The Air Force is holding another training session in the massive Powder River Training Complex over the Northern Plains.
The Combat Raider training is scheduled Tuesday through Thursday, with several types of aircraft. The military says there's the potential for loud noises associated with sonic booms.
The Federal Aviation Administration approved quadrupling the training airspace to 35,000 square miles in March 2015. The expanded complex over the Dakotas, Montana and Wyoming officially opened in September of that year, with large-scale exercises such as the one this week limited to 10 days per year.
The training complex is the largest over the continental U.S.