Outdoor Shows and the FAA
By Greg Makhov, Chair ILDA Safety Committee

If you use lasers in an outdoor environment in the U.S., and the laser beam enters navigable airspace, then you are required by federal law to report such activity and receive a letter from the Federal Aviation Administration that does not object to such activity.

There is a lot of technical jargon and some pretty complicated concepts in a report to FAA, but this information is necessary so that an FAA airspace specialist can evaluate the affect your operation will have on the surrounding airspace.  This report, “Notice of Proposed Outdoor Laser Operation(s),” has recently changed with the official adoption of the reporting form developed by the SAE G-10T laser hazards subcommittee.  This form is for all types of laser operations (such as research lasers), not just laser lightshows.

What’s the Concern? Visible lasers in excess of 5 milliwatts have the potential of causing eye injury, at ranges proportional to their power and divergence. The more power, or the lower the divergence, the greater the hazard range. However, beyond the range at which the laser beam can cause injury, the laser beam can create vision effects including afterimages, flashblindness, disorientation, and startle. These effects can occur at levels well below where any possible injury can happen. Hence the range for these non-injurious effects can be significant.

What do I need to know? The FAA form requires you to submit all relevant information about your laser operation.  This includes: 

•       Power, Wavelength, Divergence

•       Mode (CW, Pulsed), Pulse Width and Pulse Repetition Frequency

•       Location (Lat and Long, Degrees, Hours, Minutes, Seconds), Altitude

•       Point Direction(s), azimuth (compass direction), elevation (vertical angle)

•       Hazard Ranges (NOHD, SZED, CZED, LFZED)

•       Dates and Times of Operation

•       Map showing affected area

•       Control Measures

FAA will take this information and conduct an Aeronautical Study. This examines the volume and location of air traffic relative to the laser operation, and determines the degree of “intersection” between the laser operation and potential air traffic. Certain areas around airports, the so-called “Laser Free Zone” has such high volumes of air traffic that any laser operation will require significant and extensive means of preventing laser exposure of aircraft. There are several techniques to avoid aircraft exposure; collectively, these are known as “control measures”. One of the most common control measures is the use of Aircraft Spotters, who can detect the aircraft and shutter the beam before an exposure could occur.

Once FAA is satisfied that the laser operation will not adversely affect the airspace, and that the control measure(s) are adequate, they will issue a “Letter of Non-Objection” (FAA Terminology), and a NOTAM (Notice to Airmen), which informs all pilots and air traffic control facilities of the laser operation.

It is always the responsibility of the laser operator to terminate emission should aircraft approach the projection area. The NOTAM is not a restriction for airspace, it is simply a “heads up, there is a laser in this area”. It is always the job of the laser operator to protect the aircraft, even if it flies right into the middle of your show!

Control Measures: Almost any dangerous technology requires control measures. This allows you to work with or around it safely.  High tension lines are placed well above the ground as a control measure to prevent access to the electricity.

For laser shows, the most common control measure is the use of Safety Observers or Aircraft Spotters.  These people are trained in detecting aircraft around the show area, and can directly terminate the emission should one approach the projection zone. This is a serious duty, and training is required. The Spotter should know the laser show, and should know the air traffic pattern in the area.

However, Spotters are only effective for a distance of about 3 miles.  In some situations, one may be able to detect aircraft 10 or even 30 miles away, but this is not reliable (you can easily miss one that is only 5 miles away). So the power and divergence of the laser beam must be such that the hazard is contained within the range where the control measure (spotter) is adequate. Some scientific laser systems have enormous hazard ranges (can cause eye injury in orbit - no joke!), and aircraft spotters are not adequate.  In these cases, radar and infrared cameras are often employed as control measures. These are expensive and technically challenging solutions ($15K -$150K).

How do I learn all about this? The current standards for outdoor laser operations are the FAA 7400.2E, which is written primarily for FAA personnel, and the ANSI Z136.6, which is for laser operators.  Unless you have a strong background in laser safety and aviation matters, the Z136.6 is pretty technical. FAA's Advisory Circular 70-1 (caution: 22 mb PDF download) includes the actual forms used for reporting lasers used in airspace, and once again, is a very technical form.

Pangolin Laser System's website has extensive information about lasers in airspace intended for the general public.

Rockwell Laser Industries, the leading laser safety company in the U.S., offers a 3 day class “Safety of Lasers Outdoor” which covers everything from laser safety basics, to the theory behind outdoor hazard analysis, to actual FAA applications. For more details about this course, visit:   www.rli.com/training/indcal00.asp

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