The P-3 Orion is a four-engine turboprop aircraft developed by Lockheed and released in 1961. It is based largely on the L-188 Electra which was used as a commercial airliner. The primary function of the P3 Orion with the U.S. NAVY was anti-submarine and maritime surveillance. It is still used in this role by many foreign governments. Many P3 Orions have been converted for use as fire fighting aircraft.