SAE standard provides illumination on laser danger

  • 13-Nov-2010 06:39 EST

A laser illumination in the cockpit “is like a flash bulb going off in front of your face,” said retired pilot and SAE Committee Vice Chairman Bill Connor.

SAE Aerospace Recommended Practice (ARP) 5598 that addresses pilot vision problems caused by ground based lasers is in widespread circulation around the globe, according to one of its main authors. The “living document” has been well received by the FAA and by the International Federation of Airline Pilot Associations, which is distributing it around the world, said Bill Connor, Ph.D., a retired airline pilot who has been studying the issue of cockpit laser illuminations for many years.

Captain Connor is Vice Chairman of SAE International’s G-10 Committee and Chairman of the G-10T Laser Operational Safety Hazards Subcommittee that was responsible for developing ARP 5598, Unauthorized Laser Illuminations: Pilot Operational Procedures. The subcommittee was formed in 1994 in response to a request from then-FAA Administrator David Henson.

ARP 5598 offers a brief overview of the flight hazards associated with laser exposures and identifies areas requiring research necessary to fully understand their effects on pilot performance. It also introduces recommended practices to pilots who encounter lasers during flight operations to mitigate effects on the eyes.

Depending on the intensity of the light, the proximity to the laser, and where the laser appears in the pilot’s field of view, there is a range of visual effects that pilots can experience. Starting at the least offensive effect, laser brightness can cause startle and distraction. This can be a serious matter during a critical phase of flight, such as approach and landing. As the relative brightness increases, pilots can experience glare, which can prevent them from seeing outside references (e.g., terrain or runway references) or their own cockpit instruments. Facing even brighter light, pilots can experience flash blindness, which can persist for a few seconds to a few minutes. If the intensity of the light is greater, the pilot may also experience after-images—bright spots than can last in the pilot’s field of view for several minutes. If the irradiance is strong enough, physical damage to the eye, such as retinal burns, can occur.

Cockpit laser illuminations can cause pilot flash blindness effects for more than a minute, according to Connor, who has been illuminated several times. “It’s like a flash bulb going off in front of your face,” he said.

Loss of sight, orientation, and equilibrium obviously pose problems, even at altitude. “But when you’re at 1500 feet and coming down at 160 knots, the last thing you want to do is lose your vision, especially when you don’t know when you’re going to get it back,” Connor said.

According to ARP 5598, a marked increase in the number of laser illumination incidents across the U.S. began in the summer of 2004. The increase coincided with lasers becoming cheaper, more compact, and more powerful. Green laser pointers are now available for very low cost (under $100) and are already in the hands of thousands of consumers unaware of the associated safety risks to flight operations in navigable airspace. The possibility of retinal damage is low from the lasers used in typical illuminations, but startle, distraction, and disorientation are still major concerns.

Evidence from U.S. military studies suggests that the startle response to eye-safe laser irradiance levels can be minimized in pilots who undergo specialized procedural training for recognition and response to laser exposures.

ARP 5598 notes that currently some airlines have prepared procedures to deal with laser illumination events. But there are no abnormal or emergency procedures developed for the industry as a whole. These procedures should address the human factors issues associated with flight crewmember verification of flight display instruments during visual impairments and maintaining control of the aircraft, according to ARP 5598.

Flight crewmembers should be familiar with the characteristics of a laser illumination and its symptoms when one member of the flight crew has been exposed. The affected crewmember should communicate immediately as to his or her visual status and transfer control to the pilot that has not been affected. Communication procedures for the flight deck should be developed to determine transfer of control protocol.

One of the other many recommendations of ARP 5598 is an education campaign for the general public about the dangers of lasers. Captain Connor himself has spoken on the issues at many venues. In addition to discussing ARP 5598, he shows an educational video titled "Aircraft Laser Illumination Awareness for the Aviation Community," developed by Dr. Leon McLin, Air Force Research Laboratory, and sponsored by the FAA, the U.S. Department of Defense, and other entities, which is part of the ARP 5598 document development. The video is available for interested parties.

“Work continues among many entities to limit the dangers of laser illumination,” Connor said. McLin continues research on laser eye protection to determine visual interference with information transfer filtering during critical phases of flight. This research may become an update or extension of ARP 5598.

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