ATNS is a computer program that assists in determining whether a change in air traffic procedure -- for airport arrivals and departures between 3,000 and 10,000 feet AGL -- will generate a 5 dB(A) increase in noise to underlying communities and therefore is likely to be controversial.
ATNS is a computerized version of the former FAA Notice N 7210.360, "Noise Screening Procedure for Certain Air Traffic Actions Above 3,000 Feet AGL." This notice provides guidance to air traffic managers in identifying air traffic changes that will increase aircraft noise exposure, and the possible need for an environmental assessment (EA) as required by FAA Order 1050.1, "Policies and Procedures for Considering Environmental Impacts."
Although air traffic changes above 3,000 feet above ground level (AGL) are categorically excluded from further environmental documentation under Order 1050.1, new noise introduced over noise-sensitive areas may be a highly controversial public issue. In such instances the exclusion does not apply and the action should be the subject of a determination of extraordinary circumstances in accordance with Order 1050.1.
The ATNS evaluates the potential noise impacts resulting from changes in airport arrivals and departures by screening proposed changes to determine whether new or increased noise is likely to exceed permissible levels over communities beneath the aircraft route. The model guides the user step-by-step through the noise screening procedure, performs the calculations, and prepares written documentation on the findings. Some preparation by the user is required, however, to compile information about the proposed change and the communities that may be affected by it.
The checklist in the former FAA Notice N 7210.360 was first converted to a computerized model in 1995 as ATNS 1.0. Version 2.0 of the ATNS software and its users manual (FAA-AEE-99-01) replace the previous software and manual.