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Note: This article first appeared in the booklet "Air Commando! 1950-1975: Twenty-five Years at the Tip of the Spear". The original illustrations and some footnotes from the original article are omitted here. Illustrations are from the Image Archive which includes some new AC-130A pictures are courtesy of Bill Madsen.


AC-130s Prowl the Ho Chi Minh Trail

by: Col Michael E. Haas, USAF, Retired

Spectre: (spek’ter), n. 1. a spirit of a terrifying nature.
2. some object or source of terror or dread.

From its very first combat field evaluations in Southeast Asia in 1967-8, the C-130A "Gunship II" alerted both Air Force and Army commanders they were on to something special; something far beyond mere replacement of the wornout AC-47 and AC- 119 Gunships.

Despite their usefulness in armed reconnaissance missions, theater commanders saw both the AC-47 and its immediate successor, the AC-119, as most effective in defending isolated Vietnamese and Army Special Forces camps. In this role the AC-47 and AC-119s were defending allied troops from trouble. The Gunship II was to conduct a far more predatory mission, something that sent the huge Gunship actually looking for trouble.

So heavily armed that during early development stages it was initially designated Project "Gunboat," the C-130A could hardly be considered anything but a predator. Compared to the three miniguns on the AC-47, or the four found on AC-119 Shadow, the Gunship II boasted four miniguns and four 20mm cannon. Later models added 40mm Bofors and a modified Army 105mm field howitzer, the largest gun ever placed in an aircraft. And that was just the armament. (click here for some Gunship drawings)

The Gunship's advanced electronic sensors stripped the night away from the enemy as had never been done before. The Night Observation Device (NOD) was an image light intensifier that magnified moon and star light to provide a clear view of ground activity to the NOD operator on all but the darkest nights. Another night device was the Forward Looking Infrared (FLIR) system, a sensor that picked up heat emissions from both the human body and vehicle motors regardless of light conditions.

The prototype C-130 Gunship II began its first combat evaluation in late 1967. Flying armed reconnaissance over both Laos and Vietnam, the testbed Gunship was an instant success, especially as a truck killer. Air Force Major General William G. Moore, Air Force Deputy Chief of Staff, Research and Development, concluded the C-130A Gunship "far exceeded fighter type kill ratios on enemy trucks and other equipment." A still bigger compliment came from the senior "customer" in Vietnam, Army General William Westmoreland, so impressed he proved very reluctant to let the testbed aircraft leave the country even for a much-needed overhaul!

With an all-out effort expediting completion of the modification/overhaul, the testbed C-130A returned earlier than planned to Southeast Asia in February 1968. And just as promptly proceeded to repeat its spectacular early successes. By November 1,000 trucks had been sighted, of which 228 were destroyed and a further 133 damaged; of thirty-two sampans sighted, nine were destroyed and eight more damaged."' The prototype was even sent to the Demilitarized Zone separating North and South Vietnam, in search of North Vietnamese helicopters."'

A lengthy, follow-on USAF analysis divided the total financial costs of the prototype by the total number of "major events" (e.g. trucks/boats destroyed, secondary explosions caused, gunsites destroyed). The findings concluded "the Gunship II prototype to be one of the most cost effective, close support interdiction systems in the U.S. Air Force inventory."'

What had started out as a search for a follow-on aircraft to the AC-47, had now grown into an extremely complex, mixed Gunship fleet operating in Vietnam, Thailand and Laos. By the end of 1968, the Air Force had four AC-130As (now using the radio callsign "Spectre"), operating from Thailand, as well as a mixed AC-47 and AC-119G/K fleet operating in the other countries mentioned. It would not be until the early 1970s that the Air Force Gunship fleet would be streamlined to only one type.

Gunships of every type were active around the clock during the communists' 1968 Tet Offensive.(1) This included the Gunships IIs which were deployed to Tan Son Nhut Air Base near Saigon. During this period the Gunships were organized into the 16th Special Operations Squadron, and the C-130 Gunship II was re-designated the "AC-130A". In November of the same year, the 16th "Spectres" moved to Ubon, Royal Thai Air Force Base (RTAFB), arriving with 44 officers and 96 airmen."'

The Thailand-based 16th continued to rack up high kill-ratios including, on May 8, 1969, a very unusual target. Flying over Laos in the early morning darkness a Spectre NOD operator spotted a slow moving object flying low-level toward a rectangular opening in the jungle. Ground reports of enemy helicopter sightings had been received before, but this was the first time one had actually been detected by an armed U.S. aircraft.

On this night the Gunship crew moved quickly to secure permission to attack, then put several 20min cannon bursts into the clearing, hitting the helicopter directly and causing numerous secondary explosions nearby." Unconfirmed accounts from Gunship crews stationed at Ubon at that time report the 16th crew spared no effort in describing their achievement (ad nauseam!) to the co-located fighter pilots unfortunate enough to be in the bar that night.

The fortunes of war swing both ways, and it was only two weeks after the helicopter shootdown that the inevitable happened to the Spectres. On May 24th enemy anti-aircraft fire from sites along the Ho Chi Minh Trail mortally wounded (2) the first AC-130A, killing one crewman immediately, and a second as the aircraft crash landed and burst into flames at its home base. The majority of the crew bailed out over Thailand, to be successfully recovered later. Nor were all the dangers to the 16th SOS found only over the Trail. Only two months after the shootdown, a communist sapper attack against Ubon RTAFB itself found the Gunships in their first perimeter defense battle.

