FAA Efforts to Update Science Used to Evaluate Aircraft Noise

On May 7, 2015, the Federal Aviation Administration (FAA) announced it would begin evaluating its methods for measuring aircraft noise. For decades federal regulations prescribed a process under 14 CFR Part 150 for calculating aircraft noise impacts using the Day-Night Average Sound Level (DNL) metric. In the early 1980s the FAA established 65 dB DNL as the threshold at which federal funding could be available to homeowners for soundproofing or other mitigation.

The DNL metric is an average of all aircraft noise during a 24-hour period, with a 10-decibel (dB) penalty (increase) for each aircraft operation occurring between 10 p.m. and 7 a.m. This penalty accounts for the higher human sensitivity to noise during the nighttime hours.

The Metropolitan Airports Commission (MAC) assesses aircraft noise impacts, for each of its airports, using DNL noise contours and as part of the long term comprehensive planning process. An annual noise contour analysis is also conducted for the Minneapolis-St. Paul International Airport (MSP). Communities across the nation, including communities represented on the MSP Noise Oversight Committee, have requested the FAA consider other federally-accepted metrics to express and represent the effects of aircraft noise exposure.

In its news release, the FAA said its evaluation will be a multi-year process and will begin with a survey of public perceptions of aircraft noise. The survey is set to begin within the next three months and will take place for a year’s time in communities situated around 20 airports nationwide. The FAA is not disclosing the airport communities in which it will conduct the survey.

According to the FAA, the results will be used to determine whether an update to FAA policies regarding the DNL metric is warranted, along with the parameters under which a home is eligible to receive federal funding for mitigation.

Read more about the FAA's announcement here: FAA Press Release May 7, 2015