The United States Air Force, also known by its initials USAF, or more popularly as the Air Force, was a branch of the military of the United States of America on Earth. The Air Force was the branch of the military that concentrated mainly on aerospace and related services. Originally, the Air Force was part of the United States Army, when it was known as the United States Army Air Corps. On September 18, 1947, the Air Force was created as a separate branch of the military. The Air Force used its own special rank structure for enlisted personnel, but the officer rank structure was based on that of the U.S. Army.
In the late 1960s, Captain John Christopher served as a fighter pilot in the Air Force. In July 1969, he was dispatched to intercept a large unidentified flying object that appeared over the United States. This object was the USS Enterprise, which had been slingshot nearly 300 years backwards in time. When the Enterprise tried to put a tractor beam on his fighter jet, Bluejay 4, it broke apart under the strain, and Christopher was beamed on board. Captain James T. Kirk and Lieutenant Hikaru Sulu then infiltrated an Air Force base to retrieve the photographs taken by the fighter's cameras. (TOS episode: "Tomorrow is Yesterday")
Unaware of Kirk's plans, Agents Gary Seven and Roberta Lincoln, posing as Air Force officers, also infiltrated the same base in order to retrieve evidence of the Enterprise's presence in the past. (TOS - Star Trek: Assignment: Earth comic: "Yesterday, Today and Tomorrow")
- See also: United States Armed Forces