Laser control measures that prevent hazardous aircraft illuminations are designed to ensure aviation safety. An adequate aircraft protection system is necessary to receive a Letter of Non-Objection from the FAA. Historically, control measures have included the use of safety observers to monitor for aircraft and, in many applications, the use of safety observers is an effective control measure. In other situations, the use of alternate control measures may provide adequate safety and may be more cost effective.
For example, the use of safety observers can be expensive and, in remote and environmentally challenging locations, it can be difficult to find and retain enough qualified people willing to do this type of work. The cost for safety observers to support 140 full nights of laser operations per year at W. M. Keck Observatory on Mauna Kea, Hawaii is about $300,000, and the site is several miles away from cities and towns. With the addition of three other facilities on Mauna Kea that will routinely use lasers in their operations, the total cost for safety observers may be over $1,000,000/year and the number of safety observers needed may exceed the supply in the local population.
In addition to cost considerations, the effectiveness of safety observers in spotting aircraft is limited relative to the hazard distances of some lasers. To address the provision of safety at these distances, additional means to detect aircraft are needed to supplement or to replace the safety observer.
This document was revised from the 2011 version in response to feedback from the FAA. The revisions include edits to some performance criteria and clarifying the distinction between the requirements and examples of how systems can be implemented to meet them. A new example has also been added to the appendices.