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Sunday, May 1, 2011

Seeing the Light 

Laser pointer attacks are a growing threat to aviation, with the majority of incidents impacting helicopters, according to FAA. But can these devices cause permanent damage to pilot eyes?

By Ernie Stephens, Editor-at-Large

Type-II laser pointers, such as this one, can project a 1–4 m/W beam as far as 800 feet. Many communities around the world have passed laws prohibiting them from being pointed at people, land vehicles and aircraft.

I suppose it was 1986-ish when I held a laser device in my hand for the first time. It was mounted on an assault weapon a fellow officer in the Special Operations Division had recently been issued. One of my jobs, at the time, was to fix almost everything electronic the division owned, such radio headsets, wiretap equipment, and anything else that had those pesky electrons running through it. Truth be known, once I repaired the device’s broken switch, I spent a few minutes targeting or “indexing”—the proper tactical term—various “threats” in my office with this hot piece of new technology. I pointed it at my bulletin board, stuff on my shelf, and even my buddy Mel, when he came through my door. I think I even asked him to puff some cigarette smoke into the air, so I could get the full effect of the red beam cutting through the air. “Cool” was probably the word I used.

Fast-forward to about 2002. My partner Mike and I were conducting a search for a robbery suspect one night when a red light swept the cockpit of our helicopter. It wasn’t very intense, but two things immediately crossed my mind. The first was the label on the laser pointer I owned that read: “Danger! Laser Radiation. Avoid Direct Eye Exposure.” Second, and most important, was that the laser could be attached to a weapon that someone was about to use against our police helicopter. Regardless of the source, I banked hard and away from the high-rise building I suspected it was coming from, and quickly left the area.

Today, laser devices are everywhere from the battlefield to the boardroom. (Heck, I probably have five of them myself.) But what has surprised me is the number of laser pointers that I’ve seen in the hands of children and young adults. Vendors sell them for as little as $10 at the beach, and more expensive ones can be found at specialty kiosks in many large shopping malls. And while using them to point to things in a learning environment is the most common use, somewhere along the line, pointing them at aircraft has become a popular pastime for some. The reasons I’ve come across have ranged from people just trying to see how far and well they can aim them, to troublemakers intentionally trying to harass the pilot of a flying machine.

Class Max Power (mW) Logotype Warning Label Example
I 0.0004 None Required None Required Video players, CD players and printers
II 1 CAUTION Laser Radiation – Do Not Stare Into Beam Laser pointers
IIIA 5 CAUTION (Irradiance <2.5 mW/cm2) Laser Radiation – Do Not Stare Into Beam or View Directly with Optical Instruments Light show and laboratory lasers
DANGER (Irradiance ≥2.5 mW/cm2) Laser Radiation – Avoid Direct Eye Exposure
IIIB 500 DANGER Laser Radiation – Avoid Direct Eye Exposure to Beam Many research and some printer lasers

Laser pointers have been harassing aircraft for longer than many people realize. FAA’s Western Pacific region received more than150 reports of “laser hits” between January 1996 and July 1999. By 2010, there were more than 2,800 laser incidents reported to law enforcement authorities and the FAA by pilots of all kinds of aircraft. Incidents involving airliners on final approach tend to receive the most media attention, but several studies commissioned by FAA, including DOT/FAA/AM-01/7 (April 2001), indicate that most laser/aircraft encounters involved helicopters, probably because they fly at lower speeds and altitudes than their fixed-wing counterparts.

Many pilots (me included) have become very uncomfortable with the notion that our kind of aircraft is such a frequent target of laser pointing incidents. They fear being temporarily blinded during a critical phase of flight, but their biggest fear is suffering permanent eye damage from having a light shined directly into their eyes. According to experts, however, the latter issue may not be an issue at all, at least not for a pilot in flight.

Although stronger laser devices are capable of burning holes in paper and popping balloons, ophthalmologists—medical doctors who specialize in eye disorders—seem to agree that a person has to be within 10 feet of a common laser pointer to sustain any damage to the eye.

“I’m not aware of any damage done to pilots,” said Dr. K. Bailey Freund, a board-certified ophthalmologist and partner at Vitreous Retina Macula Consultants of New York, a Manhattan-based eye practice. He also serves as a spokesperson for the American Academy of Ophthalmologists. The chances of permanent eye injury are not great, he said, because of the distance between the laser source and the pilot.

A “scotoma,” is an area of diminished vision that may result from prolonged, close-range exposure (less than 5 feet) to a Type-II laser pointer, the most common kind available to the general public. It is caused by a retinal burn from the beam, and may be permanent.

Freund reports that the only incidents of permanent eye damage from laser pointers that he has knowledge of, resulted from people—young children at play, mostly—shining them into their own or a playmate’s eyes from within 10 feet, and doing so over a couple of minutes, depending on the power of the device. Such exposures resulted in a “scotoma,” the medical term for a blind spot. Sometimes the damage is temporary, but the strength of the beam and time the victim is exposed to it can result in a permanent scotoma, which will cause the patient to see a dark spot all the time.

