This evening, our camera team coincidentially captured a laser attack hitting our Airbus A321 during its final approach into Cairo airport. Luckily nobody was hurt.
Under certain conditions, laser light or other bright lights (spotlights, searchlights) directed at aircraft can be a hazard. The most likely scenario is when a bright visible laser light causes distraction or temporary flash blindness to a pilot, during a critical phase of flight such as landing or takeoff. It is far less likely, though still possible, that a visible or invisible beam could cause permanent harm to a pilot's eyes. Although laser weapons are under development by the military, these are so specialized, expensive and controlled that it is improbable for non-military lasers to cause structural damage to an aircraft.
Aviation hazards from bright light can be minimized or eliminated in two primary ways. First, users on the ground can exercise caution, to prevent or minimize any laser or other bright light being directed in airspace and especially towards aircraft. Second, pilots should have awareness of laser/aviation hazards and knowledge of basic recovery procedures in case of laser or bright light exposure.
Pointing a laser at an aircraft can be hazardous to pilots and has resulted in arrests, trials and jail sentences. It also results in calls to license or ban laser pointers. Some jurisdictions such as New South Wales have restricted laser pointers as a result of multiple incidents.
There are many valid reasons that lasers are aimed into airspace. Lasers are used in industry and research, such as in atmospheric remote sensing, and as "guide stars" in adaptive optics astronomy. Lasers and searchlights are used in entertainment; for example, in outdoor shows such as the nightly IllumiNations show at Walt Disney World's Epcot. Laser pointers are used by the general public; sometimes they will be accidentally or deliberately aimed at or near aircraft. (Of course, no unauthorized person should deliberately aim any type of laser at or near an aircraft.)
Lasers are even used, or proposed for use, with aircraft. Pilots straying into unauthorized airspace over Washington, D.C. can be warned to turn back by shining eye-safe low-power red and green lasers at them. At least one system has been tested that would use lasers on final approach to help line up the pilot on the proper glideslope. NASA has tested a Helicopter Airborne Laser Positioning System. The FAA has tested laser-projected lines on airport runways, to increase visibility of "hold short" markings.
Because of these varied uses, it is not practical to ban lasers from airspace. This would unduly restrict legitimate uses, it would not prevent accidental illumination incidents, and it would not stop someone who deliberately, out of malice or ignorance, targeted aircraft. For this reason, practical laser/aviation safety is based on informed users and informed pilots.
There are some subjects which laser/aviation safety experts agree pose no real hazard. These include passenger exposure to laser light, pilot distraction during cruising or other non-critical phases of flight, and laser damage to the aircraft.
The main concerns of safety experts are almost exclusively focused on laser and bright light effects on pilots, especially when they are in a critical phase of flight: takeoff, approach, landing, and emergency maneuvers.
There are four primary areas of concern. The first three are "visual effects" that temporarily distract or block pilots' vision. These effects are only of concern when the laser emits visible light.
Distraction and startle. An unexpected laser or bright light could distract the pilot during a nighttime landing or takeoff. A pilot might not know what was happening at first. They may be worried that a brighter light or other threat would be coming. It is important that pilots be trained to understand the relatively minor impact of laser flashes caused by laser pointers and not to over react.
Glare and disruption. As the light brightness increases, it starts to interfere with vision. Veiling glare would make it difficult to see out the windscreen. Night vision starts to deteriorate. Laser light is highly directional so that pilots may act to exclude the source from their direct field of vision if properly trained. Remember also that pointer lasers have an illuminance of about 1 lumen/m2 whereas during the day the pilots have to deal with sunlight which is one hundred thousand times stronger.
Temporary flash blindness. This works exactly like a bright camera flash: there is no injury, but night vision is temporarily knocked out. There may be afterimages—again, exactly like a bright camera flash leaving temporary spots.