Tycho Celchu was born on Alderaan, but chose to attend the Imperial Naval Academy to become a starfighter pilot. One of his main instructors was Soontir Fel, and his classmates included Biggs Darklighter and Derek "Hobbie" Klivian, with whom he became friends. Fel was a good instructor and Tycho was one of the classes best pilots, though he was never able to shoot down Fel in any of their simulations.
After graduation, Biggs and Hobbie defected to the Rebel Alliance, which tainted Fel's reputation. Tycho became a TIE pilot on the Star Destroyer Accuser. On his 21st birthday, Tycho was communicating with his family on Alderaan, when suddenly the communication cut out. He believed it was merely interference and planned on giving his father a hard time about it next time they spoke, but soon he found out that Alderaan had been destroyed by the Death Star.
This was the turning point for Tycho, who decided to join the Rebellion. While on leave from the Accuser, he never returned. After making his way to the Rebellion shortly after the Battle of Yavin, Celchu and Klivian were reunited, and he also befriended Wedge Antilles. Tycho was promoted to the rank of captain shortly before the Battle of Hoth, where he flew with Rogue Squadron for the first time. Rogue Squadron's founder, Luke Skywalker, would later leave Rogue Squadron to focus on Jedi training. Antilles would become the squadron's new commander, with Celchu as his right-hand man.
Tycho flew an A-wing fighter with Green Squadron at the Battle of Endor, as his X-wing was not in flyable condition at the time. His was one of several fighters to make the run through the second Death Star, but he flew out of the station to draw TIE fighters away from Wedge and Lando Calrissian.
Approximately a year after the Battle of Endor, Tycho volunteered to fly an intelligence gathering mission into Coruscant, but was captured before he could be extracted. He spent time in Ysanne Isard's Lusankya prison, which also contained a brainwashing facility used to create sleeper agents. Isard failed to break Tycho and he was moved to a less secure facility, where he managed to escape, remembering little of his time in Lusankya. Due to his time in Lusankya, the New Republic suspected him of being an Imperial agent, but could not bring themselves to remove him from their ranks. They allowed him to return to service, but put great restrictions on his personal liberties while Wedge Antilles was rebuilding Rogue Squadron.
During the Battle of Coruscant, where the New Republic reclaimed the galactic capital from the Empire, fellow Rogue Corran Horn was seemingly killed when his Z-95 Headhunter crashed. Celchu was considered the prime suspect in the death of Horn, and was put on trial for his murder. Celchu seemed close to being convicted, until Horn, who had survived the crash and escaped Lusankya, appeared at the trial.
Isard fled Coruscant to take a leadership position on the planet Thyferra, the galaxy's primary source of bacta. New Republic regulations against interfering with planetary governments led the members of Rogue Squadron to resign their commissions and operate as a fully independent group to take Isard down. Following Isard's apparent death at the Battle of Thyferra, the Rogues returned to Coruscant. Celchu became the new Rogue Leader, as Wedge Antilles formed a new unit, Wraith Squadron. After the Wraiths were reassigned to New Republic Intelligence, Antilles returned to the position of Rogue Leader, with Celchu as his second-in-command.
Celchu served with Rogue Squadron during the campaign against Grand Admiral Thrawn, and played a key role in the diplomatic mission to persuade the planet Adumar to join the New Republic. He married New Republic Intelligence agent Winter shortly afterward, and retired from military life. He would later return to combat when the Yuuzhan Vong invaded the galaxy, and also taught Wedge's daughter Syal how to fly starfighters during the Second Galactic Civil War.