Watch military planes perform low-altitude training flights over central Pa.

There was a reason for those low-flying aircraft soaring through central Pa. on Thursday.

The 193rd Special Operations Wing conducted special training flights that were designed to honor the victims of the Sept. 11, 2001 terrorist attacks.

The mass formation took off from Harrisburg International Airport, and crossed through Fort Indiantown Gap, Middletown, Lewisberry, Dillsburg, Shippensburg and spots along the West Shore.

The tribute was flown in accordance with Air Force regulations and will be flown at low altitudes to practice the mission sets for the wing’s MC-130J Commando II, according to a press release.

You can see footage of the formation in flight in the video below .