Viper 4 is a Viper Starbuck pilots during the mission to track the flight path of Leiter's Eastern Alliance destroyer.
After Viper 4 lands on Terra in pursuit of Apollo, Starbuck is intercepted by members of the People's Nationalist Force, which he dispatches.
With the help of Brenda Maxwell, Starbuck returns to Viper 4 in an attempt to prove to members of the Precedium that he and Apollo are from another world. He leaves the planet and is told by John that the Eastern Alliance has launched its missiles at Terra, which will destroy four-fifths of the planet, unless he can contact Galactica and get them to use their lasers to take out the missiles (TOS: "Experiment in Terra").