Lasers and Airplanes: Common Misperceptions
By David Lytle
Jan 10, 2005: The recent wave of reports of US aircraft illuminated by lasers highlights the need for the public and US Safety officials to better understand the nature of laser technology. A number of inaccurate statements have been repeated by US government officials and the media regarding the hazard level posed by lasers.
A joint memo by the US Dept. of Homeland Security and FBI, for example, recently warned that terrorists might use inexpensive, off-the-shelf lasers to blind airline pilots in flight. Safety calculations performed using internationally accepted exposure levels show this is not the case. The energy necessary to cause a permanent eye injury at a distance of 1,500 meters would require in excess of 15 watts of laser power and the use of specialized optics to focus the beam. Such a laser setup would cost upwards of $50,000 and would need a highly skilled operator.
Laser Shows Strictly Regulated
This type of laser projector is not used or sold by any laser light show company. Moreover, anyone who purchases an entertainment laser projector in the US must obtain a variance form the Food and Drug Administration before purchasing the unit and must provide prior notice of all laser shows. Outdoor shows comply with strict rules that keep laser beams away from airports and mandate the use of human "spotters" to monitor the skies and shut down the laser show if a plane approaches the display.
Although federal authorities initially
sounded a warning about terrorists, an FBI spokesman subsequently
stated that the rash of recent illuminations of aircraft by lasers
all involved pranks. He described the exposures as a "nuisance."
Even a spokesperson for an association representing airline pilots
discounted the threat lasers posed to aviation, saying lasers
would not be a highly effective weapon against aircraft.
A New Jersey man was recently arrested by the FBI for allegedly illuminating the cockpit of an aircraft with a laser pointer. The aircraft was traveling at a speed of 250 knots at an altitude of 3,000 feet. The man was using a commonly available, over-the-counter laser rated at 5.0 milliwatts of power. It would require the combined output of several thousand of these lasers, all focused in a single beam, to cause eye damage to a pilot flying at the distance involved.
The common 5.0 milliwatt laser pointer cannot cause eye damage beyond fifty feet, and at a distance of 3,000 feet it is classified as a distraction. Laser pointers, even at distances of a 300 feet, constitute a hazard (under the worst of circumstances) similar to the glare from an oncoming car's headlights or the flash from a point-and-shoot camera. While this can impair the vision of some people, the effect is temporary and does not cause permanent damage.
The laser display industry joins other safety officials in urging the public to never aim a laser pointer at anyone's eyes or at the operator of a vehicle. At the same time, the public should understand that the threat pointers pose is primarily one of nuisance---they are a visual distraction and will not cause eye damage unless a person stares directly into the beam for an extended period.
FAA Studies Show No Injuries or Accidents
A recent Federal Aviation Administration analysis of 150 incidents involving lasers that illuminated aircraft found no cases of injuries or accidents. Although there have been anecdotal reports of permanent injuries suffered by pilots, there has never been a documented case supported by an ophthalmological examination.
Even under the worst of circumstances--involving lasers used in Las Vegas in the mid-1990s--officials never documented a single injury or accident caused by a laser display. The lasers on the Las Vegas strip were thousands of times more powerful than laser pointers and exposed pilots at low altitudes who were landing and departing from the nearby airport.
ILDA continues to study lasers and air safety and offers to work with safety authorities to further explore the issue and educate the public.