Directed bright light sources projected near airports or into any airspace can create potential flight control disruptions and/or eye injury to pilots, crew members, and passengers of aircraft. The number of laser illuminations of aircraft has significantly increased during the past few years. In particular, the reporting of laser incidents involving law enforcement helicopters has substantially increased.
Trinidad and Tobago have both recorded numerous instances of laser exposures that have been disruptive to flight operations. The effects of these occurrences to flight crews have ranged from startle to glare and, in some instances, flash-blindness and afterimage.
Directed bright light sources, particularly laser beams, projected near airports or into any airspace can cause two flight safety concerns:
1. The primary concern is when non-injurious, bright levels of directed light unexpectedly enter the cockpit. Depending on the brightness level, the light could startle the pilot(s); could cause glare, making it difficult to see out the windshield; or could even create temporary vision impairment (flash-blindness and/or afterimage). The illumination and glare may be short — one or a few bright flashes — but the startle and afterimage effects could persist for many seconds or even minutes.
2. A secondary concern is if a laser beam is so powerful that it causes temporary or permanent eye injury to anyone (pilot, crew members, passengers) viewing it. Fortunately, this is only a remote possibility because the laser power required to cause eye injury to a pilot in flight greatly exceeds that of lasers in common use today.
Therefore, the most likely in-flight safety hazard is that of a bright non-injurious flash causing disruption in the cockpit workflow. Such effects pose significant flight safety hazards when the cockpit workload increases below 10,000 ft. above ground level (AGL), in critical phases of flight (approach and landing), dense traffic areas (terminal environment and en-route areas), and in proximity to airports. This safety hazard is applicable to both single and dual aircraft cockpit operations.
Even laser pointers can cause adverse effects that could cause pilots to be distracted from their immediate tasks. Exposures to pilots from persons using laser pointers have been reported in increasing numbers, particularly against law enforcement helicopters.
The red laser pointers commonly seen in classrooms and conference venues are low-powered devices of less than one milliwatt (mW), emitting light in the wavelength range of 630 to 670 nanometres (nm, or 10-9 m). These are normally ‘Class 2’ laser devices (the higher the class number, the greater the hazard), with insufficient power to cause actual physical harm, although they still require care in operation.
Green pointers are readily available with a maximum power rating of 5 mW, and these are classified ‘3R’ (more hazardous that Class 2). They emit light at a wavelength of 532 nm, perceived by the human eye as green. The eye’s maximum sensitivity to visible light is around this wavelength, and the eye will interpret a green laser light of a given power as being up to 30 times brighter than a red laser of the same power.
Direct eye exposure to one of these laser beams can result in momentary ‘flash blindness’ with possible after-images, the duration of which will vary with the relative brightness. As all of the incidents occurred at night, the pilots’ eyes would have been at least partially dark-adapted and thus more susceptible to dazzling. The human eye has a natural blinking reflex that activates after about 0.25 seconds’ exposure, limiting the amount of light reaching the retina.
Nonetheless, the dazzling effect on the eye can be a major distraction, particularly in situations of high workload. Some of the reported incidents took place immediately after take-off, and probably before the crew had fully transitioned onto instruments.
To inflict actual eye damage with a 5 mW green laser pointer would require some effort, as both the low power and the eye’s natural defence would combine to limit potential damage. So, one would think, these devices can be written off as little more than a nuisance.
Not so. Some vendors advertise higher-powered (from 10 to 400 mW) green laser pointers – these are definitely harmful, and can cause permanent eye damage. Price may put these out of the reach of normal users, but not necessarily for someone with malicious intentions.
A laser illumination event can result in temporary vision loss associated with:
1. Flash blindness (a visual interference that persists after the source of illumination has been removed)
2. After-image (a transient image left in the visual field after exposure to a bright light)
3. Glare ( obscuration of an object in a person’s field of vision due to a bright light source located near the same line of sight).
Laser effects on pilots occur in four stages of increasing seriousness –
Given the many incidents of cockpit illuminations by lasers, the potential for an accident definitely exists but the fact that there have been no laser-related accidents to date indicates that the hazard can be successfully managed. Technologies are available to mitigate the effects of lasers, but are cumbersome, do not provide full-spectrum protection, and are unlikely to be installed on airline flight decks in the foreseeable future.
Laser Pointer Precautions
- Never aim a laser pointer at persons, vehicles or aircraft, no matter how far away they are.
- Keep these devices out of the reach of children.
- Never look directly into a laser beam, especially not through an optical instrument such as binoculars.
- Do not aim a laser beam at a mirror or similar surface.
- Do not use a pointer that lacks warning and/or explanatory labels.
- If you know somebody with a green ‘astronomy’ type pointer, caution them specifically against targeting aircraft.
The use of Laser Lights is a PROHIBITED ACTION under LEGAL NOTICE NO. 145
REPUBLIC OF TRINIDAD AND TOBAGO
THE CIVIL AVIATION ACT, CHAP. 49:03 REGULATIONS
THE CIVIL AVIATION [(NO. 8) AVIATION SECURITY] (AMENDMENT) REGULATIONS, 2011 states:
3A. (1) Notwithstanding the requirements of regulation 3, a person shall not recklessly or negligently perform any act, whether on board an aircraft or outside an aircraft, that is likely to endanger or endangers an aircraft or a person on board an aircraft.
(2) An act under sub regulation (1) that is likely to endanger or endangers an aircraft or a person on board an aircraft, includes but is not limited to the following:
(a) a radio transmission that affects a communication, navigation or automatic flight guidance systems of an aircraft; and
(b) a laser light source, fireworks, flares or other light sources directed at an aircraft that may affect a flight crew member in the performance of his duties.
(3) A person who contravenes sub-regulation (2) commits an offence and shall be liable on summary conviction to a fine of ten thousand dollars and to imprisonment of one year.