More changes for ‘natural quiet’ rule

 - May 2, 2008, 7:09 AM

The subject of aircraft noise in the Grand Canyon area has been of special interest to helicopter operators for years now, but it might be taking on an even broader dimension. The definition of “substantial restoration of natural quiet” might lead to new rules for aircraft flying over the Grand Canyon National Park at and above 18,000 feet, according to a public notice from the National Park Service (NPS).

In the public notice in the Federal Register, the NPS said that given the volume of high-altitude commercial jet and general aviation traffic overflying the Grand Canyon above 17,999 feet msl and a recent court decision, the “substantial restoration of natural quiet” at Grand Canyon National Park as currently defined cannot be attained.

The NPS is proposing that substantial restoration of natural quiet will be achieved when the reduction of noise from aircraft operations at or below 17,999 feet msl results in 50 percent or more of the park achieving restoration of the natural quiet (no aircraft audible) for 75 percent to 100 percent of the day, every day. NPS said that 50 percent of the park is a minimum in the restoration goal.

“This clarification of the restoration definition, while focusing on air-tour and air-tour-related and general aviation aircraft that are conducting overflights of GCNP
at altitudes at or below 17,999 [feet] msl, also incorporates measures to address noise from all aircraft,” the notice said.

The GCNP and the FAA are currently preparing an environmental impact statement. GCNP, in consultation with the FAA, has determined in the noise methodology section of the EIS that aviation noise above 17,999 feet msl will be considered as a cumulative impact for purposes of the EIS, and aircraft noise generated at or below 17,999 feet msl, within the Special Flight Rules Area, will be managed to attain the NPS recommendations and meet restoration management objectives consistent with GCNP management direction, 2006 NPS Management Policies and a 1995 Report to Congress.

“The NPS recognizes that due to the impact of aviation noise on park resources and visitor experience, even with implementation of quiet technology aircraft, restoration of the natural quiet as defined in the 1995 Report to Congress will not be achieved without reduction of the sounds produced by jet traffic above 17,999 [feet msl],” the NPS notice said.

The NPS is accepting comments on the clarification until May 9.