What’s a sonic boom?

A sonic boom is a thunderous noise caused by an object, like an aircraft, moving faster than the speed of sound. (That’s about 750 miles per hour at sea level, according to the Air Force .) How long it takes a sonic boom to reach the ground, depends on the plane’s altitude, which can mean anywhere from “two to 60 seconds after flyover,” the Air Force states. As the object zooms through the sky, the air molecules around it are pushed aside with tremendous force, generating shock waves along its flight path. The release of pressure, following the shock waves’ buildup, is heard as the sonic boom, according to NASA. Generally, a larger aircraft will cause stronger shock waves, and therefore, a louder sonic boom.

Why does the military perform them?

Military aircraft cause sonic booms when they travel very, very fast — either for testing and training purposes, or during emergencies. Most Air Force fighter aircraft are capable of reaching the supersonic speed that causes sonic booms. “Supersonic training flights that simulate actual combat conditions are necessary to ensure the success and survival of aircrews during wartime,” the Air Force states. The military has conducted faster-than-sound test flights since 1947 , when the Bell X-1 rocket engine-powered aircraft , piloted by Air Force Capt. Charles “Chuck” Yeager, became the first airplane to fly faster than the speed of sound, according to the National Air and Space Museum .

Are sonic booms harmful?

Sonic booms can shatter glass , but there is generally little risk for people on the ground. “Buildings in good repair should suffer no damage by pressures of less than 16 pounds per square foot,” the Air Force states. “And, typically, community exposure to sonic boom is below two pounds per square foot.” Whenever possible, the government requires that supersonic flights be conducted “over open water, above 10,000 feet and no closer than 15 miles from shore. Supersonic operations over land must be conducted above 30,000 feet or, when below 30,000 feet, in specially designated areas,” the Air Force states. The designated areas for supersonic operations are approved by the Air Force and the Federal Aviation Administration. The strongest sonic boom ever recorded was produced by a F-4 flying at an altitude of 100 feet. It did not cause injury to the researchers who were exposed to it, according to the Air Force.

What causes a sonic boom, and is it harmful?

By Anumita Kaur

June 4, 2023 at 8:56 p.m. EDT

A U.S. Air Force F-16 Fighting Falcon fighter jet, manufactured by Lockheed Martin Corp., performs maneuvers at the Singapore Airshow held at the Changi Exhibition Centre in Singapore, Feb. 6, 2018. (SeongJoon Cho/Bloomberg)

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Fighter jets from Joint Base Andrews, Md., caused a sonic boom to reverberate throughout the D.C. region, startling residents Sunday afternoon.

The F-16 jet aircraft were scrambled in response to a Cessna that authorities said was unresponsive when hailed, and later crashed in southwestern Virginia, according to North American Aerospace Defense Command.

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“The NORAD aircraft were authorized to travel at supersonic speeds and a sonic boom may have been heard by residents of the region,” NORAD officials said in a statement Sunday night.

It remains unclear why the Cessna crashed, but before NORAD officials provided an explanation for the loud noise, area residents had been questioning what happened over social media.

Here’s what to know about sonic booms: