The Lockheed P-3 Orion is a four-engined, turboprop anti-submarine and maritime surveillance aircraft developed for the United States Navy and introduced in the 1960s.

While based on the same design philosophy as the Electra, the aircraft differed structurally; it had 7 feet (2.1 m) less fuselage forward of the wings with an opening bomb bay, and a more pointed nose radome, a distinctive tail "stinger" for detection of submarines by MAD, wing hardpoints, and other internal, external, and airframe-production technique enhancements.

[citation needed] The Orion has four Allison T56 turboprops, which give it a top speed of 411 knots (761 km/h; 473 mph) comparable to the fastest propeller fighters, or even to slow high-bypass turbofan jets such as the Fairchild Republic A-10 Thunderbolt II or the Lockheed S-3 Viking.

Similar patrol aircraft include the Soviet Ilyushin Il-38, the French Breguet Atlantique and the British jet-powered Hawker Siddeley Nimrod (based on the de Havilland Comet).

In the early 2000s, the paint scheme changed to its current overall gloss gray finish with the original full-sized color markings.

[5] In 1963, the U.S. Navy's Bureau of Naval Weapons contracted Univac Defense Systems Division of Sperry Rand to engineer, build, and test a digital computer (a device then in its infancy) to interface with the many sensors and newly developing display units of the P-3 Orion.

Univac delivered the CP-823/U to the Naval Air Development Center at Johnsville, Pennsylvania, in 1965; this directly led to the production computers later equipped on the P-3C.

[2][10][11] Lockheed Martin opened a new P-3 wing production-line in 2008 as part of its Service Life Extension Program (ASLEP) for delivery in 2010.

A complete ASLEP replaces the outer wings, center-wing lower section, and horizontal stabilizers with newly built parts.

[12] In the 1990s, the U.S. Navy attempted to procure a successor aircraft to the P-3, and selected the improved P-7 over a naval-specific variant of the twin turbofan-powered Boeing 757, but this program was subsequently cancelled.

Additional underwing stations, or pylons, can carry other armament configurations, including the AGM-84 Harpoon, AGM-84E SLAM, AGM-84H/K SLAM-ER, AGM-65 Maverick, 127 millimetres (5.0 in) Zuni rockets, and various other sea mines, missiles, and gravity bombs.

In fiscal year 1995, the U.S. Navy planned to reduce active-duty patrol squadrons from sixteen to thirteen—seven on the East Coast, six on the West.

[citation needed] Versions were developed for the National Oceanic and Atmospheric Administration (NOAA) for research and hurricane hunting/hurricane wall busting, for the U.S. Customs Service (now U.S. Customs and Border Protection) for drug interdiction and aerial surveillance mission with a rotodome adapted from the Grumman E-2 Hawkeye or an AN/APG-66 radar adapted from the General Dynamics F-16 Fighting Falcon, and for NASA for research and development.

[needs update] One additional active duty fleet reconnaissance squadron (VQ-1) operates the EP-3 Aries signals intelligence (SIGINT) variant at Naval Air Station Whidbey Island, Washington.

Having only joined the operational Fleet earlier that year, this event marked the first employment of the P-3 in a real world "heightened threat" situation.

[citation needed] Beginning in 1964, forward deployed P-3s began flying various missions under Operation Market Time from bases in the Philippines and Vietnam.

The primary focus of these coastal patrols was to stem the supply of materials to the Viet Cong by sea, although several of these missions also became overland "feet dry" sorties.

Originally attributed to a low altitude mishap, later conjecture is that this aircraft may have also fallen victim to anti-aircraft artillery (AAA) fire from the same source as the April incident.

[24] Within hours of the coalition air campaign's start, "Outlaw Hunter" detected a large number of Iraqi patrol boats and naval vessels attempting to move from Basra and Umm Qasr to Iranian waters.

"Outlaw Hunter" vectored in strike elements which attacked the flotilla near Bubiyan Island, destroying 11 vessels and damaging scores more.

[24] Several days before the 7 January 1991 commencement of Operation Desert Storm, a P-3C equipped with an APS-137 Inverse Synthetic Aperture Radar (ISAR) conducted coastal surveillance along Iraq and Kuwait to provide pre-strike reconnaissance on enemy military installations.

[3] Although the P-3 is a MPA, armament and sensor upgrades in the Anti-surface Warfare Improvement Program (AIP)[25] have made it suitable for sustained combat air support over land.

[29] Several U.S. Navy P-3Cs, and two Canadian CP-140 Auroras, a variant of the Orion, participated in maritime surveillance missions over Libyan waters in the framework of enforcement of the 2011 no-fly zone over Libya.

Following the Iranian Revolution in 1979, the Orions continued in service, after the IIAF was renamed the Islamic Republic of Iran Air Force (IRIAF).

After the crash of one with the loss of an entire crew, the type was grounded; nonetheless, the aircraft were maintained in an armed state and airworthy condition throughout the escalation period of 2001 and 2002.

[39] In April 2011, the Portuguese Air Force also contributed to Operation Ocean Shield by sending a P-3C[40] which had early success when on its fifth mission detected a pirate whaler with two attack skiffs.

Aero Union, Inc. operated eight secondhand P-3As 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.

A few notable examples are: United States Pahlavi Iran Netherlands New Zealand Norway Portugal Spain Thailand For Canadian aircraft on display, see Lockheed CP-140 Aurora.