WESTFIELD, Mass. (AP) -- A Massachusetts Air National Guard fighter jet flying a routine training mission over the New Hampshire-Vermont border inadvertently broke the sound barrier, rattling some residents and sparking concerned calls to police.
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, National Guard spokesman Maj. Matthew Mutti said.
The area isn't among those designated by the U.S. Air Force for supersonic flights, he said.
Residents of the Vermont city of Bradford and the New Hampshire communities of Lyme and Orford may have heard the resulting sonic boom, according to a statement released by the National Guard.
Orford police Officer Michael Foster said the sonic boom prompted about a half dozen residents to call his department. "It was just concern because of the noise," he told The Associated Press.
Dispatchers at the Hanover, N.H., police department, who take calls for 23 towns, told the Valley News of Lebanon, N.H., that they received 15 calls related to the sonic boom.
The National Guard says it didn't intend to cause undue concern.
The military restricts supersonic flights to specific operating areas in an effort to avoid disturbing communities over which the jets are flying. The aircrafts are allowed to exceed the speed of sound when flying "15 miles off the coast at a specified altitude ...for the same reasons we don't fly supersonic over the land," Mutti said.
The F-15s -- extremely maneuverable tactical fighters designed to enable the Air Force gain and maintain air supremacy over the battlefield -- secure the northeastern United States airspace.
"We will continue to work hard to prepare our pilots to fulfill our mission of air superiority, and our commitment to the community's safety is always paramount, never intending to cause undue concern," said Col. Kenneth Lambrich, vice commander of the 104th Fighter Vice Wing based in the western Massachusetts town of Westfield.