Development of the AC-130 begun with a requirement in the Vietnam War, where an aircraft with more enhanced ground-attack capabilities was needed. The C-130 Hercules was chosen to be the aircraft the next gunship is based on. The "Gunship II" called program begun with a JC-130, built for conversion into the first AC-130 prototype, which was equipped with four M61 Vulcan 20mm Gatling Guns and Minigun Machine Guns. The sensors it used were a night vision telescope, forward looking infrared (FLIR) installed in the forward part of the left wheel and a laser distance ladder. Testing in Vietnam was very successful, so that seven additional JC-130 were converted into AC-130 and those had more advanced avionics and electronics than the first aircraft. In 1968 they were stationed at the 16th Special Operation Squadron.
During the program "Project Surprise Package“ a C-130A was converted into an AC-130 with different armament in comparison to the conventional AC-130. The two Vulcan Gatlings on the aircraft´s tail were removed and replaced by two Bofors 40 mm guns. And the electronics were greatly enhanced. And after the "Pave Ponto“ program nine additional C-130A were converted like on the "Project Surprise Package“. The resulting AC-130 is equipped with two Miniguns, two M61 Vulcan Gatlings and two Bofors 40 mm guns. The avionics were supplemented by the ASD-5; a Magnetic anomaly detector, an AAD-7 forward looking infrared sensor, an AVQ-7 searchlight and the APQ-150 Beacon tracking radar.
The heavy armed aircraft that were used in Vietnam, were only the eleven AC-130E built during the "Pave Spectre" program, while on the new Gunships (69-6567 to 69-6577) the two Bofors 40 mm guns were removed and replaced by a 105 mm Howitzer cannons. The aircraft entered service in 1971 and showed to be very useful. They were called AC-130H Spectre and they were equiped with the new Allison-T56-A-15-engines.The Spectre was first used in 1989 in Panama during Operation Just Cause and during the Second Gulf War in 1991. In the Battle of Khafji a Spectre was downed by Iraqi Air Defenses, because it was used in daylight, where it was not designed for. That was the only known loss of an AC-130 Gunship.
The AC-130U Spooky was built in the 1990s, making it a very modern gunship. It is equipped with the radar of the F-15E Strike Eagle, a 25 mm Gatling gun, a Bofors 40 mm gun and a 105 mm Howitzer cannon. The highly advanced avionic allow it to hit even moving ground targets easely. This derivative was used during Operation Enduring Freedom in Afghanistan, to perform close air support. In January 2007, a Spooky attacked probable terrorists in the south Somalian village Badel, where many people got killed. During Air Strike missions against the dictator Muammar al-Gaddafi, Spookys were used as well.
The thermographic camera of the AC-130 is able to track targets on day and night and at all weather conditions.
The latest AC-130 variants are equipped with lasers.