At some point, he enrolled in Starfleet and rose to the position of chief engineer on the science vessel USS Tobias which was under the command of Commander Christine MacDonald. By 2374, when the Virogen Crisis was infected Federation planets, Barc along with the rest of the USS Tobias's crew beamed down onto Chal where they were helping with relief efforts. As their ship had not been resupplied for months, Barc was tasked with the repair of their equipment. Commander MacDonald assisted him in an attempt to repair the Replicator's but without the proper components he was unable to do so until Christine suggested using parts from the Tricorder's the had.
During that time, he listened to his Captain's opinion that the mysterious stranger that had arrived on Chal was in fact James T. Kirk. Barc like his colleague Andrea M'Benga were both skeptical as they both believed he had died at Veridian III and was buried by Captain Jean-Luc Picard. When a group of Orion pirates attacked Chal along with their ship, Barc returned to the USS Tobias's where Commander MacDonald told him to beam the suspected Kirk onto the ship to help lead them against the attack. It was then that Kirk took command of the Tobias and though Barc was argumentative about it, he agreed to allow the more experienced Captain to help them.
The USS Tobias was later taken to Vulcan when they learnt that the attack on Chal was not made by Orions but in fact by Vulcan's. During their time there, they were arrested by the Vulcan authorities who believed them responsible for an attack on the Gonthar District and that they may have mutined against Starfleet. Barc was accompanied by his colleagues along with Ambassador Spock and his aide Srell to the holocell's at the orbiting Vulcan space station whilst their ship was impounded. When Christine attempted to escape the Holoemitter's in their cell, he explained the futility of the task but MacDonald managed to evade the sensor's of the detention cell. This allowed them to escape onto the USS Tobias where Barc was successful in reactivating the ship even though they had only a few crew. The ship later managed to evade the USS Enterprise as it journeyed onto Tarsus IV which was believed to be the suspected base of the Symmetrists who were responsible for unleashing the Virogen plague.
Barc was almost killed along with the crew when the Symmetrists beamed Transporter mines that nearly overwhelmed the ship but was saved by the timely intervention of the USS Enterprise. He later accompanied the crews of the two ship to the surface of Tarsus IV where he was impressed at the USS Enterprise's crews success at penetrating the planetary shield though he did mention of several techniques that could counter it. (TOS novel: Avenger)