The air traffic control tower at Maryland's Frederick Municipal Airport is one of the 20 busiest in the country a year after it opened. Controllers handle 300 to 500 operations per day at the contract tower -- almost 108,000 flights in its first year. "Without a tower, pilots can do whatever they want to do. With a tower, you have layers built in of separation standards," said Todd Johnson, tower manager. A lot of the traffic comes from area flight schools, and the tower has also helped to limit planes from accidentally flying into nearby Camp David airspace.