The U.S. Air Force is equipping its four engine AC-130 gunships with more powerful sensors and missiles that enable these four-engine propeller driven aircraft to fly high enough (6,500 meters/20,000 feet) to avoid ground fire and operate during the day. This is a major change in the way these gunships have long operated. These gunships are owned by SOCOM (Special Operations Command) although they support all combat troops, not just the Special Forces and SEALs. While SOCOM operators prefer to operate at night, they are often out during daylight, when the presence of a gunship overhead can be a real lifesaver. This use of missiles, instead of cannon, is a recent development and the success of this technique has changed the basic design of these gunships and how they are used.
The current AC-130H gunship (nicknamed Spooky) is a 69 ton, four engine aircraft originally armed with two 20mm machine-guns, a 40mm autocannon, and a 105mm howitzer. While the aircraft can stay in the air for six hours (or more, if it refuels in the air), what really makes a difference is how well the weapons operate. Flying low (often under 10,000 feet) and at night, the gunship relies on night vision devices and well trained gunners to take out targets that are giving the troops on the ground a hard time. Four decades of continuous improvements have made the gunships increasingly lethal. But the troops have found that missiles can be just as effective as cannon fire and the AC-130 can launch missiles from higher altitudes (beyond the range of enemy anti-aircraft guns or missiles).
The recently ordered AC-130J gunships will be equipped with more powerful sensors, armed with a single 30mm autocannon, and multiple launchers for Viper Strike and SDB glide bombs, as well as Hellfire and Griffin guided missiles. Viper Strike is a 90cm (36 inch) long unpowered glider. The 130mm diameter (with the wings folded) weapon weighs 20 kg (44 pounds). Because the Viper Strike comes straight down, it is better suited for urban warfare. Its warhead weighs only 1.8 kg (four pounds) and less than half of that is explosives. This means less damage to nearby civilians but still powerful and accurate enough to destroy its target. A laser designator makes the Viper Strike accurate enough to hit an automobile or a foxhole.
The Griffin is a 15.6 kg (34.5 pound) guided missile with a 5.9 kg (13 pound) warhead which is larger than that carried by the larger (47 kg) Hellfire missile. To achieve this Griffin has a shorter range (4 kilometers), which is adequate for a gunship, which is designed to go after targets just below it, not far away.
Hellfire weighs 48.2 kg (106 pounds), carries a 9 kg (20 pound) warhead, and has a range of 8,000 meters. The 130 kg (285 pound) Small Diameter Bomb (SDB, also known as the GBU-39/B) has a shape which is more like that of a missile than a bomb (nearly two meters, as in 70 inches, long and 190mm in diameter), with the guidance system built in. The smaller blast from the SDB resulted in fewer civilian casualties. The SDB carries only 17 kg (38 pounds) of explosives and can be dropped from high altitude, using laser guidance to hit very small targets below.
Existing gunships are using all these missiles already. Equipping existing gunships to carry and fire all these missiles is neither difficult nor expensive. U.S. SOCOM (Special Operations Command) has also adopted a U.S. Marine Corps idea to provide an "instant gunship" system, which enables weapons and sensors to be quickly rolled into a C-130 transport and hooked up. This takes a few hours and turns the C-130 into a gunship armed with a 30mm autocannon and Viper Strike and Griffin missiles.
Because of their vulnerability to ground fire, the AC-130s have long only operated at night. The last time an AC-130 was lost was at Khafji, Saudi Arabia during the 1991 Persian Gulf War. The aircraft was leaving the combat zone at sunrise and was visible to Iraqi gunners in the area. But in the last two years, more and more AC-130s have been out in daylight, flying high enough to avoid hostile fire and using their powerful sensors to get a close look at what’s down there and use their missiles on anything that looks hostile.