This is a rare moment of relaxation for an environmental mediator. Several years ago I was plunged into the war over aircraft noise at Grand Canyon. For decades environmentalists and recreation interests had been pushing Congress and the courts for some regulations on the air tours over the Canyon. They yearned for quiet in which to enjoy and contemplate the wonders of this world-famous site. Certain favorite trails were directly under the flight pattern of the helicopters and fixed wing planes that offered tourists a spectacular experience, viewing the Canyon from the air. Defending themselves, the air tour operators pointed out that they made it possible for people unable to visit the Canyon by foot or by boat to have a remarkable experience -- as breath-taking and life-changing as those hiking and rafting. Besides, they argued, their businesses had a right to flourish as National Park Service concessionaires. There were other interests as well in this complex conflict. The Fish and Wildlife Service was responsible for the protection of endangered species, including Condors who nested in the Canyon walls. Four Indian tribes had interests -- some economic and some religious -- in the Canyon's resources. And finally there was the commercial aircraft industry. Hundreds of coast-to-coast jets flew daily directly over the Canyon at 25,000 feet or higher. They wanted to be sure that their routes were not impacted by any new regulations on aircraft over the Canyon. The two agencies responsible for addressing the aircraft noise issue and "restoring natural quiet" to the Canyon (by order of Congress) were the Park Service and the Federal Aviation Administration. Using a regulatory negotiation process they formed the Grand Canyon Working Group, whose 18 members represented all the variety of interests listed above, and a couple more. In 2004, I was hired to wrangle the group into consensus. We met for two years and faced challenges that I expected, and some that I didn't. With a deep history of hostility between the air tour operators and the environmental advocates, establishing even minimal trust was difficult. They had been battling each other for decades and were bitter and bloodied, and working through past grievances took time and a lot of emotional energy from all of us. Second, the subject of noise technology is very complex. How can noise be measured, given background sounds, weather conditions, pitch of sound, and many other variables? These challenges I expected. The goal was to achieve the “restoration of natural quiet,” as mandated by Congress and established by scientists. The first task was to agree on the current level of aircraft noise and the sources of that noise. The group agreed to accept the results of a model and analysis by an independent agency. Once the noise level and sources were known, there would be a basis for negotiating reductions in air tours. Or that was the plan. But the study showed that the major contributor to aircraft noise over the Canyon over a 24 hour period was the commercial jet traffic, not the air tours. The air tour operators rejoiced. "It's not us!" The commercial jetliners dug in their heels, insisting that there was no way commercial air traffic could be diverted to avoid the Canyon. It was a matter of economics and safety. We were stuck. Even if the air tours were completely eliminated the noise level would exceed the "natural quiet" levels. The power at the table shifted considerably, as did my mediator's strategies. Unable to achieve our goal of restoring natural quiet, we lowered our expectations and developed 23 recommendations for the two agencies that would enhance the experience for visitors on the ground and on the river. These included a seasonal shift in air tour routes, new signage on hiking trails, and phase-in dates for new quieter aircraft technology. Although we did not reach consensus on these recommendations, the Park Service relied heavily on them as they moved forward.