Lockheed AC-130A of the 16th Special Operations Squadron, 8th Tactical Fighter Wing at Ubon Royal Thai Air Force Base in March 1969. Note: Ubon RTAFB was the forward operating location for the 16th SOS home-based at Nha Trang Air Base, South Vietnam. (U.S. Air Force photo)
The second combat evaluation of the prototype AC-130A Gunship II successfully concluded on May 14, 1968. Exactly one month later, on June 14, Gen. Momyer, Commander of the 7th Air Force, ordered the prototype AC-130A to begin flying operational missions out of Tan Son Nhut Air Base, South Vietnam. The aircraft was primarily used for interdiction of truck traffic along the Ho Chi Minh trail and sampan (boat) traffic on primary waterways including the Mekong River. The third phase of the Tet Offensive was anticipated and destroying enemy supplies was critical.
In the meantime, seven JC-130As were converted to the AC-130A configuration. The aircraft were outfitted with the same basic equipment as the prototype: four 20mm Vulcan cannons, four 7.62mm miniguns, LORAN D navigation system, forward looking infrared system, Beacon Tracking Radar, Night Observation Device, fire control system with an analog fire control computer, semiautomatic flare launcher, and 20-kilowatt illuminator with visible and infrared modes.
The initial conversions were completed by late 1968, and the first three AC-130As arrived in Southeast Asia to begin combat operations. The 16th Special Operations Squadron was initially organized under the 8th Tactical Fighter Wing at Nha Trang Air Base, South Vietnam, and forward deployed to Ubon Royal Thai Air Force Base. The 16th SOS was used to interdict enemy truck traffic moving through the Barrel Roll, Commando Hunt and Steel Tiger areas (Plain of Jars, central and southern panhandle) of Laos. The AC-130A was very effective in a variety of missions and there were more requests for sorties than could be supported with the limited number of aircraft available. Consequently, a hierarchy of mission priorities was established. The highest priority was given to sorties for armed reconnaissance and night interdiction of enemy truck and sampan traffic. Priority two missions were for night interdiction of targets which were bombed and then hit by a fire suppression mission. Next was close air support of U.S. (and friendly) ground forces, installations, outposts, hamlets, forts and towns. Priority four sorties were for support of combat search and rescue missions. Fifth Priority went to supporting Troops In Contact (TIC) using the sophisticated offset firing system. Offset firing involved receiving a signal from a ground beacon set-up by friendly ground troops and feeding enemy distance and direction information into the on-board fire control computer to attack the enemy position based on the offset from the ground beacon. Most (direct fire) TIC missions were supported by AC-47D "Spooky", AC-119G Shadow and AC-119-K Stinger gunships. However, in situations were offset firing was required, the AC-130A was far superior to the AC-119K (the AC-47D and AC-119G were not capable of offset firing). Priority six missions were for armed escort of friendly truck convoys and ship convoys during daytime. The last priority was for general interdiction and harassment missions against targets of opportunity.
The prototype AC-130A returned to the United States in March 1969 for further modifications. This left just three AC-130As at Ubon RTAFB; however, during the first quarter of 1969 (January to March), the four AC-130A compiled an impressive combat record -- 245 missions were scheduled (fragged) and only 30 were aborted for an 88 percent reliability rate. One thousand eight hundred fifty-three trucks were sighted and roughly one-third were destroyed and another one-sixth damaged. Eleven boats were destroyed out of the 23 sighted. Thirteen TIC missions were flown.
Antiaircraft Artillery (AAA) continued to be the most serious threat to the AC-130A. The first loss of an AC-130A (A/C 54-1629) happened on May 24, 1969. The gunship was hit and significantly damaged by two 37mm AAA rounds. The aircraft crashed and burned after attempting an emergency landing at Ubon RTAFB. Two crew members were killed.
To protect the gunships and allow for continued use in moderate to high AAA threat areas, new combat tactics were developed. The AC-130A was escorted by an F-4 Phantom II equipped to deal with AAA gun positions. After the F-4 eliminated or suppressed the Flak, the gunship would attack enemy supply vehicles. To counter these tactics, the enemy increased the number of AAA positions along the supply routes (Ho Chi Minh Trail); however, the F-4s were usually able to successfully eliminate the AAA threat long enough for the AC-130A to complete its mission.
The National Museum of the United States Air Force has an AC-130A (S/N 54-1630) on display in its Cold War Gallery.
Prototype AC-130 gunship
"Plain Jane" initial conversion
TECHNICAL NOTES: Armament: Four 7.62mm mini-guns and four 20mm cannons Engines: Four Allison T-56-A-11 turboprops of 4,050 hp Attack speed: 145 knots Cruising speed: 180 knots Duration: 3-5 hours for a typical combat mission (6 hours maximum with 30 minutes reserve fuel) Attack altitude: 3,500 ft. for TIC missions (offset firing), 5,000 ft. for night interdiction with minimal AAA threat; 6,500 or 8,000 ft. in areas with moderate to heavy AAA Span: 132 ft. 7 in. Length: 97 ft. 10 in. Height: 38 ft. 6 in. Weight: 124,200 lbs. maximum Crew: 11 (pilot, co-pilot, navigator, fire direction officer, night observation device operator, radar sensor operator, flight engineer, loadmaster, master armorer, 7.62mm minigun gunner/armorer and 20mm cannon gunner/armorer) Serial numbers: (Prototype) 54-1626; (Initial conversions [from JC-130A]): 53-3129, 54-1623, 54-1625, 54-1627 to 54-1630 (S/N 54-1629 crashed on May 24, 1969) Other notes: Initial AC-130As were dubbed "Plain Jane" after the more sophisticated "Surprise Package," "Pave Pronto" and later variants were introduced.