Lockheed AC-130


The Lockheed AC-130 gunship is a heavily-armed ground-attack aircraft. The basic airframe is manufactured by Lockheed, and Boeing is responsible for the conversion into a gunship and for aircraft support. It is a variant of the C-130 Hercules transport plane. The AC-130A Gunship II superseded the AC-47 Gunship I in Vietnam.

The gunship's sole user is the United States Air Force, which uses AC-130H Spectre and AC-130U Spooky variants. The AC-130 is powered by four turboprops and has an armament ranging from 20 mm Gatling guns to 105 mm howitzers. It has a standard crew of twelve or thirteen airmen, including five officers (two pilots, a navigator, an electronic warfare officer and a fire control officer) and enlisted personnel (flight engineer, electronics operators and aerial gunners).

The US Air Force uses the AC-130 gunships for close air support, air interdiction, and force protection. Close air support roles include supporting ground troops, escorting convoys, and flying urban operations. Air interdiction missions are conducted against planned targets and targets of opportunity. Force protection missions include defending air bases and other facilities. Stationed at Hurlburt Field in Northwest Florida, the gunship squadrons are part of the Air Force Special Operations Command (AFSOC), a component of United States Special Operations Command (SOCOM).

Development
The C-130 Hercules was selected to replace the AC-47 Spooky Gunship I used during the Vietnam War, to improve gunship endurance capabilities and increase capacity to carry munitions.

In 1967, JC-130A USAF 54-1626 was selected for conversion into the prototype AC-130A gunship. The modifications were done that year at Wright-Patterson Air Force Base, by the Aeronautical Systems Division. A direct view night vision telescope was installed in the forward door, an early forward looking infrared (FLIR) in the forward part of the left wheel well, and Gatling guns fixed mounted facing down and aft along the left side. The analog fire control computer prototype was handcrafted by RAF Wing Commander Tom Pinkerton at the USAF Avionics Laboratory. Flight testing of the prototype was subsequently performed primarily at Eglin Air Force Base, followed by further testing and modifications. By September 1967, the aircraft was certified ready for combat testing and was flown to Nha Trang Air Base, South Vietnam for a 90 day test program. The AC-130 was later supplemented by the AC-119 Shadow Gunship III, which later proved underpowered.

Seven more aircraft were converted to the "Plain Jane" configuration like the AC-130 prototype in 1968, and one aircraft received the "Surprise Package" equipment the next year. In 1970, an additional 10 AC-130As were acquired under the "Pave Pronto" project. Conversion of C-130Es into AC-130Es for the "PAVE Spectre" project followed.

Regardless of their project names, the aircraft were more commonly referred to by the Squadron's call sign: Spectre.

Recent and planned upgrades
In 2007, AFSOC initiated a program to upgrade the armament of existing AC-130s still in service. The test program planned for the 25 mm GAU-12/U and 40 mm Bofors cannon on the AC-130U gunships to be replaced with two 30 mm Mk 44 Bushmaster II cannons. In 2007, the Air Force modified four AC-130U gunships as test platforms for the Bushmasters. However, AFSOC canceled its plans to install the new cannons on its fleet of AC-130Us. It has since removed the guns and re-installed the original 40 mm cannons and returned the planes to combat duties. Brig. Gen. Bradley A. Heithold, AFSOC's director of plans, programs, requirements and assessments, said on 11 August 2008 that the effort was canceled due to problems with the Bushmaster's accuracy "at the altitude we were employing it" in tests. There were also schedule considerations that drove the decision, he said.

There are also plans to possibly replace the M102 howitzer with a breech-loading 120 mm mortar, and to give the AC-130 a standoff capability using either the AGM-114 Hellfire missile, the Advanced Precision Kill Weapon System (based on the Hydra 70 rocket), or the Viper Strike glide bomb.

Design
These heavily-armed aircraft incorporate side-firing weapons integrated with sophisticated sensors, navigation and fire control systems to provide precision firepower or area-saturation fire with its varied armament. The AC-130 can spend long periods flying over their target area at night and in adverse weather. The sensor suite consists of a television sensor, infrared sensor, and radar. These sensors allow the gunship to visually or electronically identify friendly ground forces and targets in most weather conditions.

The AC-130U is equipped with the AN/APQ-180, a synthetic aperture radar for long-range target detection and identification. The gunship's navigational devices include inertial navigation systems and a Global Positioning System. The AC-130U employs technologies developed in the 1990s and can attack two targets simultaneously. It also has twice the munitions capacity of the AC-130H. Although the AC-130U conducts some operations in daylight, majority of its combat missions are conducted at night.

