Part 161, “Notice and Approval of Airport Noise and Access Restrictions,� is formally codified under Title 14 of the U.S. Code of Federal Regulations (14 C.F.R. Part 161). It defines complex processes for airports to follow when considering the adoption of noise or access restrictions that directly or indirectly affect the number or hours of Stage 2 or 3 operations.

Airport owners must examine the effects of any proposed restriction within an “airport noise study area.� That includes at least all property within the 65 decibel (dB) Day-Night Average Sound Level (DNL) contour, which is equivalent to the 65 dB Community Noise Equivalent Level (CNEL) contour used in California. (These metrics are described in greater detail here.)

Part 161 directs airports to follow Part 150 methodologies for measurement, modeling, and description of noise, and for determining whether land uses are compatible with a given noise exposure level. The FAA has stated that the Part 150 procedures give airport owners flexibility but also help ensure a uniform national standard for measuring airport noise impacts. Part 150 supplies guidelines regarding noise levels (measured using DNL or CNEL) that are generally considered compatible with specified land uses. LAWA adopted the Part 150 guidelines when conducting the VNY Part 150 study.

The FAA adopted a broad definition of the term “noise or access restriction,� to include any restriction – including airport lease provisions – that affects the operation of aircraft and has the effect of controlling noise. A “noise or access restriction� does not include, however, noise abatement operational procedures (such as displaced thresholds, preferential runway systems, noise abatement flight tracks and the like) because they are not expected to limit the total number or hours of aircraft operations.

It also should be noted that Part 161 does not apply to Stage 2 restrictions proposed before October 2, 1990, Stage 3 restrictions that became effective before that date, or to a number of exempted situations. These so-called “grandfathered� conditions are significant at VNY, because LAWA is pursuing a phase out of noisier aircraft that it proposed in June, 1990. That parallel effort is described in greater detail here.

The rules under consideration at VNY largely involve restrictions on Stage 2 operations, although it is possible that some Stage 3 operations will be affected. Different requirements apply to restrictions affecting Stage 2 and 3 aircraft.

An airport proprietor can restrict Stage 2 operations without FAA approval so long as it analyzes the effects of the proposal and publishes notice of the restriction.

Airport proprietors are required to publish notice of a proposed restriction in a general circulation newspaper and certain parties must be notified directly. The FAA also will publish the notice in the Federal Register. The notice must

• describe the proposed restriction
• discuss the specific need for, and purpose of, the restriction
• identify the aircraft operators and types of aircraft to be affected
• set forth the proposed effective date of the restriction and the method of implementation
• analyze the proposed restriction
• invite public comment

The most important requirement with respect to Stage 2 restrictions is the preparation of analysis on the costs and benefits of the proposed restriction, that includes:

• an analysis of the anticipated or actual costs and benefits of the proposed restriction
• a description of alternative restrictions which were considered
• a description of the alternative measures considered that do not involve aircraft restrictions
• a comparison of the costs and benefits of the restrictive and non-restrictive alternatives

Although it will not review or approve local Stage 2 restrictions, the FAA has indicated its view that the analytical requirements are intended to be similar for Stage 2 or Stage 3 restrictions. The regulations recommend that airport proprietors prepare the same analysis for Stage 2 as for Stage 3 restrictions.

Part 161 imposes more substantial impediments to Stage 3 restrictions. The process has three principal elements:

• analysis to justify the restriction and explain its environmental and economic impact
• notifying the public and allowing time for comment on the proposed restriction
• submission of the restriction for FAA review and approval

Unlike Stage 2 restrictions, an airport must demonstrate that the benefits of a proposed Stage 3 restriction has a reasonable chance to exceed the costs, and evidence that:

• the proposed restriction is reasonable, nonarbitrary, and nondiscriminatory
• the proposed restriction would not unduly burden interstate or foreign commerce
• the proposed restriction would maintain safe and efficient use of navigable airspace
• the proposed restriction would not conflict with any existing federal statute or regulation
• the applicant has provided adequate opportunity for public comment
• the proposed restriction does not create an undue burden on the national aviation system

The requirement that FAA must review and approve a Stage 3 restriction increases the agency’s role significantly above review of procedural requirements.

The full Part 161 regulation may be reviewed here.