Advisory Circular Address Height And Markings Of Potential Hazards To Navigation

Among the FAA's main priorities is to keep all users of our national airspace safe. To maintain the safest aerospace system in the world, the agency must make sure the national airspace is navigable and free of obstructions.

When anyone proposes new construction or proposes to alter existing structures near airports or navigational aids, the FAA determines how the proposal would affect the airspace. These FAA determinations about the appropriate height of buildings, wind turbines and meteorological towers near airports, and how they are lighted and marked, contribute to the safe navigation of our skies.
 
The agency has updated its guidelines for the proper way to light and mark obstructions affecting navigable airspace. Advisory Circular 70/7460-1L for Obstruction Lighting and Marking is effective immediately. It cancels Advisory Circular 70/7460-1K, dated February 1, 2007.
 
The main changes to the updated advisory circular are as follows:

• Federal law requires that the FAA determine whether a structure that is proposed to be built or altered, 200 feet above ground level (AGL) or higher, or near an airport, does not pose a hazard to the airspace. To remain consistent with changes to the Code of Federal Regulation (CFR) Part 77, the height of a structure identified as an obstruction has been lowered from 500 feet (AGL) to 499 feet (AGL). All structures above 499 feet are considered obstructions and the FAA will continue to conduct an aeronautical study on these types of structures to determine their effect on the navigable airspace and ensure they do not create a hazard.
• New lighting is specified for wind turbines at various heights. These recommendations will provide needed guidance for the rapidly developing wind industry that takes into account the unique characteristics of wind turbine farms.
• The FAA implemented standards for voluntary marking of meteorological evaluation towers lower than 200 feet. This is an effort to make meteorological evaluation towers more noticeable and to add an extra layer of protection for low-level agricultural flight operations. These standards include those for lighting and marking of the tower and associated guy wires.
• New lighting and marking standards are provided to reduce the impact on migratory bird populations. This change will reduce the confusion and disruption to migratory bird patterns that has been attributed to certain obstruction marking schemes.
• A chapter on Aircraft Detection Lighting Systems (Chapter 14) was added to provide performance standards for these types of systems. This change is in response to community groups, industry, and the aviation community. New standards will enable lighting systems that operate based on aircraft proximity, increasing safety while reducing other impacts of the lighting schemes.

(Source: FAA news release)

FMI: www.faa.gov/regulations_policies/advisory_circulars