The aircraft uses video images, infra-red and radar sensors to locate targets at day and night. Its computers are designed to follow two targets with two different sensors and fire two different guns at the same time.
Former crew members say that, in practice, the guns are never fired simultaneously, partly because of ammunition considerations.
The aircraft has more than a dozen crew: Pilot, co-pilot, navigator, fire control officer, electronic warfare officer, flight engineer, operators for its TV camera and infra-red detection set, a loadmaster, and four or five "gunners" - who reload the weapons which are normally controlled from the flight deck.
Although regarded as a highly successful machine - used most recently in support of operations in Panama, Grenada, the Gulf War, Bosnia and Afghanistan - its slowness and typical low operating altitude make it vulnerable to ground fire.
It does have a system that drops chaff and flares to counter radar and infra-red guided missiles. There are also heat shields under the engines to try to mask them from heat-seeking missiles.
Even so, one AC-130 was shot down in Iraq in 1991 by a surface-to-air missile. The other recent loss was in Somalia when, it is thought, a round exploded in one of the plane's cannons.
There are over 20 types of AC-130 on "active duty", according to the US Air Force.