power lasers can be hazardous to a person's eyesight. The coherence and low divergence of laser light means that it can be focused by the eye into an extremely small spot on the retina, resulting in localised burning and permanent damage in seconds. Certain wavelengths of laser light can cause cataracts or even boiling of the vitreous humor, the fluid in the eyeball. Infrared and ultraviolet lasers are particularly dangerous, since the body's "blink reflex", which can protect an eye from excessively bright light, works only if the light is visible.
egsc_h17....people pull them out of color laser printers..very powerful uncontained.
i am wondering why the ac cockpit windows cannot be coated with the same material as military ac and equipment against laser.
In the military, many of the weapons systems use lasers for rangefinding and guidance, and I know the gunsights and windows/ports on tanks are coated to reflect the laser from direct and return, with no optical reduction.
They also use this coating on building windows so that a laser cannot be used to listen to conversations inside.
Edit: Found this on a lab website..
A laser is a light source that can be dangerous to people exposed to it. Even low power lasers can be hazardous to a person's eyesight. The coherence and low divergence of laser light means that it can be focused by the eye into an extremely small spot on the retina, resulting in localised burning and permanent damage in seconds. Certain wavelengths of laser light can cause cataracts or even boiling of the vitreous humor, the fluid in the eyeball. Infrared and ultraviolet lasers are particularly dangerous, since the body's "blink reflex", which can protect an eye from excessively bright light, works only if the light is visible.
egsc_h17....people pull them out of color laser printers..very powerful uncontained.
Join Date: Dec 1997
Location: Suffolk UK
Posts: 4,927
Likes: 0
Received 0 Likes
on
0 Posts
Those are - to me at least - good points, and, as I'm the star player in today's teacup tornado, hopefully I'll get a chance to ask some pertinent and hopefully difficult questions which can be tossed into the melting pot as 'the authorities' temporarily agonise over what to do about this before something else moves their attention elsewhere.
If anyone with authoritative knowledge of mitigation measures which can relatively easily be applied to aircraft would like to PM me, I'm happy to include their contributions to the conversation. Please, I don't want - indeed I will actively reject - casual speculation, 'what-ifs', or otherwise non-expert inputs. I have a temporary but hopefully powerful opportunity to have a say, and I want to make sure that what I say has some weight. I'm well aware that terminal obliteration of the scrotes may be the ideal solution, as well as introducing the sellers of these devices to a man-eating monster of my choice, but it's unlikely I'll persuade anyone to legislate for that. Indeed, it's unlikely I'll persuade the legislators to do anything, and I'll leave that argument to the unions and other interested parties. Right now, I'm interested in what we as operators can do.
If anyone with authoritative knowledge of mitigation measures which can relatively easily be applied to aircraft would like to PM me, I'm happy to include their contributions to the conversation. Please, I don't want - indeed I will actively reject - casual speculation, 'what-ifs', or otherwise non-expert inputs. I have a temporary but hopefully powerful opportunity to have a say, and I want to make sure that what I say has some weight. I'm well aware that terminal obliteration of the scrotes may be the ideal solution, as well as introducing the sellers of these devices to a man-eating monster of my choice, but it's unlikely I'll persuade anyone to legislate for that. Indeed, it's unlikely I'll persuade the legislators to do anything, and I'll leave that argument to the unions and other interested parties. Right now, I'm interested in what we as operators can do.
Join Date: Sep 2014
Location: Canada
Posts: 1,257
Likes: 0
Received 0 Likes
on
0 Posts
i am wondering why the ac cockpit windows cannot be coated with the same material as military ac and equipment against l@ser.
Lamda Guard partners with Airbus to test laser interference solution
Halifax N.S. (June 4, 2014) Lamda Guard, a company based in Atlantic Canada, has signed an agreement with leading aircraft manufacturer Airbus to test a breakthrough innovation designed to deflect unwanted bright light or laser sources from impacting jetliner flight paths, and causing pilot disorientation or injury.
Lamda Guard’s innovative thin films utilize metamaterial technology on cockpit windscreens to selectively block and control light coming from any angle even at the highest power levels.
Halifax N.S. (June 4, 2014) Lamda Guard, a company based in Atlantic Canada, has signed an agreement with leading aircraft manufacturer Airbus to test a breakthrough innovation designed to deflect unwanted bright light or laser sources from impacting jetliner flight paths, and causing pilot disorientation or injury.
Lamda Guard’s innovative thin films utilize metamaterial technology on cockpit windscreens to selectively block and control light coming from any angle even at the highest power levels.
Join Date: Jan 2001
Location: Home
Posts: 3,399
Likes: 0
Received 0 Likes
on
0 Posts
Lasers are very effective against military aircraft which is one reason they are banned I believe. We certainly would never blind an enemy pilot of course. That would be unsportsmanlike.
In the military, many of the weapons systems use lasers for rangefinding and guidance, and I know the gunsights and windows/ports on tanks are coated to reflect the laser from direct and return, with no optical reduction.
They also use this coating on building windows so that a laser cannot be used to listen to conversations inside.
They also use this coating on building windows so that a laser cannot be used to listen to conversations inside.
You cannot stop an optical laser without affecting vision through a port.
Lasers used to listen to conversations are bouncing off the window and the vibration of the window causes doppler shift which is detected. Coatings won't change that one iota.
Join Date: Sep 2009
Location: 64N, 020E
Age: 56
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
"Safe" l@ser energies
Regarding the "safe" energy levels, does anyone know how what the assumptions of the pupil size are? If the "safe" estimates are based on a normal (day adaptation) pupil, wouldn't the resulting figure be an overestimate for a dilated (night adaptation) pupil?
According to wikipedia, a normal diameter of the entrance pupil is about 4mm, ranging from 2mm (bright) to 8mm (dark), so the underestimate might be with a factor between 4-16.
Just my SEK .10.
According to wikipedia, a normal diameter of the entrance pupil is about 4mm, ranging from 2mm (bright) to 8mm (dark), so the underestimate might be with a factor between 4-16.
Just my SEK .10.
Maybe we need to retrofit all aircraft with nuclear blast shades, as installed on the B52:
B-52 Cockpit for Sale, Boeing Stratofortress and other military aviation Memorabilia
That will surely keep our eyes protected?
B-52 Cockpit for Sale, Boeing Stratofortress and other military aviation Memorabilia
That will surely keep our eyes protected?
