FLAGSTAFF, Ariz. (AP) -- Air tour operators that use aircraft with quiet technology will be able to fly more people over the Grand Canyon.
The Federal Aviation Administration said it plans to release 1,721 flight allocations this year that had been abandoned to those commercial tour operators, as long as their active fleet doesn't increase noise in the park overall.
An extensive transportation bill passed in 2012 requires the FAA and the National Park Service to come up with incentives for quiet air technology at the canyon. Earlier this year, the Park Service reduced the fees for air tour operators that use the technology from $25 per flight to $20.
The FAA determines whether aircraft is considered quiet by using a formula that takes into account noise certification levels and the number of seats.
The FAA's decision to release more flights was published this week in the Federal Register. It would bring the total number of air tours allowed per year to nearly 94,000, though not all of those are used. FAA data show that almost 52,000 commercial flights took passengers on sightseeing tours over the Grand Canyon in 2012.
Converting an aircraft to meet the definition of quiet does not necessarily mean the aircraft will be quieter. Operators could, for example, add more seats to existing aircraft or switch out engines to satisfy the standard.
Nearly 50 of the flight allocations being freed up by the FAA are for the Dragon and Zuni Point corridors, which take passengers over the widest and deepest part of the canyon, and to the eastern edge. Those are expected to be used up quickly. While allocations from those corridors can be transferred to other areas of the canyon, the remaining 1,672 flights cannot be conducted within those corridors.
Grand Canyon National Park Superintendent Dave Uberuaga said he expects the effect to visitors will be minimal.
"An extra 49, when you're talking about one every two minutes, I don't think anybody will actually physically notice them," he said. "You know there is more noise because there are 49 (more) flights, but no one is going to notice it on the ground, and that's why we're comfortable with it."
Jim McCarthy of the Sierra Club disagrees. He said he'd rather see the abandoned allocations retired rather than increasing the number of flights that affect backcountry hikers seeking solitude and quiet in the canyon's wilderness. He said safety also could become an issue with more aircraft in the skies.
"It's incrementally in the wrong direction," he said.
The Park Service wanted to make 67 percent of the canyon quiet for three-fourths of the day or longer, but the provision in the 2012 transportation bill forced a change to make half of the park free from commercial air tour noise for at least 75 percent of the day and provided incentives for quiet air technology.
Many of the tours originate from Las Vegas.
Arizona Sen. John McCain said Wednesday that he is pleased that more air tours will be available to park visitors.
"Air tours, and the unique sightseeing experience they provide, are an important part of the northern Arizona economy," he wrote in a statement.
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