USAF AC-119 Gunships
By Col Norbert Simon, USAF Ret., Commander, 56 Special Operations Wing, 1972

“There are many heroes in wartime. Some heroes rate more notice than others. But in my mind the heroes of the Stinger squadron need take a back seat to no one.”

One of the more frustrating aspects of the Vietnam War was the inability of our Air Force to engage the enemy during hours of darkness. In the early and middle stages of the war the enemy was able to move men and supplies at night via the extensive road networks almost with impunity. The Air Force attempted to use parachute flares dropped from aircraft to illuminate stretches of the main supply routes. The objective was to spot vehicles moving along the trails, and attack them with fighter or bomber aircraft.

From personal experience I can attest that trying to dive bomb a truck at night by the light of flares is tough business indeed. A high degree of skill combined with luck is required. Hitting a truck or other vehicle during daylight hours is difficult but at night other factors are introduced that make it nearly impossible. The “art” of dive-bombing requires maximum use of the pilot’s visual senses. Dive angles, tracking time, correct azimuth control are all important elements of dive bombing that are complicated to an extreme degree when daylight is eliminated. Perhaps the greatest problem associated with night dive-bombing is the inducement of vertigo. The light of the flare cast against cloudbanks or haze layers created artificial horizons that could confuse the pilot sufficiently for him to lose control of the aircraft. We lost many pilots during night strikes. Nearly one-third of all F-4 pilots lost were at night although at least eighty per cent of F-4 flights were conducted during daylight hours.

Other aircraft such as the Martin B-57 bomber and the A-1 aircraft were utilized at night and were more successful than the F-4. One other aircraft, the A-26 was based at NKP prior to my arrival, and formed into a squadron called the Nimrods. The A-26 was the same aircraft used in few numbers at the end of WWII and extensively in Korea. Aircraft remaining from those two conflicts were overhauled completely and modified to a great extent for the Vietnam theater of operations. Records indicate the Nimrods were one of the most effective truck killing squadrons in SEA, but diminishing aircraft numbers forced their retirement from the scene. No doubt aircraft such as the B-57, A-1 and the A-26 did a great job of interdicting and destroying trucks; at least the total claims added up to some fantastic numbers. However it was obvious to intelligence sources that despite the number of reported kills vast amounts of supplies were reaching South Vietnam via extensive networks.

In an effort to stem the flow of war materiel at night the Air force modified two cargo aircraft, the C-119 and the C-130, in order that they could be used for the night interdiction mission. This chapter deals with the C-119, re – designated the AC-119K (for attack) and which was stationed at NKP. I am not in a position to know why the Air Force decided to take an underpowered, obsolete aircraft and modify it almost to the point of disbelief. The answer must be that the Air Force used the C-119 not because it wanted to but because the Congress would not approve the purchase of a new aircraft for a specialized purpose.

In order to be fitted for its night attack role the C-119 had to be modified drastically. Many of the design characteristics originated by the Fairchild Aircraft Corporation of Long Island, New York were clearly outstanding. The large fuselage had swing open rear doors that afforded the easy ingress and exit of large bulky items of cargo. The high-winged aircraft was equipped with two Curtis­Wright radial turbo compound engines that provided ample power under normal circumstances. However, in the event of the loss of one engine under maximum load conditions the aircraft could not maintain a selected altitude. This deficiency could be extremely hazardous to the health of crewmembers especially when an engine failed on takeoff or in mountainous areas. I often thought the C-119 would have been a superb cargo aircraft if four smaller engines such as the Pratt and Whitney R-2800 had been designed for the aircraft by Mr. Fairchild thereby giving it an ample reserve of power in case of engine failure.

The Air Force decided the best way to correct the C-119’s lack of single engine performance was to add two jet engines, one each outboard of the piston engines. Fairchild Corporation undoubtedly wishes they had those 2,000 pounds thrust jet engines available when the aircraft was designed. Although the jet engines were relatively small they added the extra margin of power even at maximum takeoff gross weights and thus they were used primarily for the safety they offered during takeoffs and landings.

For attack firepower the AC-119Ks cargo interior was modified to contain two M-61 20MM Vulcan rapid -fire canons rigidly mounted on pedestals and with muzzles pointed out the side fuselage windows. The M-61 was designed by the General Electric Corporation of America and can be considered a plus for American weapons technology. Each gun had the capability of firing 6,000 rounds per minute of either high explosive incendiary (HEI) or armor piercing incendiary (API) ammunition. In addition to the M-61s the AC-119K also carried four smaller miniguns firing the standard 7.62MM NATO ball ammunition. All six guns were fixed rigidly and extended from the side of the fuselage at a 30-degree down angle. Although the guns had a tremendous rate of fire the obvious limiting factor was weight and space requirements to house the thousands of rounds of ammunition. Weight considerations reduced continuous firing to about three minutes per gun. The guns were never fired, however, at continuous rates lasting more than 15 seconds. Although three minutes firing duration and 15 second burst may sound small, in reality only a very short burst was required to destroy a target if the pilot was on the mark. Short bursts also added immeasurably to gun life.