The most common issue reported by pilots who were hit with laser pointers was temporary blindness; the same kind one would experience if a high-intensity spotlight was shined in their eyes, or a camera flash went off at close range. Once the light is gone, pilots experienced a sort of temporary blindness.

When I began writing this report, I thought it would be helpful to capture the effects of a laser hit with my camera. After all, while laser attacks are no longer rare, there are plenty of pilots who have never found themselves on the harmful end of one, and were curious to know what it’s really like.

I was a few seconds into figuring out a way to be airborne with my camera—with someone else doing the driving, or course—and make sure they were looking away as an assistant indexed us with a beam for the photo. But then, three things occurred to me. First, it’s foolish to subject an aircrew to this kind of hazard, regardless of how well orchestrated it might be. (After all, we know about Murphy’s Law!) Second, I can do the same thing without being in the air, and get the same effect. And third, there is already local legislation in many places out there that forbids anyone from intentionally pointing a laser device at an aircraft in flight. In fact, an amendment to make it a federal offense to aim a laser at an aircraft for any reason was passed by the Senate in a 96-1 vote earlier this year. It is expected to become law before the end of the year.

So, in an effort to play safely, as well to remain within a wide interpretation of the law in the jurisdiction I set this up in, I choreographed a laser pointing scenario using a ground vehicle instead of a helicopter, and I played the role of a bored kid trying to “laze” a low-flying helicopter. (See images below.)

The view looking down a runway before (left) and during (center) a direct “hit” from a common, Type-II laser pointer located 100 feet downrange. The image on the right simulates the temporary, but hazardous effects after the lighlight is removed. Note: For safety and legal reasons, an aircraft was not used for this demonstration.

I waited until dark, and with the kind permission of Lee Sheik, the manager of College Park Airport (CGS) in Maryland, parked my truck at the approach end of Runway 15. With my digital single-lens reflex camera perched on a short tripod in the back seat, I took a natural-light shot out of the front of the vehicle and down toward the departure end. Next, I set the shutter for a timer-controlled release to make sure the camera would be perfectly still for the shot. I then fired the beam from a typical, commonly-available Type-II laser pointer at my truck from approximately 100 feet downrange, sweeping the entire windshield area. The three-photo set accompanying this article shows the results.

The first image shows the view down the runway. There’s enough natural light to make out the runway centerline, the edge of the runway itself, and some of the scenery off to the sides. The center image shows the blinding effect caused by the beam. It closely depicts the split-second glare or “red-out” a person experiences when the beam sweeps past their eyes. At the altitudes and distances pilots will be from the majority of commercially-available pointers, nearly everything outside and inside of the aircraft, including instruments, will be impossible to see. But again, experts say there is no risk of permanent eye damage at such distances. And even if the beam is from a more powerful Type-IIIA device, Freund advises that normal reflex action will cause the viewer to turn away or close their eyes before any serious damage at such ranges can occur.

The final image is a simulation of the scotoma left by the light generated by the laser beam. The scotoma caused by the laser beam will continue to black-out the pilot’s view of the outside world, as well as the aircraft’s instruments. The pilot will, for all practical purposes, be flying blind, as if in an inadvertent IMC condition with no instruments, until normal vision slowly returns.

The laws prohibiting pointing laser beams at pilots—and even motor vehicle operators—are popping up on the books around the world, partially because of the problems caused by the light while it’s in the pilot’s eyes, but also because of the after effects, which usually last longer than the laser attack itself. Even an evasive maneuver to exit the threat area, or to abort an approach, would be nearly impossible to execute with any degree of safety until the light is gone and the scotoma has worn off. Visual acuity will gradually improve, but it will be several minutes before it returns to the level it was prior to the hit. That’s a long time, especially in a single-pilot situation.

For now, the tactics for dealing with laser attacks resembles those used in any situation where a pilot inadvertently looks into something bright, like the landing lights of an on-coming aircraft, the white phase of an airport beacon, or a flashlight accidentally turned on inside of the aircraft: Try to get the light out of one or both eyes, and decide if the environment and phase of flight dictate continuing or aborting the maneuver. Just remember that some laser pointer attacks will be too sudden, too intense, and too short-lived to execute much of a planned response to, outside of an inherent reflex to blink. But one response that is always good is to report the incident to the authorities.

Meanwhile, rest assured that according to the experts, the kinds of laser pointers involved in the vast majority of attacks will not cause any long-term damage to the eyes of a pilot in flight. They won’t be close enough to the aircraft to be of any physical consequence.

Class Max Power (mW) Logotype Warning Label Example
I 0.0004 None Required None Required Video players, CD players and printers
II 1 CAUTION Laser Radiation – Do Not Stare Into Beam Laser pointers
IIIA 5 CAUTION (Irradiance <2.5 mW/cm2) Laser Radiation – Do Not Stare Into Beam or View Directly with Optical Instruments Light show and laboratory lasers
DANGER (Irradiance ≥2.5 mW/cm2) Laser Radiation – Avoid Direct Eye Exposure
IIIB 500 DANGER Laser Radiation – Avoid Direct Eye Exposure to Beam Many research and some printer lasers
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