Tierfon Rebel Outpost Starfighter Squadron (X-wing) is the formal name for a small base in the Sumitra Sector, located on the planet Tierfon. Starfighters from this base participate in combat patrols and escort duty. While primarily an outpost of the Rebel Alliance Starfighter Command, the base is also used by a variety of other services within the Alliance; Ordnance and Supply, Intelligence, and Support Services ships frequently refuel here, and a small contingent of Spec Force troops call the base home. All told, over 150 beings are at the outpost at any given time.
The Sumitra Sector is in the Expansion Region and is made up of 12,387 planets and moons. Notable systems within the sector include Alk'Lellish, Boordii, Flax, Geedon, Ptera, Reegian, Thustra, and Tocan. The sector also includes the Oolex Pulsar.
The Sumitra Sector is not heavily occupied by the Imperial Navy and thus the base at Tierfon was, until recently, considered a bit of a training post--a place where pilots and crews could learn the craft of starfighter operations before being rotated to more front-line outposts.
A squadron known as the Tierfon Yellow Aces once called the outpost home. Famous pilots Wes Janson and Jek Tono Porkins were once based here with the old squadron. Porkins was killed in action during the attack run on the Death Star above Yavin-4.
The Yellow Aces flew Y-wings from Tierfon until the disaster of the Battle of the Tocan system. Although most of the pilots survived the brutal engagement, but the amount of damage done to their starfighters was well beyond the ability of the Tierfon ground crews to repair in the field. The Yellow Aces squadron was effectively disbanded and all space-worthy craft were sent elsewhere for refit and refurbishment. Pilots from the squadron were re-assigned, mostly to Red Squadron on Yavin-4.
Two of the surviving Tocan system Y-wings are still present on Tierfon, parked down in the valley below the cliff-face launch bay. Both are BTL-S3 craft, and both are in need of extensive repairs before they would be considered operational again (they were damaged in the battle, then stripped for parts to make the other Y-wings space-worthy).
Taking the place of the now-defunct Yellow Aces is Black Squadron, part of 3 Wing, 8th Starfighter Group, Sumitra Sector Command. Black Squadron had barely been assigned to Tierfon before the events of Alderaan and Yavin-4 forced the outpost's status to be boosted to "full active". At the same time, StarCom immediately re-assigned four of Black Squadron's twelve X-wings to Alliance HQ.
Star Wars Sourcebook, WEG, 1987 (Slavicsek, Smith)
Star Wars The Essential Atlas, LucasBooks, 2009 (Wallace, Fry)