Control of gun firing and aiming of the gun sight was the responsibility of the aircraft commander who sat in the left seat of the pilot’s compartment. He was aided by a co-pilot who sat in the right seat. Also seated up front with the pilots were the flight engineer who monitored all the engine instruments and two navigators who operated the specialized navigation equipment. In the cargo or fuselage section of the aircraft other crewmembers attended to the operation of the guns, flare launcher, Illuminator and Night observation scope (NOS), also known as the starlight scope. Just aft of the pilot’s compartment and forward of the guns was an opening in the fuselage formerly occupied by the left forward cargo door entrance. The door was entirely removed and in its place was mounted a unique device called the Starlight Scope. The scope was nothing more than a night telescope which magnified particles of light thousands of times. Under ideal conditions, i.e., no clouds, dust or haze, the landscape was revealed in an almost daylight-like quality. However, ideal conditions were not often found over the jungles of Laos and Vietnam. Nevertheless as the proficiency of the Starlight Scope operator increased he could distinguish objects on the ground with a fairly high degree of reliability.

At the navigator station was an infra-red detection system that was designed for locating heat emitting sources on the ground. Since trucks and other motor vehicles produce large amounts of heat the system in theory was an ideal method of locating trucks in the dark. Unfortunately the system could not distinguish between the heat emitted by trucks and that emitted by bonfires or other heat emissions on the ground. Because of this fact the system was not used extensively. In the rear of the AC-119 was mounted a large searchlight (the illuminator) which was rarely used over enemy territory.

During a typical combat mission the AC-119 carried a crew of ten. These ten included the aircraft commander, co-pilot, two navigators, flight engineer, Starlight Scope operator (NOS), three gunners and an illuminator operator (IO). The IO and one of the gunners acted as scanners for antiaircraft fire. The IO also launched the flares and ground markers the gunship carried.

The essence of a successful mission was complete cooperation and coordination among crewmembers. When flying the AC-119 everything was accomplished by the book, using detailed check lists which covered every detail of equipment operation. The aircraft commander, or pilot in command, in accordance with Air Force tradition acted as captain or skipper of the aircraft regardless of his rank relative to other crewmembers. For instance it was not uncommon to have the aircraft commander junior in rank to one or both of the navigators. This fact notwithstanding the aircraft commander was directly responsible for the success or failure of the mission.

Describing the technique employed by AC-119K crews is relatively simple. It hardly needs to be said that the tactics of hitting an enemy target were entirely different from that of a tactical fighter aircraft. Firing from the left side fuselage of an aircraft was probably not a first with the AC-119K; however, concentrating fire power onto a single target under cover of darkness was no doubt originated by the Air Force during the Vietnam War.

Truck hunting in a free fire area such as the Plains Des Jarres in northwest Laos was considered the simplest operation by Stinger crews. A free fire area meant that anything moving on the ground was fair game with no danger of firing on friendly forces. Command and control and rules of engagement problems were minimal thus alleviating mental strain on the crew. Arriving over the target area, all ten pairs of eyes searched the ground for signs of vehicle movement. Experiences proved that the AC-119K could slip through the night sky and surprise the enemy driving with lights on unaware of impending attack. When a vehicle was sighted the aircraft commander maneuvered the aircraft into firing position. Using a gun sight reticle superimposed on the pilot’s compartment left window, the aircraft commander placed the gun sight on the target and attempted to hold it there by using the correct variables of altitude, airspeed, angle of bank and slant range. Because the aircraft commander was unable to concentrate on his flight instruments during the sighting process, the copilot made fine adjustments as necessary to keep the aircraft in correct relationship with the target. When the aircraft commander estimated that he was tracking the target correctly he squeezed the gun trigger on his control column. At this instant all hell, seemingly, broke loose inside the aircraft. It should be noted that even when the guns were not firing the noise level was deafening induced by the roar of two big engines and blasts of air screaming through the windowless gun ports and door less front fuselage. The addition of four miniguns firing at the rate of 6,000 rounds per minute each created an added racket and vibration that brought pain to eardrums covered by helmets. Each seventh round in ammo belts were sprayed with a special chemical that produced the well-known tracer effect. Viewed from either the air or the ground the hail of red tracers was frightening, looking very much as hundreds of lightning bolts striking the ground simultaneously.

