 The two airlines' operating certificates were merged in September 2007.After initially using the "CACTUS" callsign for the west fleet and "USAIR" for the east fleet, all aircraft began flying under a single "CACTUS" callsign and ICAO code "AWE" in September 2008.Former America West aircraft were distinguished apart from US Airways pre-merger aircraft by their use of registrations ending in "-AW", while pre-merger US Airways aircraft used registrations ending in "-US".