Human World

Hand-held lasers aimed at aircraft doubled since 2009

The FAA recently announced that in 2010, there were 2,836 reported instances of hand-held lasers aimed at airplanes, about double the number from the previous year, and the highest number since they started keeping track in 2005. These incidents typically occur at night. In most cases, the sources are ordinary laser pointers, like those used for presentations, with a maximum power of 5 milliwatts. Most cockpit laser illuminations are brief flashes because it’s difficult to continuously aim a laser at an aircraft cockpit from a distance.

Still, at the very least, it is a distraction, especially during critical operations such as landings and takeoffs. At its worst, a strong laser beam flash, akin to a camera flash, could cause temporary loss of vision or reduced night vision. Eye injuries have even been reported by some pilots. To date, no aircraft accidents have been attributed to lasers aimed at cockpits, but anything that interferes with a pilot’s ability to do his or her job is a public safety matter that needs to be taken seriously. As a result, in February 2011, the U.S. House and Senate passed bills to make it a crime to aim at or illuminate an aircraft with a laser pointer.

On the evening of February 20th, 2011 a Southwest Airlines flight with more than 130 people on board was making its final approach to the Baltimore-Washington International Thurgood Marshall Airport. While the plane was at an altitude of about 2,000 feet, someone on the ground aimed a laser at it, sending a bright beam into the cockpit as the pilots were preparing to land. The aircraft arrived safely but the pilot and co-pilot reportedly suffered eye injuries. The FBI is offering a $5,000 reward for information leading to the arrest of the person responsible for the incident.

Just past midnight on March 10th, in Winnipeg, Manitoba, a 26-year-old man noticed a helicopter near his street. He decided to try out an inexpensive green-laser pointer he had recently bought, to see if he could “reach” the helicopter. His laser hit the pilot of that helicopter – a police helicopter – directly in her eyes. Within minutes, police were on the scene and placed him under arrest. He told Global News Winnipeg that he was just testing the pointer.

I wanted to test the range on that ’cause I see it goes out as far as my eyes can see. There’s something to test it on, so let’s do that!

I was doing it under the innocence of just trying to find something flashy to reflect against. Turns out that was something dangerous I shouldn’t have been doing.

The incidents in Baltimore and Winnipeg are typical cases involving commercial airliners and helicopters. It’s generally harder to track down people who target planes unless the vicinity of the airport is under surveillance, there are eyewitnesses to the incident, or the perpetrators are repeat offenders caught in the act. But for helicopters that fly low and have electronic night vision capability, it’s usually easy to pinpoint the location of a laser beam and alert police officers on the ground to the source of the beam.

Like the case of the Winnipeg man, most incidents of lasers targeting aircraft are by people playing with their lasers, unaware of the harm it could cause. Some are willful acts with malicious intent but, to date, none have been linked to terrorists.

There are several legitimate reasons for outdoor laser use. Small low-power pointer lasers, like the ones used for presentations, are a popular teaching tool for pointing out constellation patterns in the night sky during star parties. Powerful lasers are used for entertainment and scientific research.

The laser light show industry cooperates with the Federal Aviation Administration (FAA) to ensure that aircraft are not harmed by their lasers. Astronomers use powerful outdoor lasers as “guide star lasers” to monitor atmospheric turbulence close to a target they’re observing through a telescope; this is done so that image processing can remove the effects of atmospheric turbulence from the astronomical image. Observatories work within FAA guidelines, and planes are warned in advance to avoid the airspace over those observatories at night.

What does it look like to the pilot?
What a laser beam looks like in the cockpit of an aircraft depends on several factors. Lasers are not like flashlights. The beam of a laser is tight, and diverges at a much smaller rate than that from an ordinary flashlight (although it does diverge). A laser beam that starts just a few tenths of an inch in diameter could be several inches to a few feet in diameter at various distances, depending on the power of the laser and the degree of the beam’s divergence.

Color is also an important factor in the visibility of a laser beam – the eyes are most sensitive to green light in the dark. Therefore, a green laser beam will appear brighter than a red laser beam of equal power. Most of the time, when planes are targeted by lasers, pilots see only flashes of the laser beam because it’s difficult for a hand-held laser to point steadily at an object at such a great distance. But helicopters are generally closer to the ground, so it’s sometimes possible to maintain a steady aim on them.

As part of a government study, a series of simulations were created to demonstrate the effect of a small pointer laser’s illumination on a cockpit. A FAQ by Pangolin Laser Systems reports a case study of a green 5-milliwatt pointer laser by safety experts at Rockwell Laser Industries:

– Between 0 and 52 feet, the laser created a “blink reflex,” which means that the eyelids automatically shut to protect the eyes.
– Temporary “flashblindness” and afterimage, like that experienced from a camera flash, occurred at a distance range of 52 to 262 feet.
– Between 262 and 1,171 feet, the laser caused a glare that partly obscured the pilot’s outside view and affected his or her night vision.
– From 1,171 to 11,712 feet, the laser created a distraction.
– Above 11,712 feet, the laser was either not visible or was indistinguishable from other lights on the ground.

In many cases, the people responsible for so-called laser attacks on aircraft have been unaware of the effect it has on pilots. Although there have been cases of perpetrators out to willfully cause harm, none have been tied to terrorists. Fortunately, to date, there have been no aircraft accidents due to laser beams affecting pilots’ flight operations during critical maneuvers such as landings and take-offs.

Whatever the reasons may be for pointing a laser at an aircraft, the potentially dangerous outcomes are driving law enforcement to aggressively crack down on it. Whether a laser beam causes an annoying distraction, disrupts the pilot’s night vision, reflects off the glass to partially obscure the view out the window, or in the most severe case, causes momentary “flashblindness” and afterimages, it can lead to potentially dangerous situations that jeopardize the aircraft and people on the ground.

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Mark Changizi: Why human eyes see in color

March 15, 2011
Human World

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