Air National Guard Breaks Sound Barrier

A Massachusetts Air National Guard fighter jet flying a routine training mission over the New Hampshire-Vermont border has inadvertently broken the sound barrier.

The National Guard says the pilot of the F-15C Eagle was completing qualification training in a controlled military airspace Thursday morning when he flew at just under 700 mph at 20,000 feet above sea level. (Associated Press)

The area isn't among those designated by the Air Force for supersonic flights.