Outgoing Air Force Chief of Staff Gen. David Allvin bid farewell to the service Friday in a retirement ceremony at a hangar in Joint Base Andrews, Maryland. While the event does not mark the exact end of Allvin’s tenure as the Air Force’s top officer, his departure is likely not far off . His nominated successor, Gen. Kenneth Wilsbach , encountered no serious bumps during his confirmation hearing Thursday, and senators appear likely to support him. Allvin unexpectedly announced his retirement