AW: [ RadSafe ] Hazardous Instruments Keep Pilots From Planes

[Kim Merritt]

Having a hazard distance of 6 miles is not hard to do with a 
laser.  Typical sources of laser illumination (at hazardous levels) could 
be laser light shows and research lasers, such as lidar.  When considering 
illumination of aircraft it is just as important to consider the 
non-injurious visual effects, such as startle, glare, flashblindness and 
afterimages.  These effect occur at lower thresholds than injury and can be 
just as dangerous (if the pilot can't see it is kind of hard to land the 
plane).  These visual effects are why there are reduced emission limits in 
the vicinity of airports.  6 miles from the airport would have put the 
plane in the Critical Flight Zone, which has a laser irradiance limit of 
50uW/cm2.  This is assuming that the exposure was to green light (which is 
what I think it was).  You can exceed the limit with FAA approval but have 
to have adequate safety measures in place to protect aircraft from being 
illuminated.

We routinely use lidar outdoors that have hazard distances in the 10's of 
km.  You just have to be careful where you point them and have adequate 
safety measures, such as radar interlocks.  I presented a paper on our 
outdoor laser safety program at the International Laser Safety Conference 
in March.  It is not included in the proceedings but I will try to upload 
it to my Laser Safety Forum web site this week 
<http://groups.yahoo.com/group/lasersafetyforum/>.

If you want to find out more about the requirements for conducting outdoor 
laser operations check out Chapter 29 of FAA Order 7400.2 
<http://www.faa.gov/atpubs/AIR/chapter_29.htm> or ANSI Z136.6.


At 04:45 PM 5/2/2005, you wrote:
>Can anybody tell me, what kind of lasers might be able to hit a pilots
>eye six miles out of the airport at 9 000 feet elevation to cause eye
>injuries?

Kim Merritt, CLSO
Radiation/Laser Safety Officer
Mainthia Technologies  MS 305
NASA Langley Research Center
Hampton, VA
(757)864-3210 office
(757)864-9449 fax
mailto:k.merritt at larc.nasa.gov