Tommy Kovaks served in the operations division and command division while aboard the Enterprise.
In 2266, he assisted Lieutenant Commander Montgomery Scott with the task of opening the locked door to the engineering control room, which had been taken over by Kevin Riley while under the influence of the Psi 2000 virus. (TOS episode: "The Naked Time")
In 2267, during his rotation in the operations division, Kovaks manned the helm during the Federation-Klingon War of 2267 as the Enterprise confronted multiple D7-class Klingon battlecruisers. (TOS episode: "Errand of Mercy")
By 2270, he was serving in the command division, continuing as relief helmsman during periods when Sulu assumed command. During their encounter with the Hollow Planet, Kovaks adjusted the ship from an erratic orbit to a pursuit course when the artificial planet suddenly veered away from them. (TOS - New Visions comic: "The Hunger")
Later that year, he struggled to compensate against increasingly erratic waves of temporal disruption from the Guardian of Forever while in orbit of Gateway. With so many waves that Pavel Chekov was unable to plot them, Sulu took over from Kovaks so as to evade them by instinct. (TOS - New Visions comic: "An Unexpected Yesterday")
- TOS episode: "The Naked Time"
- TOS episode: "Errand of Mercy"
- TOS - New Visions comic: "Sam"
- TOS - New Visions comic: "The Hunger"
- TOS - New Visions comic: "An Unexpected Yesterday"