Twelve years ago, at about this time, I was flying over Alton, New Hampshire, when I heard a strange radio conversation from the airport at Sanford in Maine between the office and a pilot taking off. The office told him to abort. The pilot replied that he was already off the ground. "Return," said the office. "All air traffic is grounded." I was heading "around the mountains" on that glorious early autumn day, so I landed at Moultonborough aiport for gasoline and to check out the situation. There I was told that "a 707" had crashed into a building in New York and all air traffic was indeed grounded. With great good luck, I did get permission to fly back to my home airport, during which flight I may have been the only pilot airborne in the United States, or anyhow the only one within radio distance.
The following year, I made the annual around-the-mountain flight. It was another gorgeous day, and when I surfed over the height-of-land at Kancamagus Pass, the parking lot was full of tourists taking photographs of my Piper Cub. For my part, I extended my right middle finger in the direction of Osama bin Laden.
I made the 9/11 pilgrimage every year thereafter, whenever the weather was favorable, which was about half the time. The last one was on September 11, 2011, just before I turned eighty. I then grounded myself in the interests of public safety. The Cub wouldn't do any damage to a New York skyscraper, but it could scare the daylights out of somebody on the ground, if an octogenarian lost control of it.