A loud noise heard all around the eastern Darling Downs had southern Queenslanders scratching their heads, until the Air Force put up their hand.

"F/A-18F Super Hornets were undertaking essential 'intercept' training in the 'western airspace' of RAAF Base Amberley, which incorporates the Toowoomba region," a Defence spokesperson says.

"Regrettably the training was louder than anticipated, and some residents experienced more aircraft noise than usually occurs, when Air Force uses the western airspace...our pilots and crews need experience in a range of environments. This includes day and night flying, high and low altitude flying (below 500 feet or 150 metres) and bombing and strafing practice."

The Airforce is investigating the "disruption".

Jo from Warwick called ABC Radio to say "I heard a big loud clap of 'thunder'...on a clear night. And I said to my son, 'well, that cloud came up quickly, I wonder if it is going to rain.' Not even thinking it was anything else!"

The 'western airspace' will be used by Air Force again this week on Thursday night until 9pm; and Friday until 5pm. More day flying is planned during the first week of September.