NIRS Screening Tool (NST) Version 6.1
The NIRS Screening Tool (NST) is an application designed to provide guidance in evaluating potential noise impacts as a result of changes in airport arrivals and departures above 3,000 feet above ground level (AGL). This is accomplished by screening the proposed changes to determine whether there is the potential to increase noise levels over communities beneath the aircraft route.
Background
Although change actions above 3,000 feet AGL are categorically excluded from
FAA Order 1050.1E, Environmental Impacts: Policies and Procedures, new noise
introduced over noise sensitive areas has the potential to be highly controversial
on environmental grounds. In these instances, the exclusion does not apply
and the action should be the subject of a determination of extraordinary
circumstances in accordance with Order 1050.1E and an environmental assessment
(EA) must be prepared
In order to assist with this process FAA issued Notice N7210.360, Noise Screening Procedure for Certain Air Traffic Actions Above 3,000 Feet AGL, on September 14, 1990. This notice contained a series of decision tables that airspace planners could consult to determine the potential impact of a proposed change.
In August 1995 the decision tables from Notice N7210.360 were automated in the release of the Air Traffic Noise Screening Model (ATNS) Version 1.0. The ATNS was designed to analyze a single route change at a time. It was not designed to analyze the effects of large-scale airspace changes.
In July 1998, FAA released the Noise Integrated Routing System (NIRS) Version 1.0. NIRS was designed to analyze the effects of large-scale airspace changes over a broad area. It has the ability to assess multiple airports, and thousands of tracks and operations.
The NIRS Screening Tool (NST) is a revision and update of the ATNS. It encompasses the ease-of-use of the ATNS with the noise computing capabilities of NIRS.
Application
NST applies only to simple air traffic changes affecting aircraft actions above
3,000 feet AGL over noise sensitive areas. It is applicable for changes involving
aircraft route, aircraft altitude, aircraft mix, number of operations, time
of day, or even operational procedures. If a change action involves aircraft
departing at altitudes above 10,000 feet AGL, or arriving above 7,000 feet
AGL, a noise screen is not needed. (Note: However, if the change is above
a national park or wilderness area, it is recommended that screening be conducted
up to 18,000 feet AGL.) See ATA-300 memo dated September 15, 2003, for more
information.
The NST guides the user step-by-step through the noise screening procedure, performs the calculations, and prepares the report on the findings. Some preparation by the user is required to compile information about the proposed change and the communities that may be affected by it.
Screening Criteria
To determine the possibility for impact, the NST
allows the user to compare a baseline and an alternative scenario. For each
scenario, all population in the study area is divided into three categories:
(1) those receiving an increase in noise exposure relative to the baseline,
(2) those receiving a decrease, and (3) those having no change. The rules defining
the increase, decrease, and no-change categories and the sources for each rule
are given in the following table.
NIRS Screening Chart
These criteria have been established in accordance with FAA Order 1050.1E, the Federal Interagency Committee on Noise (FICON), and the Final EIS for the Expanded East Coast Plan.
Availability
NST is currently available for use only by FAA employees. Persons in FAA service
areas or facilities may contact the Environmental Programs Group for information.
