The U.S. Air Force has special prefixes for all its weapons. For example GAU stands for “Gun Automatic Unit” and are basically machine-guns used by aircraft. Most fire 20mm-30mm shells from multiple rotating barrels to achieve very high (50 a second or more) rates of fire. The smallest caliber GAU weapons are 7.62mm and 12.7mm machine-guns. But now there is a new GAU weapon, the GAU-5A, which will be installed in over 2,000 combat aircraft. Sounds normal enough, but it isn’t. GAU-5A is a single-barrel 5.56mm semi-automatic weapon. Actually GAI-5A is a lightweight version of the M-4 assault rifle that is standard with most American troops. One big difference from the M-4 is that GAU-5A does not have full-automatic fire capability. It is meant for single shots or, at best, automatic three-round bursts.
The GAU-5A is a lightweight rifle that, when disassembled, fits into the Aces II ejection seat survival kit. The GAU-5A is a basically a smaller version of the M-4 assault rifle using commercially available components to create a rifle with the M-4 receiver but shorter adjustable stock and barrel. All these components, when broken down, fit into the standard 406x356x89mm (16x14x3.5 inch) 18.2 kg (40 pound) survival kit that comes with each Aces II ejection seat found in A-10, F-15, F-16 and F-22 fighters as well as B-1 and B-2 bombers. The survival kit normally contains no weapons, except for perhaps a knife. The only weapon the pilot usually (and still) has is a 9mm pistol carried in a holster.
The GAU-5A weighs less than 3.2 kg (seven pounds) and assembles in less than a minute, or 30 seconds with some practice. The air force is buying 2,136 GAU-5As for survival kits of pilots operating over territory containing Islamic terrorists. This is welcome news to the pilots, because the few downed pilots who have been captured by Islamic terrorists have usually been executed in grisly fashion like beheading or burned alive.
Downed pilots already have pilot recovery teams standing by that can reach the downed pilot quickly but often not quickly enough. The GAU-5A, which comes with four standard 30 round M-16/4 magazines can fire single shots or three round bursts. It has basic iron sights so, even with practice, is only accurate out to 200-300 meters. Some air forces have equipped their pilots with similar, but bulkier weapons. Russia provides an AK-74 carbine (the smallest version of this standard AK type assault rifle) while others have included 9mm machineguns.
The GAU-5A does not require modification of the ejection seat to accommodate a larger and bulkier weapon and is similar enough to the standard M-16/4, which all pilots learn to use in basic training, to be used effectively without much additional training. Many of the first pilots to receive the GAU-5As in their survival kits took them to the rifle range to practice assembling and firing them. The weapon was found to perform as advertised and proved to be a morale boost for pilots operating over particularly dangerous territory. A pilot with a GAU-5A can hold off, or perhaps even drive off, armed attackers and provide time for another fighter to use its targeting pod and laser guided missiles to find any other attackers and kill or discourage them with missiles or cannon fire. Many fighter-bombers operating over Islamic terrorist territory now carry the smaller APKWS 70mm guided missiles. These weigh 13.6 kg (30 pounds) with a 2.7 kg (six pound) warhead and a range of about six kilometers. Four or more can be carried in place of one larger smart bomb. APKWS is also carried on helicopters. These missiles are preferable to the larger (45 kg) Hellfire because the smaller warhead allows the APKWS to be fired on armed enemies who have gotten very close to the downed pilot. The survival kit includes a small radio that enables communications with nearby aircraft.
The survival kits also contain long range satellite location transponders, flares, flotation devices, emergency food items, some water and so on. Staying within the standard weight of the survival kit is important because the effectiveness of the ejection seat depends on the seat, with all its contents (like the pilot) being within certain weight limits.