Until the advent of the Russian-made heat seeking ground to air missile designated the SAM- 7, and named the “Strella”, the Stingers could fly rather safely at their best gun firing attitude of between three and five thousand feet. Stinger personnel soon found it was not practical for the AC-119K to operate at altitudes required to outstrip the Strella’s capability. This would have meant flying at heights above ground level of over 9,000 feet. The dispersion factor of the guns and sensor limitations precluded such a course of action. Instead the AC-119Ks were fitted with a countermeasure that proved quite effective in negating the Strella threat. The aircraft was already equipped with a flare launcher as part of its overall night capability. These flares were standard magnesium type with an intense brilliance of over 50,000 candlepower and which also emitted tremendous amounts of infrared energy. The flare’s fall was retarded by quick opening parachutes and both the parachute and flare illumination had a high degree of reliability. In order to increase reliability close to 100 per cent an additional flare launcher was installed in the rear fuselage in place of the useless searchlight. During night operations over enemy territory two scanners were stationed at the rear of the aircraft to visually search for the tell-tale rocket stream denoting launch of a Strella missile. At the first indication of a Strella launch it was the scanner’s duty to instantly warn the crew and simultaneously launch a series of flares. The pilot’s action was to immediately place the aircraft into a tight turn to help evade the missile’s tracking. At the same time it was expected that the Strella would lock on to one of the flares and explode harmlessly in the air. The Strella proved to be a deadly threat to slow moving propeller driven aircraft. Prior to the introduction of countermeasures two AC-130 aircraft were downed in Laos killing all on board. Two A-1 tactical aircraft, an OV-10 Forward Air Control aircraft and a Jolly Green rescue helicopter were all downed by Strella fire within the space of a few hours. Additionally, one AC-119K was downed near An Loc in South Vietnam. (Editor’s Note: while Strellas were fired at AC-119ks, Stinger 41 was downed by AAA at An Loc).

As it turned out, the flare countermeasure for the AC-119K proved to be a morale and confidence builder for the Stinger crews after the flares were proved to be effective during several Strella attacks. Certainly if the AC-119s had been forced out of operation, the lives of the people around Saigon and DaNang would have been in considerably more danger from close-in enemy mortar and rocket attacks.

The sensors of the AC-119K were especially suited for ferreting out enemy night troop activity. The enemy could not afford to mass troops in sufficient quantity to make an all-out attack on either Saigon or DaNang. Every time this was attempted at night his troops were decimated by the horrendous firepower of 20MM explosive and incendiary ammunition.

The Stinger squadron possessed eighteen AC-119K aircraft based at Nakhon Phenom (NKP), which was the main operating and maintenance base. Three aircraft were deployed to the large Air Force and Marine base at DaNang, RVN, in the northern I Corp region of South Vietnam. Another three were located at Bien Hoa Airbase near Saigon for perimeter defense of the base and city.

Aircraft flying out of NKP were used primarily for night truck hunting in northern and central Laos. Each type of mission had its peculiar method of operation, and element of danger. The risks were higher flying over the flak infested main supply routes in Laos, with mountainous terrain and stormy weather as added danger and difficulty factors. Flying perimeter defense around Saigon and DaNang also presented special problems. Because friendly troops, villages, and vehicles were so directly involved, precise navigation and positive certainty of the target were absolute requirements.

As commander of the 56 Special Operations Wing I had two opportunities to fly combat missions with the Stingers. The first was a mission originating out of NKP which was to be a search for enemy vehicles on the legendary Plaines Des Jarres area of Northwest Laos. As I had no other duty on board other than observer I felt the best thing I could do was to stay well out of the way and be quiet. Having spent almost all my flying time in fighter type aircraft I was very impressed by the professionalism of the Stinger crew with its constant demand of coordination of duties. As it turned out the mission itself was rather uneventful. For instance, Strella missiles did not attack us, but you can bet I did my share of searching the ground for possible launches. We did account for several vehicles, and as I indicated previously their destruction by 20MM gunfire was awesome indeed. I later flew a perimeter defense mission out of Bien Hoa. We were in constant communication with US Army ground liaison officers who apprised of us of possible enemy movement. We did fire on several suspected enemy locations but otherwise the mission was uneventful. But as I indicated previously, the enemy did not dare mass troops for a concentrated attack on Saigon. In fact there was never an attempt to do so during the tenure of the AC-119s in the night sky of Saigon. After my first-hand experience flying with the Stingers I can attest that it would have been the wrong thing for the enemy to do.

In perspective, the AC-119 and AC-130 were the right weapon systems at the right place and time. In the case of the AC-119 I believe the results were accidental and not in the minds of the original planners. I feel sure that if Defense Department authorities had their way they would have opted for an entirely new weapon system, and not a converted cargo plane. Regardless, by accident or design, the AC-119 filled a vital need in the short time it was operational. Because of advancements in radars and surface to air missiles, the AC-119 or other aircraft like it will have to be utilized most judiciously.

To the crews that flew her, the AC-119K will remain a legendary aircraft, and in the annals of history the AC-119 may well rate with other oddities as the Merrimac and Monitor or perhaps the barrage balloon. One fact is certain, the AC-119Ks and AC-119Ks will be symbolized in the minds of a generation of North Vietnamese and Viet Cong as the sound of thunder, lightning and destruction from the sky. One final note. There are many heroes in wartime. Some heroes rate more notice than others. But in my mind the heroes of the Stinger squadron need take a back seat to no one.

Letter from Colonel Norbert Simon

Editor’s Note: Col Simon’s Story and letter were documented and provided by Bill Petrie (Stinger IO, original Association Webmaster, CMSgt, Ret)