Marines Had An “Aircraft Carrier On Land” With Catapults And Arresting Gear In Vietnam
Built from scratch, Chu Lai Air Base in South Vietnam was in the thick of exactly where tactical airpower was needed.
During the long conflict in Southeast Asia, U.S. Marines Corps jets regularly flew from bases on land in direct support of troops on the ground. However, only one of the airbases that the service operated from in South Vietnam was actually outfitted with arrester wires and even catapult launch gear. This was at Chu Lai, where the Marines built themselves what was basically a land-based “aircraft carrier” that was utilized by A-4 Skyhawk light attack jets and, later, F-4 Phantom II fighters.
The story of Chu Lai Air Base is inseparable from that of the A-4’s service during the Vietnam War, where it was, quite rightly, recognized as one of the signature aircraft of the conflict. U.S. Navy and Marine Corps Skyhawks bore a significant brunt of the air war for the first half of the conflict. In the process, pilots routinely flew into harm’s way on unglamorous missions, and the A-4 eventually accounted for more than a third of all Navy fixed-wing combat losses—Marine attrition rates were similar.
While Navy A-4s had been operating in Southeast Asia ever since 1964, when the Gulf of Tonkin incident led to more direct U.S. engagement in the conflict, Marine Skyhawks arrived later on the scene, as the ground war was becoming more intense. The Corps F-4 Phantom IIs, as well as RF-8 Crusader reconnaissance jets and EF-10 Skyknight electronic warfare aircraft, were already operating from Da Nang Air Base in South Vietnam when the service elected to throw its A-4s into the fray.
However, with Da Nang’s capacity to support additional aircraft increasingly stretched to the limit, the decision was made to set up a new airbase from scratch. This was Chu Lai, located on the coast, around 55 miles south of Da Nang. It would be a Marine-led effort that included the installation of a Short Airfield for Tactical Support (SATS) system, which would launch jets via a trackless catapult and recover them using aircraft carrier-style arresting gear. Unlike a catapult found on an aircraft carrier, which runs down a trackway recessed in the deck, the trackless version was based on a wheeled dolly and a cable-tow driven by a capstan, powered in turn by turbine engines.
The entire arrangement would enable aircraft to get into the air and land back at the base without the need for a lengthy, traditional runway. This would also help address the performance limitations that came from the hot and humid conditions. As well as extra capacity, the new base would bring airpower closer to where it was needed, reducing flying time to targets, as well.
Work on the land-based catapult as a part of the SATS system been launched more than 10 years previously, inspired at least in part by experiences in the Korea War, when pierced steel matting had been laid to form extemporized airstrips close to the troops. By the early 1960s, there were experimental SATS sites at Bogue Field, North Carolina, and Quantico, Virginia. At one stage it was planned for SATS to accept a range of carrier-capable naval aircraft, including the A-6 Intruder, F-4 Phantom II, F-8 Crusader, and even the ultimately abortive F-111B.
Testing the CE-2 trackless aircraft launcher as part of the SATS system at Quantico, in 1963:
However, Chu Lai seems to have been the only facility in which SATS was used operationally and the task of building the new base fell upon the Seabees, the Navy’s Construction Battalions. Working in temperatures of 100 degrees or more, the Seabees laid a runway made of AM-2 aluminum planks — roughly 1.4 million square feet in all — soon nicknamed “the tinfoil airstrip.”
By the end of May 1965, taxiways, a parking ramp, and arrester gear had also been built at Chu Lai. The catapult arrived sometime later. All this was constructed in an area that was not only unstable but also prone to becoming seriously waterlogged after heavy rain.
The basic SATS concept envisaged a rapidly established airfield with a runway that was 2,000 to 3,000 feet long and 72 feet wide. But since Chu Lai was expected to be in use for a considerably longer period than a typical expeditionary operation, and host many more aircraft, the design was adapted, with a planned length of 8,000 feet and width of 107 feet. Initially, however, only 4,000 feet was actually completed, while work continued to stabilize the ground below the other half. Thereafter, constant attention was required to keep the runway planking from sinking into the mud. Later on, Chu Lai also got its own conventional runway, located in parallel to the SATS airstrip.
