Grand Canyon National Park and the Colorado Plateau are areas that support wildlife and regeneration of the human spirit, all of which are compromised by motorized noise.

Website information about natural quiet and noise pollution within the Department of Interior National Park Service  and Grand Canyon NP

Natural quiet is not the only thing at risk with overflight air tours of the Grand Canyon. Deadly crashes have happened causing devastating losses such as This Flight in 1986  

Here is the Grand Canyon Chapter of the Sierra Club's letter to National Parks Director Jonathon B. Jarvis on Noise Polution in the Canyon 

Graph for East End Over flight.