It’s long been taught that pointing lasers at people is dangerous, as they can potentially cause serious eye damage. It’s many times worse when lasers are aimed at aircraft, because the light can be very distracting, putting the lives of the crew and passengers at risk.
New information from the British Journal of Ophthalmology, however, shows that the pilots eyesight isn’t actually at risk at all in those types of situations.
Laser pointers, the common hand-held battery-powered devices, are designed to emit a very low powered beam that can highlight objects from across the room.
The small key chain sized devices are commonly used in conjunction with projected slide shows, or other similar demonstrations, or to tease and torment house pets. But when used irresponsibly, they can harm or endanger those they are aimed at.
For that reason, some countries have laws limiting the maximum power the lasers can emit. In the US, for example, the devices are limited to 5 mW. In the UK, however, there are no set laws limiting their power, but the UK’s Health Protection Agency does recommend that the laser pointers sold to the general public should not output more than 1 mW.
In both the US and UK there are laws prohibiting the act of pointing lasers at aircraft, and while it’s unlikely that these laws will change, there seems to be no evidence that the laser beams can actually cause eye damage at the distances involved. The low-powered beams lose so much of their energy traveling the distance between the device and the target, the danger has been eliminated.
In the research published by Prof. Marshall and his colleagues, it is shown that damage can only occur at short range. A laser beam shone from a much longer range is incapable of causing irreversible harm to a pilot’s eyesight, as it has to pass through thousands of meters of atmosphere, and the polycarbonate windshield, as well.
In fact, to date, there has only been one documented case of a pilot’s eyesight being permanently damage while in the air, which has been documented in the journal Aerospace Medicine and Human Performance. The pilot involved was flying at a very low altitude at the time of the injury, just under 400 meters in the air, much lower than standard cruising altitude.
However, Prof. Marshall and colleagues still stress the dangers of aiming lasers at aircraft, as the distraction they cause can lead to accidents in the air. Prof. Marshall added “In these situations, pilots tend to self-focus on a sudden bright light in the cockpit environment and may be dazzled resulting in an after-image and almost certainly will be distracted. Obviously, if such a distraction occurs at a critical time such as during landing then the result could be devastating.”