Amid fighter jet training exercises by the 104th Fighter Wing Massachusetts Air National Guard, a loud boom was heard and felt around the Monadnock Region shortly after 2 p.m. Wednesday
People within a 20-mile radius of Keene, N.H., said their houses shook with the noise.
But while the Massachusetts Air National Guard confirmed it was conducting training exercises in the area, it denied its jets produced a “sonic boom,” the noise of a jet breaking the sound barrier.
Supersonic flight is illegal, according to a 1973 regulation by the Federal Aviation Administration.
“Air traffic control officials confirmed via their tracking systems that the sound barrier was not broken by our jets,” the Massachusetts Air National Guard said in an email statement.
Pilots verified their speeds were subsonic from the jet’s on-board recording systems, according to the statement, which also said jets were flying at altitudes between 10,000 and 12,000 feet, alongside aircraft from the Civil Air Patrol.
“Therefore, the sound was caused by normal jet engine noise, and was not a sonic boom,” the statement said.
The Massachusetts Air National Guard did not notify the New Hampshire Air National Guard or local media of Wednesday’s training exercises.
Training by the 104th Fighter Wing has caused already caused two sonic booms this year in New Hampshire, according to Lt. Col. Gregory Heilshorn, a spokesman for the New Hampshire Air National Guard.
The Westfield, Mass.-based 104th previously conducted exercises in southwestern New Hampshire in January, and officials sent out notification at that time.
No further details were available.