The FAA has issued a final rule establishing a class of “quiet technology” aircraft to fly commercial tours over Grand Canyon National Park (GCNP). The rule requires no action by commercial air-tour operators; it simply identifies specific aircraft that qualify for the GCNP quiet-aircraft-technology designation. The FAA has called the rule a first step toward possible new or modified, less restrictive Grand Canyon tour flight corridors reserved for quiet-technology aircraft.

The amendment to FAR Part 93 covers only Grand Canyon commercial air-tour aircraft, thus the designation “GCNP quiet aircraft technology.” At least for now, it will not affect aerial-tour operators at other U.S. national parks. It does not relieve Grand Canyon tour operators of any current operational limitations under the Special Flight Rules governing Canyon airspace.

The ‘Quiet Aircraft’ Designation

Noise levels used to determine which models rate quiet technology designation are based upon a noise-per-passenger seat formula under which “larger aircraft with more passenger seats are allowed to generate more noise per aircraft, but less noise per passenger.”

The FAA determined that the de Havilland Canada Twin Otter Vistaliner conversion, Eurocopter EC 130 and MD 600 and MD 900 helicopters all merit the GCNP quiet-aircraft-technology designation. The Cessna 182 and 207, Eurocopter AS 350, Bell 206B and 206L, which have fewer seats, do not.

Under this rule the number of passenger seats is based on the current configuration of each airframe, not its certified seating. Noise-generation levels used in the process are those from the initial type certification noise testing results for each model.

The FAA has concluded that while the correlation between ranking of certification noise levels and ranking of audibility duration is inexact, “aircraft that meet the GCNP quiet-aircraft-technology designation are consistently less audible than those that do not. Therefore it is reasonable to expect that replacing noncompliant aircraft with larger, GCNP quiet-aircraft-technology-designated aircraft should produce marked improvement toward substantial restoration of natural quiet,” the Holy Grail of the Grand Canyon National Park Overflights Act.

Ever since the act was passed in 1987, pro- and anti-aviation interests have debated the definition of “substantial restoration.” Air-tour operators, professional aviation organizations and the FAA on one side and environmental activist groups such as the Sierra Club, the Grand Canyon Trust, and the Friends of Grand Canyon– supported by the U.S. National Park Service (NPS) and Grand Canyon National Park Service (GCNPS)–on the other, remain largely unreconciled.

Environmentalists have repeatedly stated their wish to eliminate all general aviation overflights of the Grand Canyon but, realizing that is impossible, have encouraged the NPS to work with the FAA to satisfy the Overflights Act mandate. Air-tour operators have stated their belief that they have already essentially satisfied the intent of the law only to “have the bar raised” in front of them.

A Polarizing Issue

Comments made during the NPRM period reflected the relative positions. The Sierra Club conceded that some incentive is appropriate for operators who retrofit existing aircraft to meet the GCNP quiet-aircraft standard, but only if it does not compromise the “restoration of natural quiet.”

The group opposes new incentive routes through existing no-fly zones, but conditionally supports operational incentives for more flights of aircraft with lower noise signatures. The GCNPS opposes any increase in the total number of tour operations as an incentive for converting to noise-efficient aircraft. Friends of Grand Canyon supports the proposed noise efficiency approach only if it will substantially reduce the number of flights.

On the other hand, the Aerospace Industries Association (AIA), Helicopter Association International (HAI) and U.S. Air Tour Association (USATA) recommend incentives for research and development into noise-reduction technology to both manufacturers and others to develop STC solutions. AIA favors direct government support for R&D in developing new helicopters or modifying existing machines, while HAI calls for tax incentives to operators purchasing quiet aircraft technology equipment. All three organizations agree that operators should be allowed a higher number of operations within Grand Canyon National Park as more noise-efficient aircraft enter service.

The FAA expects to make recommendations regarding new “quiet aircraft technology-only” routes and corridors to the rulemaking committee of the National Park Overflights Advisory Group, which is composed of representatives from the FAA, the NPS, environmentalists, air-tour operators and other government and aviation interests.