Unique control measures
Environmental
Trees
They are used a lot for termination. Check though if laser goes through, trees sway etc. Seasonal, leaf cover, wind affects. If you’re relying on them as a termination point then they need to be thick enough.
Water
Choppy water will reflect in lots of places. Reflection may be OK though as beam power falls by the time it reaches the water plus the distance back from the reflection?
Buildings
Metal edges, poles etc
Windows – you need control of the building to ensure it is empty. Maybe use a BAM (Beam attenuation area), but only if you’ve got assurances no-one in windowed areas (BAM would be a secondary protection)
Fairground rides
Often at events, will they be in the way?
Moving surfaces
Vehicles, automation, camera jibs
Movement of people
Terminating on hills – will people decide to go up there?
Terminating wall
In the USA where beam termination is often a strict requirement, they will often build a terminating wall for laser shows, or put a couple of trucks there to use the sides of.
Aviation
Height
3000 feet is usually top limit of concern when considering distance and beam diversion, below that you care.
If you are more than 5 nautical miles from an airport then you’re usually OK in that amateur planes don’t fly at night. Police or air ampulance helicopters may appear though.
Spotter
You need a spotter who’d visually monitor the termination area of the sky while the lasers are enabled.
Tools that can be useful
Flight radar
App that shows planes in the area, but beware it doesn’t cover Police, military
https://globe.adsbexchange.com/
Much more live than typical sites which often have a 5 min delay
You can set altitude so you can ignore commercial airliners (colour is altitude)
Striking an aircraft
If you strike a plane, you must report it. Where, who saw it, etc. Usually you are forgiven, no laser show company has yet been prosecuted.
Applying to aviation authorities
When applying to aviation authority you need:
- WSG coordinates (use google earth).
- Bearing of the display (you can overlay the site map on google earth to work it out). Typically you have a 60 degree angle from each side of stage. Give the two angles as the bearing extents.
- NOHD (Nominal Ocular Hazardous Distance) of your most powerful laser.
Notam – Notice To Air Missions
Notams apply in circles
For the hours you can just put from darkness to daytime, to give you all the time you might want.
UK
CAA – Civil aviation authority
Apply ideally 7 days before (can be less if you don’t have, often OK)
You can apply for multiple permits at once.
USA
USA has lots or airports, they are very all over this stuff.
Sometimes you have to have a termination wall built if you can’t comply with their airspace requirements.
FAA – Federal aviation authority (Federal, so regulatory body, required not guidance). 30 day notification period!
Western Australia
CASA
No NOTAM required, unless you’re really near an airport. They say its OK – just make sure you follow the best practce guidance.
