The United States Air Force Thunderbirds, one of the world’s oldest air demonstration teams, are under scrutiny following an incident during a practice flight for the Chicago Air & Water Show. On August 15, ahead of their scheduled performances at North Avenue Beach, reports emerged that a sonic boom shattered windows in three Lake View East buildings.
Fox reported that the damage was caused by two sonic booms from at least one aircraft allegedly flying supersonic. However, a USAF spokesperson told the Chicago Sun-Times that “jets did not go supersonic at any point during the demonstration.” In contrast, Matthew Clarke, a local academic, stated:
"Those were clearly sonic booms. Even though the global flow may not be faster than the speed of sound, there are places locally faster than the speed of sound, creating shock waves. While I can’t say that the whole plane went supersonic, I can say, from the video, shock waves [were created] from parts of the aircraft."