The Lockheed P-3 Orion is 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.[4] The aircraft is easily distinguished from the Electra by its distinctive tail stinger or "MAD Boom", used for the magnetic detection of submarines. Over the years, the aircraft has seen numerous design developments, most notably in its electronics packages. Numerous navies and air forces around the world continue to use the P-3 Orion, primarily for maritime patrol, reconnaissance, anti-surface warfare and anti-submarine warfare. A total of 757 P-3s have been built and, in 2012, it joined the handful of military aircraft including the Boeing B-52 Stratofortress, Boeing KC-135 Stratotanker, Lockheed C-130 Hercules and the Lockheed U-2 that the United States military has been using for more than 50 years. The Boeing P-8 Poseidon will eventually replace the U.S. Navy's remaining P-3C aircraft. The P-3 has an internal bomb bay under the front fuselage which can house conventional Mark 50 torpedoes or Mark 46 torpedoes and/or special (nuclear) weapons. Additional underwing stations, or pylons, can carry other armament configurations including the AGM-84 Harpoon, AGM-84E SLAM, AGM-84H/K SLAM-ER, the AGM-65 Maverick, 127 millimetres (5.0 in) Zuni rockets, and various other sea mines, missiles, and gravity bombs. The aircraft also had the capability to carry the AGM-12 Bullpup guided missile until that weapon was withdrawn from U.S./NATO/Allied service. The P-3 is equipped with a magnetic anomaly detector (MAD) in the extended tail. This instrument is able to detect the magnetic anomaly of a submarine in the Earth's magnetic field. The limited range of this instrument requires the aircraft to be near the submarine at low altitude. Because of this, it is primarily used for pinpointing the location of a submarine immediately prior to a torpedo or depth bomb attack. Due to the sensitivity of the detector, electromagnetic noise can interfere with it, so the detector is placed in P-3's fiberglass tail stinger (MAD boom), far from other electronics and ferrous metals on the aircraft. Once on station, one engine is often shut down (usually the No. 1 engine – the left outer engine) to conserve fuel and extend the time aloft and/or range when at low level. It is the primary candidate for loiter shutdown because it has no generator. Eliminating the exhaust from engine 1 also improves visibility from the aft observer station on the left side of the aircraft. On occasion, both outboard engines can be shut down, weight, weather, and fuel permitting. Long deep-water, coastal or border patrol missions can last over 10 hours and may include extra crew. The record time aloft for a P-3 is 21.5 hours, undertaken by the Royal New Zealand Air Force's No. 5 Squadron in 1972. Although the P-3 is a Maritime Patrol Aircraft, armament and sensor upgrades in the Anti-surface Warfare Improvement Program (AIP) have made it suitable for sustained combat air support over land. In what became known as the "Decade in the Desert", Navy P-3C crews patrolled combat zones in the Middle East and Southwest Asia. Since the start of the current war in Afghanistan, U.S. Navy P-3 aircraft have been operating from Kandahar in that role. Royal Australian Air Force AP-3C Orions operated out of Minhad Air Base in the UAE from 2003 until their withdrawal in November 2012. During the period 2008–2012, the AP-3C Orions conducted overland intelligence, surveillance and reconnaissance tasks in support of coalition troops throughout Afghanistan. The United States Geological Survey used the Orion to survey parts of southern and eastern Afghanistan for lithium, copper, and other mineral deposits. 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. One P-3, 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. It is based at Goddard Space Flight Center's Wallops Flight Facility, Virginia. Aero Union, Inc. operated eight secondhand 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. Several of these aircraft were involved in the U.S. Forest Service airtanker scandal but have not been involved in any catastrophic aircraft mishaps. Aero Union has since gone bankrupt, and their P-3s have been put up for auction.