The closing days of 1968 saw a vicious circle of combat becoming even more so over attempts to interdict the Ho Chi Minh Trail. The more the Air Force and Navy determined to cut the vital logistics lifeline, the more anti-aircraft defenses the North placed on the trail. The Air Force decided to up the ante once again, this time with a new tactic.

In December 1968, a 7th Air Force study concluded that Gunships escorted by fighters could probably kill more trucks than could Gunships attacking alone. Results from the first test of this tactic came quickly. On the combined Gunship/Fighter team's first night mission, escorting F-4D(3) fighters destroyed or silenced two 37mm sites firing on the Gunship. It was a winning combination, even though some areas remained too hot even for fighter-escorted Spectres.

With or without fighter escort, the Gunship remained firmly in the center of this dangerous air-ground brawl over "ownership" of Trail. In January, 1969, four Spectres with relatively inexperienced crews accounted for 28 percent of the truck kills along the Trail" Two months later, the 16th accounted for more than 44 percent of all truck kills in a thirty-day period, despite flying only 3.7 percent of the allied interdiction sorties.

During the same period (4) however, North Vietnam increased its anti-aircraft defense of the Trail by 400 percent. The Trail was fast becoming a bloody example of the football cliche describing an "irresistible force meeting an immovable object" (5) And it was about to become even more lethal ... for both "teams".

In February 1972, the first 16th SOS Spectre was equipped with a 105mm howitzer that would destroy anything on the Trail from a safer standoff distance than what the crews had enjoyed to date. This time the North Vietnamese upped the ante; bigtime. That same month two Spectres were downed by enemy fire, one to a telephone pole-sized, surface to air missile (SA-2) on March 29th. On May 5th North Vietnamese gunners fired five, heat-seeking SA-7s at an AC-130 (6), the first time the shoulder mounted, missile had been encountered by Spectre Crews.

During this period alone (7), allied aircraft destroyed or damaged 10,609 trucks in the Laotian panhandle. USAF statistics confirm that the top three truck killers, in descending order, were the AC-130, AC-119 and F-4 fighter." And this was "just" Laos! In Vietnam Spectres beat back the attackers from the Ben Het Ranger Camp and on May 5th (the same day another Spectre was hit by the SA-7), another Gunship helped repel enemy infantry and tanks already into the defensive barbed wire of the Polei Kleng compound.

Fighting over the Trail continued to escalate, even as America's direct involvement in Vietnam began to wind down through President Nixon's "Vietnamization" program. By 1973 the AC-1l9s had been turned over to the Vietnamese Air Force and USAF Gunship efforts centered on the 16th SOS at Ubon. With a fourteen man crew on each AC-130, the 16th had become the single largest USAF combat squadron in Southeast Asia". The last Spectre combat mission in Southeast Asia was flown over Cambodia on 15 August, 1973." Over the years six of the big Spectres had gone down in combat, taking with them fifty-two crewmen.

As difficult as it is to conduct "cost vs. benefit" analyses where the loss of human life is concerned, the combat reality is that losses to the premier truck killer on the Ho Chi Minh Trail were far below those predicted by detractors of the Gunship concept. Nor did the end of American involvement in Southeast Asia spell the end of the Gunship era.

The 16th SOS redeployed to the United States in December, 1975, with the "H" model AC-130s moving to Hurlburt Field, Florida, home of the 1st Special Operations Wing. The "A" models were sent to the Air Force Reserve 711th SOS at nearby Duke Field, home station for the 919 Special Operations Group. Five more years would elapse before an American disaster in the Iranian desert brought renewed Pentagon interest in their unique capabilities.

Look at some Gunships in the C-130 Image Archive

Author's notes:

(1) Beginning January 30th, the first day of the Vietnamese New Year, the communists attacked 36 of 45 provincial capitols, and destroyed nearly 400 U.S. and Vietnamese aircraft on the ground. Although a tremendous psychological victory for the communists, particularly in the U.S. television media, it cost the enemy massive battlefield casualties. Included in the bloodbath was the virtual annihilation of the Viet Cong, North Vietnam's surrogate forces in the south. back

(2) Returning to home base with its hydraulic system shot away, the aircraft began a nearly uncontrollable climb. Only the aircraft commander's (Lt Col Schwehm) order to bring all surviving crew members to the AC-130's flight deck brought the aircraft's nose down to a controllable situation. back

(3) These fighters came from the 497th Tactical Fighter Squadron ("Night Owls"). back

(4) November, 1968 to May, 1970 back

(5) Evidence that the North Vietnamese were indeed hurting came from prisoner interrogations and road watch team reports that on occasion the truck drivers were actually chained to the inside of their vehicle cab to keep them from abandoning their truck in the event of an air attack. back

(6) One of the missiles hit the aircraft's tail section, but the Spectre was able to land safely. At that time the AC-130s had no ready countermeasure to the heat-seeking missiles; decoy flares would come later. back

(7) November, 1971 to March, 1972. back

The author, Col. Michael E. Haas, has a book available from the Government Printing Office entitled, Apollo's Warriors: United States Air Force Special operations During the Cold War Stock No.:008-070-00726-6, cost $28. I have a copy and found it very interesting. It covers quite a few different missions and has some previously unpublished photos.

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