What can the airport do to restrict noisy planes?

Federal Law prohibits new local new noise abatement restrictions without first conducting a cost-benefit analysis following the F.A.R. Part 161 requirements. Noise regulations enacted prior to 1991 are "grandfathered" and are allowed to remain in place. The 14 CFR Part 161 process requires airports to demonstrate how many residential or other incompatible uses will no longer be included inside the 65 DNL noise contour boundaries by enacting the new noise regulation. Most noise complaints originate in areas far outside the 65 DNL noise contour lines due to the low ambient noise level.