U.S. Department of Transportation
Federal Aviation Administration


Subject: Approval of Mitigation Measures in a Part 150 Program That Cover Areas Below The DNL 65 dB

Date: July 25, 1995

From: Manager, Community and Environmental Needs Division, APP-600

Reply to Attn of:  VCatlett
(202) 267-8770
FAX: (202) 267-5257

To:  All Regions and AMA-620
Attn: Manager, Airports Division

The misconception has become more prevalent recently that the FAA cannot approve mitigation measures in a Part 150 program that go below the DNL 65 dB noise contour.  This is not the current FAA policy, as explained in the January 1989 Report to Congress "Eligibility of Noise Abatement Proposals for Grants-in-Aid Under the Airport Improvement Program," and subsequently addressed in a change to Order 5100.38, paragraph 710.

If the following three criteria are met, mitigation below the Federal standards depicted in Table 1 of FAR Part 150 may be approved.

The airport operator adopts in the Part 150 program a designation of non-compatibility different from the table in Part 150 (local land use deviation, as provided for in Part 150, Table 1).

The NEM contours and NEM and NCP narrative identify the area as noncompatible and propose to mitigate in that area.

The airport operator proposal to mitigate otherwise meets the FAR Part 150 standard to reduce or prevent noncompatible land uses  (e.g., sound proofing to appropriate NLR reduction levels, avigation easements to prevent noncompatible development, etc.).

If the airport operator's recommendation meets these tests, language that would exclude the measure from Federal funding eligibility is not appropriate in the ROA.  Although at this time it is not likely that measures below the DNL 65 will get noise set-aside funding due to the priority of areas of higher noise impact, the airport operator may opt to use entitlement monies or may opt to apply for passenger facility charges.  Also, with the completion of the federal phase out of Stage 2 aircraft greater than 75,000 pounds by the year 2000, Federal funding to mitigate below the DNL 65 dB will be more viable.

This guidance has been coordinated with the Policy and Regulatory Division of the Office of Environment and Energy (AE-300), the Program Guidance Branch (APF-510) and the Passenger Facility Charge Branch (APF-530).  Please distribute to regional and ADO personnel who are responsible for providing noise mitigation guidance.

Lynne S. Pickard