What does a laser look like when it shines on pilots in an airplane cockpit?
The 14-second-long animation contains photos taken in a professional flight simulator during scientific studies.
It shows the three visual effects of startle and distraction (dimmest flash), glare (brighter, making it hard to see out the cockpit) and temporary flashblindness (loss of vision until the afterimage fades).
This animation is probably the most realistic way to understand what a laser exposure looks like. A still photo implies that the laser is always on the aircraft.
But in real life, the laser flashes -- it is impossible to keep a hand-held beam fixed on a moving plane.
Pilots generally experience one or more flashes as the beam sometimes hits, and mostly misses, the cockpit.
How the flash time was determinedA typical flash from a hand-held laser at 1000 feet lasts about 1/50 of a second. In the FAA simulator studies, the flash used was one second long.
The animation above "splits the difference" by using 1/2 second flashes. We feel this is a realistic portrayal of how long a typical exposure might last.In addition, there is a 2-1/2 second fade-out after the brightest exposure. This demonstrates how an afterimage fades.
To keep the file size down and the animation short, the fading was made faster than normal. In real life, it will take longer to fade and much longer for night vision to recover.
If the light was a laser pointer, how close is it?In the animation, the power levels are known. From this, we can compute distances if the light was from a legal (5 mW) laser pointer.
The dimmest level corresponds to a legal laser pointer 3,700 feet away, the medium level is a pointer about 1,200 feet away, and the brightest level is a pointer just 350 feet away.The diagram at right shows this more clearly. The diagram includes FAA-determined safety distances for flashblindness, glare and distraction.
You can see where the simulator photos fall, on this distance scale.
Details about the photos which make up the animation
The graphic below explains details the various power levels, and the visual levels to which they correspond. As you read about the various levels, you may also want to reference the diagram above, as well as this table which shows distances for a laser pointer to reach various safety zones.
Tuesday, January 25, 2011
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