During the Vietnam era the various AC-130 versions following the Pave Pronto modifications were equipped with a magnetic anomaly detector (MAD) system called the Black Crow (AN/ASD-5), a highly sensitive passive device with a phased-array antenna located in the left-front nose radome that could pick up localized deviations in earth's magnetic field and is normally used to detect submerged submarines. The Black Crow system on the AC-130A/E/H could accurately detect the unshielded ignition coils of Soviet trucks driven by the North Vietnamese that were hidden under the dense foliage of the jungle canopy along the Ho Chi Minh trail. It could also detect the signal from a hand-held transmitter that was used by air controllers on the ground to identify and locate specific target types. The system was slaved into the targeting computer.

PGM-38/U 25 mm ammunition for AC-130U
The PGM-38/U Enhanced 25 mm High Explosive Incendiary (HEI) round was created to expand the AC-130U gunships' mission in standoff range and survivability for its 25 mm GAU-12/U gun system. This round a combination of the existing PGU-25 HEI and a M758 fuse designated as FMU-151/B to meet the MIL-STD-1316. The FMU-151 has an improved arming delay with multi-sensitive range.

Operational history
The AC-130 Gunship first arrived in South Vietnam on 21 September 1967 under the Gunship II program, and began combat operations over Laos and South Vietnam that year. By 30 October 1968, enough AC-130 Gunship IIs arrived to form a squadron, the 16th Special Operations Squadron (SOS) of the 8th Tactical Fighter Wing (TFW), at Ubon Royal Thai Air Force Base, Thailand.

By December 1968 most AC-130s were flown under F-4 Phantom II escort from the 479th Tactical Fighter Squadron, normally three Phantoms per Gunship. In late 1969, under the code name of "Surprise Package", 56-0490 arrived with solid state laser illuminated low light level TV with a companion YAG laser designator, an improved forward looking infrared (FLIR) sensor, video recording for TV and FLIR, an inertial navigation system, and a prototype digital fire control computer. Surprise Package was equipped with the latest 20 mm Gatling guns and 40 mm Bofors cannon, but no 7.62 mm close support armament. Surprise Package was refitted with upgraded similar equipment in the summer of 1970, and then redeployed to Ubon RTAFB. Surprise Package served as a test bed for the avionic systems and armament for the AC-130E. In the summer of 1971, Surprise Package was converted to the Pave Pronto configuration, and assumed its new nickname, Thor.

In Vietnam, gunships destroyed more than 10,000 trucks and participated in many crucial close air support missions. During the Invasion of Grenada (Operation Urgent Fury) in 1983, AC-130s suppressed enemy air defense systems and attacked ground forces enabling the successful assault of the Point Salines Airfield via airdrop and air land of friendly forces. The AC-130 aircrew earned the Lieutenant General William H. Tunner Award for the mission. AC-130s also had a primary role during the United States invasion of Panama (Operation Just Cause) in 1989 when they destroyed Panama Defense Force headquarters and numerous command and control facilities. Aircrews earned the Mackay Trophy for the most meritorious flight of the year and the Tunner Award for their efforts.

During Operation Desert Storm, AC-130s provided close air support and force protection (air base defense) for ground forces, and battlefield interdiction. The primary interdiction targets were early warning/ground control intercept (EW/GCI) sites along the southern border of Iraq. The first gunship to enter the Battle of Khafji helped stop a southbound Iraqi armored column on 29 January 1991. One day later, three more gunships provided further aid to Marines participating in the operation. The gunships attacked Iraqi positions and columns moving south to reinforce their positions north of the city. Despite the threat of surface-to-air missiles (SAMs) and increasing visibility during the early morning hours of 31 January 1991, one AC-130H, AF Serial No. 69-6567, call sign Spirit 03, opted to stay to continue to protect the Marines. A SAM subsequently shot down Spirit 03, and all fourteen crew members perished.

The military has used AC-130 gunships during Operations Restore Hope and United Shield in Somalia, in the NATO mission in Bosnia-Herzegovina, and in the 1997 evacuation of American noncombatants in Albania.

The AC-130 gunship has the distinction of holding the record for the longest sustained flight by a C-130. From 22nd through the 24th of October 1997, two AC-130U gunships flew 36.0 hours nonstop from Hurlburt Field, Florida to Taegu Air Base (Daegu), South Korea while being refueled seven times in the air by KC-135 Stratotanker aircraft. This record flight shattered the previous record longest flight by over 10 hours while the two gunships took on 410,000 lb (186,000 kg) of fuel. Gunships also were part of the buildup of U.S. forces in 1998 to convince Iraq to comply with UN weapons inspections. The United States later used gunships during the 2001 invasion of Afghanistan, and the Iraq War. In 2007 US Special Operations forces used the AC-130 in attacks on suspected al-Qaeda militants in Somalia. The AC-130 has the distinction of never having a base under its protection lost to the enemy.

Current aircraft
The AC-130H has a unit cost of US$132.4 million, and the AC-130U a unit cost of US$190 million (fiscal 2001 constant dollars). Currently there are eight AC-130H and seventeen AC-130U aircraft in active duty service.


 

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