Last October, while marveling over the gushing Riverside Geyser in Yellowstone National Park, I happened to look up and saw a small jet making circles overhead. Obviously, the pilot and his passengers wanted to watch the eruption as well. According to the National Park Service, that was the only authorized overflight for the month in Yellowstone, but across the National Park System there were tens of thousands of overflights last year that, while providing a bird's eye view of spectacular scenery, can be an annoyance to those on the ground.