The callsign was used by Pedrin Gaul of the Massassi Group during the battle over Scarif; however, Gaul would be killed in the battle, leaving the position vacant. It was later taken up by Luke Skywalker when he joined the Massassi Group shortly before the Battle of Yavin, and he would use this callsign in that battle as well as in several subsequent missions. After Skywalker destroyed the first Death Star, the callsign became synonymous with the actual X-wing fighter he flew. Grizz Frix used the callsign during the Battle of Endor -- Wookieepedia, the Star Wars Wiki