In addition, unlimited noise would continue to permeate the entire park since there is no restriction on non-tour aircraft at elevations of 1300 to 9500 feet. This association finds that the NPS and FAA have failed in their responsibility to restore natural quiet to the park. However, GAMA states that limiting the use of one corridor to Category C aircraft is arbitrary and subjective. The FAA notes that these two areas are not affected by the Notice 97-6 proposal. Moreover, it has applied a flawed NPS noise model to justify the rules.
TOIL finds that there is insufficient incentive for converting to the new technology.
TOIL recommends maintaining a 40-minute canyon viewing experience and further urges the FAA to limit it to quiet technology only. GCA believes that FAA discriminated in favor of helicopters by giving them the lowest altitudes and preferred routes. Grand Canyon River Guides comments that there should be no flights through flight free zones. This commenter notes that the Havasupai also want these flights removed. The Guides believe that this is a non- essential route and that people will still book tours, regardless of the location of the route.