Our congratulations on your excellent editorial "Peace for Grand Canyon (Dec. 19). The Department of the Interior's aircraft management plan (now awaiting FAA approval), while not perfect in every detail, is nevertheless a very commendable and long-overdue beginning effort toward restoring the natural quiet to major noise-sensitive parts of Grand Canyon National Park.
A key element of the plan, as mandated by Congress, is a two-year study of aircraft-sound impacts. We hope and anticipate that the more adequately funded research program will be far better than past studies. For example, all aircraft sound frequencies and their characteristics against a background of natural quiet should be carefully monitored. These more thorough and accurate studies should, in turn, help determine how meaningful incentives can best be implemented by which all air-tour operators can be encouraged to invest in quieter equipment and technology--as two major companies have already begun to do.
Such quieter-aircraft incentives, which are virtually absent from the present plan, are an essential ingredient of effective, long-term aircraft management not only over Grand Canyon but over all national parks throughout the country.
RUSSELL D. BUTCHER
Southwest and California
Nat'l Parks &