"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.