United States Air Force

The United States Air Force, also known by its initals 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, Air Force was part of the United States Army, when it was known as the 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.

Captain John Christopher was a member of the Air Force. A fighter pilot, he was dispatched to intercept a large unidentified flying object that appeared over the United States. This object was the USS Enterprise (NCC-1701), which in the process of escaping the gravity of a singularity had been slingshot 300 years backwards in time. When the Enterprise tried to put a tractor beam on his fighter jet, the jet was unable to handle the strain and broke up. Christopher was beamed on board. Kirk was going to take him back to the 23rd century, but changed his mind when he learned that Christopher's son would command the first space probe to Saturn. Spock was able to use a forward slingshot maneuver to return the Enterprise to the 23rd century, and to also return Christopher to his own time, unaware of what had happened. (TOS episode Tomorrow is Yesterday)