6/20/2013 - Secretary of the Air Force Michael Donley bids farewell to Airmen while departing from the Pentagon June 20, 2013, for the final time as the Air Force secretary. Donley was confirmed as the 22nd secretary of the Air Force Oct. 2, 2008. He served as the acting secretary since June of that year, as well as for seven months in 1993, making him the longest serving secretary in the history of the Air Force. His departure ceremony is June. 21. (U.S. Air Force photo/Andy Morataya) (U.S. Air Force graphic/Corey Parrish)

6/20/2013 - Secretary of the Air Force Michael Donley bids farewell to Airmen while departing from the Pentagon June 20, 2013, for the final time as the Air Force secretary. Donley was confirmed as the 22nd secretary of the Air Force Oct. 2, 2008. He served as the acting secretary since June of that year, as well as for seven months in 1993, making him the longest serving secretary in the history of the Air Force. His departure ceremony is June. 21, 2013. (U.S. Air Force photo/Michael J. Pausic)

6/20/2013 - Secretary of the Air Force Michael Donley bids farewell to Airmen while departing from the Pentagon June 20, 2013, for the final time as the Air Force secretary. Donley was confirmed as the 22nd secretary of the Air Force Oct. 2, 2008. He served as the acting secretary since June of that year, as well as for seven months in 1993, making him the longest serving secretary in the history of the Air Force. His departure ceremony is June. 21. (U.S. Air Force photo/Andy Morataya)