In February 2011, the National Park Service (NPS) released the Draft Environmental Impact Statement (EIS), Special Flight Rules Area in the Vicinity of Grand Canyon National Park. It was developed to support the mandate of the 1987 National Parks Overflights Act, namely to address the substantial restoration of natural quiet and to reduce the impact of aircraft noise on park resources and visitors' experience in the vicinity of Grand Canyon National Park.
Substantial restoration of natural quiet in Grand Canyon National Park is achieved when reduction of noise due to aircraft operations at or below 17,999 feet mean sea level (MSL) results in 50% or more of the park area achieving natural quiet (i.e., no aircraft audible) for 75% to 100% of each and every day.
The Environmental Measurement and Modeling Division at the Volpe Center—a part of the U.S. Department of Transportation's Research and Innovative Technology Administration (RITA—supported the Draft EIS with a comprehensive noise analysis of four alternatives: Alternative A, continued current management (the No Action Alternative), and three action alternatives—including the NPS Preferred Alternative. The noise analysis was performed using the Federal Aviation Administration's (FAA) Integrated Noise Model (INM) version 6.2a. This is the model that was recommended by the Federal Interagency Committee on Aviation Noise (FICAN) as the best practice modeling methodology currently available for evaluating aircraft noise in national parks, and agreed to by NPS and FAA after extensive studies comparing the models currently available and upgrades to the previous version of INM. The Volpe Center team continues to support the FAA and NPS efforts to preserve environmental quality at national parks across the nation.
