Lockheed P-3 Orion – a four-engine turboprop anti-submarine and maritime surveillance aircraft developed for the United States Navy and introduced in the 1960s. Lockheed based it on the L-188 Electra commercial airliner. The aircraft is easily recognizable by its distinctive tail stinger or “MAD Boom”, used for the magnetic detection of submarines.
Over the years, the aircraft has seen numerous design advancements, most notably to its electronics packages. The P-3 Orion is still in use by numerous navies and air forces around the world, primarily for maritime patrol, reconnaissance, anti-surface warfare and anti-submarine warfare. A total of 734 P-3s have been built, and during 2012, it joined the handful of military aircraft including the Boeing B-52 Stratofortress and Boeing KC-135 Stratotanker that have served 50 years of continuous use by the United States military.
Several P-3 aircraft have been N-registered and are operated by civilian agencies.
- The US Customs and Border Protection has a number of P-3A and P-3B aircraft that are used for aircraft intercept and maritime patrol.
- NOAA operates two WP-3D variants specially modified for hurricane research.
- P-3B, N426NA, is used by National Aeronautics and Space Administration (NASA) as an Earth science research platform, primarily for the NASA Science Mission Directorate’s Airborne Science Program.
- Aero Union, Inc. operated eight ex-USN P-3A aircraft configured as air tankers, which were leased to the U.S. Forest Service, the California Department of Forestry and Fire Protection and other agencies for firefighting use.
- CP-140A Arcturus – maritime patrol aircraft operated by the Royal Canadian Air Force. The aircraft, based on the Lockheed P-3 Orion airframe, was used for crew training, general maritime surface reconnaissance (detecting drug operations, smuggling of illegal immigrants, fisheries protection patrols, pollution monitoring, etc.), search-and-rescue assistance and Arctic sovereignty patrols.
- MAD (Magnetic Anomaly Detector) – an instrument used to detect minute variations in the Earth’s magnetic field. The term refers specifically to magnetometers used by military forces to detect submarines (a mass of ferromagnetic material creates a detectable disturbance in the magnetic field); military MAD equipment is a descendent of geomagnetic survey instruments used to search for minerals by detecting their disturbance of the normal earth-field.