The Lockheed AP-3C Orion is a specialized variant of the P-3C Orion, developed specifically for the Royal Australian Air Force (RAAF). The AP-3C was not a new-build aircraft; instead, it was the result of a comprehensive upgrade program conducted between 1997 and 2005 on 18 existing P-3C airframes originally manufactured by Lockheed in the United States. This modernization program, which involved Boeing Australia as a major industrial partner, focused on updating the aircraft's avionics, sensors, and mission systems. Due to systems integration problems, the program took three years longer than originally anticipated, reaching final completion in 2005.
Derived from the Lockheed L-188 Electra turboprop airliner (which first flew in 1957), the AP-3C was designed for a diverse set of roles, including anti-submarine warfare (ASW), anti-surface warfare (ASuW), maritime surveillance, and search and survivor supply. To support these missions, the aircraft was equipped to carry Mk 46 torpedoes, sea mines, and AGM-84 Harpoon anti-ship missiles. A specialized sub-variant, the AP-3C(EW), was created by modifying two of the 18 aircraft to include electronic and signals intelligence (ELINT/SIGINT) suites.
Operated by No. 92 Wing at RAAF Base Edinburgh, the AP-3C fleet saw extensive service. This included ten years of operational service in the Middle East Area of Operations (MEAO) supporting missions in Iraq and Afghanistan, completing 2,400 missions. The aircraft also played critical roles in regional security through Operation GATEWAY, border protection via Operation RESOLUTE, and fisheries surveillance during Operation SOLANIA. Notably, the AP-3C was a primary aircraft used in the search for Malaysia Airlines flight MH370. The standard patrol fleet was retired in 2019 as the RAAF transitioned to the Boeing P-8A Poseidon, while the two AP-3C(EW) aircraft remained in service until December 2023.