WASHINGTON (AP) — The extraordinary scene of U.S. fighter jets getting ready to strike a Chinese balloon had many people along the Carolina coast straining their necks and pointing their smartphones to the sky to capture the moment of impact.

But a group of aviation enthusiasts was, instead, intently scanning radio frequencies for the exchanges between the pilots who would follow as Huntress, NORAD’s eastern air defense sector controller, tracked the exact distance as two Air Force F-22 fighter jets closed in on the target.

The pilots had to balance striking the balloon when it was at least six miles (10 kilometers) offshore — the distance NASA had advised the military allow to keep debris from falling on land — with ensuring it was still in U.S. territorial airspace.

“Five miles offshore,” Huntress advises in a transmission that was captured by aviation hobbyist Ken Harrell, in a recording that was authenticated by NORAD.

“Frank One is switches hot,” the first F-22 reports. The call sign “Frank” was given to both aircraft to honor 2nd Lt. Frank Luke, who earned the Medal of Honor in World War I for downing multiple balloons and aircraft.

“Frank Two is switches hot,” the second F-22 radios in.

When Huntress calls out that the balloon is exactly six nautical miles out, Frank One takes the shot.

“The balloon is completely destroyed!” radios an F-15 fighter jet that also took part in the mission, advising quickly that “there appears to be metal chaff clouds. … It’s definitely metal breaking apart.”

This audio, which was first reported by The War Zone, wasn’t on the civilian radio frequencies that commercial pilots use. The Air Force pilots were communicating on an unencrypted military frequency that the North American Aerospace Defense Command uses to conduct missions to secure the eastern United States, under the control center named Huntress.

Aviation enthusiasts with the right radios scan for Huntress missions and other military flights as a hobby, calling out exercises.

Ken Harrell, a 68-year-old retiree from Summerville, South Carolina, is one of those enthusiasts. On Saturday, he recorded the exchange of the balloon shootdown.

NORAD confirmed the authenticity of the recording to The Associated Press in a statement.

When Harrell got started a few years ago, he said he “bought the right kind of scanner, put up, you know, a decent antenna and a lot of software to connect to the scanner and just started listening.” He said the scanner only cost about $160 to get started.

On Saturday, he got a call from a fellow enthusiast who said Huntress was guiding F-22s in to hit what the Pentagon has said was a spy balloon and China has insisted was a civilian weather balloon.

“He says, get on the scanner, man! Huntress has been controlling the F-22 Raptors, you know for the balloon, they’re gonna do it,” Harrell said. “So I jump up, crank up everything, and started listening in.”

When Harrell heard the pilots’ and controller’s voices, “I was excited,” he said. “I’ve listened to a lot of other stuff — fighters practicing, intercept exercises, and that’s cool, but when I first turned the scanner on and it went to my local Huntress frequency, it was pretty apparent: This was a mission. Boom.”