Research shows laser eye damage possible at extended ranges
By Tammy Chatman, Flight For Life
A Coast Guard helicopter crew member suffered eye damage when he was stuck by green laser lights while training in Coast Guard Air Station/Sector Field Office Port Angeles, in Washington State, on March 21, 2018.
He and two other members of the MH-65 Dolphin helicopter crew landed safely after being hit by a laser several times that evening.
The aircrew was immediately examined by the duty corpsman. After consultation with the flight surgeon, two of the three aircrew members were medically grounded until they were seen by an optometrist.
One of the crew members was found to have suffered eye damage and was grounded for seven days. The other crew member was grounded for two hours but has since returned to duty.
Because members of the crew were medically grounded, Naval Air Station Whidbey Island and Sector Columbia River in Warrenton, Ore., became responsible for covering the Port Angeles station’s area of until Port Angeles aircrews were medically cleared. This of course created a delay for any emergent situations due to the distance the backup teams had to travel.
In 2017, there were 6,753 laser strikes of aircraft reported to the FAA. This compares with 7,442 reports in 2016 and 7,703 reports in 2015. This is a 9% drop compared with 2016, and a 12% drop compared with 2015. It is believed that the reduction in numbers is due to the lack of reporting those strikes that are not considered by the pilot to be serious or caused any issues. As of July 1 2017, there have been over 55,000 laser strikes reported in five countries (U.S., Canada, U.K., Australia, and Italy) since 2004. (Insert 1.)
The primary safety concern with lasers is that they can cause “visual interference” with pilot performance during critical phases of flight. There are three main visual interference hazards: 1) temporary flash-blindness, 2) glare and disruption, and 3) distraction.
- Temporary flash-blindness. Think of a camera flash directly in your eyes — the pilot is temporarily unable to see until the afterimage fades.
- Glare and disruption. The pilot cannot see past the light glare, until the light stops. The glare is bright enough to disrupt normal operations.
- Distraction. The pilot is distracted by steady or flashing laser light that is significantly brighter than other nighttime sources such as city lights and airport marker lights. While not technically a “visual” interference — the pilot can see despite the light — the light distraction can interfere with mental awareness. Education and training in laser hazards and how to react to them can help to overcome this.
Visual interference is most hazardous during critical phases of flight -- landings, takeoffs and emergency maneuvers. If illumination occurs at cruising altitude, there is usually plenty of time and altitude to recover even from flash-blindness.
When a pilot is flash-blinded on final approach, the situation can be very dangerous. This is especially hazardous because even a low-powered “legal” laser pointer can be a distraction at a distance of two miles with more powerful lasers being of even greater concern.
When a pilot is being targeted they may also be worried about eye damage and eye injuries, and the possibility that the laser is on a weapon. A worried pilot is a distracted pilot -- not a good thing during critical flight phases such as landings, takeoffs and emergency maneuvers.
In the United States, laser pointers cannot exceed 5 mW. The diagram below shows the hazard distances for a 5 milliwatt legal green laser pointer with a 1 milliradian beam divergence:
- It is a potential eye hazard from the pointer to about 52 feet.
- It is a temporary flash-blindness hazard from the pointer, out to about 260 feet. On the diagram, this is illustrated in the inset photo “Near flash-blindness” which shows what a 5 mW laser looks like at 350 feet.
- It is causes glare and is a disruption hazard from about 260 feet to about 1,200 feet. This is shown in the “Glare” inset photo where the runway is not visible.
- It is a distraction hazard from the pointer to over two miles (11,700 feet). The distraction can be dangerous during a critical phase of flight, such as takeoffs and landings. Note that this is not truly “visual” interference, since a pilot can see despite the light. Instead, it is a mental distraction, interfering with the pilot’s attention. This can be overcome if a pilot is aware of laser hazards, and how to react to them (e.g., ignoring low-level laser distractions).
The laser’s light is not truly safe until it is indistinguishable from background lights on the ground. A pilot may notice a flashing dot of light, but it should not be enough to cause a distraction. Keep in mind that there is absolutely no reason to aim a laser at an aircraft except in an emergency situation such as a wilderness rescue.
Why is a laser pointer hazardous to aircraft?
We see three statements constantly repeated on Internet message boards and on comments to news stories about incidents. People write (inaccurately) that 1) the dot from a laser pointer is small, 2) that it is hard to hit or keep it on an aircraft, and 3) that an aircraft's windows are facing up and thus away from the ground. While there is some truth in these statements, the fact is that laser light can all too easily be a distraction or obstruction to pilot vision:
- Beam size: A laser's beam spreads out. At long ranges the beam can be many inches or even feet in diameter. When laser light hits an aircraft's windscreen, tiny scratches and dirt spread the light out even more, causing glare around the beam center. The result is that pilots do not see a small dot, they see a large glow similar to being in a flashlight or searchlight beam. It can be difficult or impossible to see through the glow.
- Beam flashes: Yes, it is hard to hand-hold a laser on a moving target that is far away. That's why in most laser pointer incidents, pilots don't see a steady light on them. Instead, they see one or more flashes. The flashes are distracting at best, and at worse, they can be bright enough to cause temporary flash-blindness. This is similar to having a camera flash (or flashes) goes off in your face. Even if the beam is just waved around the aircraft so it does not directly enter the windscreen, it can be distracting or worrisome to see a waving beam aimed towards one's aircraft.
- Window orientation: If a pilot can see the ground outside his or her window, then obviously the pilot could be directly hit by a laser aimed from anywhere within that view. Plus, even if the pilot's eyes are not in a direct line with the laser source, the laser beam could light up other areas in the cockpit such as the ceiling, causing a distraction. This is because, as discussed above, the light at altitude creates a large glow on the windscreen.
How can we reduce laser incidents? See the graphic below.
So, when thinking about risks from laser light, don't think just about airplanes flying at 35,000 feet. Think about the times airplanes are at most risk: during takeoffs and especially during landings. Then there are helicopters, which fly low and slow and have large bubble canopies. That's why almost all laser pointer aircraft incidents involve airplane landings, takeoffs, and helicopter operations.
Information from www.laserpointersafety.com