The first jets to arrive at the base were the A-4Cs of Marine Attack Squadron 225 (VMA-225) and the improved A-4Es from VMA-311, both of which touched down on June 1, 1965. Missions began the same day. The E-model Skyhawk featured various improvements compared to the C variant, perhaps most important being five external hardpoints for stores instead of three, allowing a heavier load of weapons to be carried.
In Peter Mersky’s authoritative
US Navy and Marine Corps A-4 Skyhawk Units of the Vietnam War, former A-4 pilot retired Colonel Ned Carroll recalls what it was like to operate from the tinfoil airstrip in the early days:
Because of an engineering fluke, the bed material for the fabricated aluminum panel that made up the expeditionary runway had been laid over what we thought was laterite rock. However, once the monsoon arrived, we quickly learned that what we had presumed to be rock was actually clay! Softened by the heavy rains, the bedding material soon began to shoot out between the planks every time an aircraft passed over them. Deep voids quickly formed, which made takeoffs an adventure, with bumps so bad that eventually bombs were jarred loose and rolled down the runway! These bombs still had safening wires through their fuses, so there was no immediate danger of them exploding. Still, aircraft-bomb collision, with disastrous results, was always possible.”
Until the catapult arrived, A-4s were boosted into the air using rocket-assisted take-off (RATO) bottles. Each RATO bottle provided around 3,500 pounds of thrust for five seconds, approximately halving the takeoff run. Even so, the jets had to takeoff with a reduced fuel load, before quickly finding a KC-130 Hercules tanker to take on more gas.
Using the RATO gear was also not without its hazards, and pilots had to keep a close eye on the bottles to ensure both had fired properly. If not, and if carrying a heavy load, they would have to eject, since they would likely not make it off the runway.
Returning to Chu Lai was a case of lining up to catch the wire of the M-21 arrester gear, located around 1,000 feet further down the runway from the standard touchdown point and which could bring a Skyhawk to a standstill within as little as 250 feet. This was especially useful if the jet was returning to base in a damaged state, providing an extra degree of safety.
In the months that followed, Chu Lai’s Skyhawks saw heavy action, flying day and night in support of Marines and South Vietnamese troops sometimes engaged only half-a-dozen miles from the base perimeter. At times, Chu Lai itself came under attack from North Vietnamese forces, and the A-4s were required to defend their own base, which they did successfully.
Jets frequently returned to Chu Lai with significant combat damage, while poor weather led to a suspension of flying activity in late November 1965. By this time there were four Skyhawk squadrons at the base, with the addition of VMA-211 and VMA-214, and each unit had a complement of around 20 aircraft.
Ultimately, four squadrons of A-4s were considered the maximum that Chu Lai could accommodate, but different units were rotated in and out of the base as the demand for close air support continued to grow.
The catapult system finally became operational in May 1966 and was powered by a pair of General Electric J79 turbojets (as used in the F-4, among others), providing almost 35,000 horsepower. This could launch A-4s off the runway in either direction and, from a pilot’s perspective, reportedly made operations remarkably similar to flying to and from a real carrier deck. There was even a mirror landing aid to aid their recovery. Once up and running, the catapult could launch a fully armed Skyhawk into the air once every 90 seconds.
By the summer of 1966, the A-4 squadrons were reportedly averaging between 600 and 700 combat flying hours a month out of Chu Lai, with the close proximity of the fighting allowing pilots to fly multiple sorties each day. The rotational A-4 squadrons began “hot pad” alerts at the base, with a section of jets standing armed and ready to scramble, engines running and with pilots in the cockpits, should the need arise.
Much heavier and more powerful than the A-4, the Marine Corps F-4 was the other type to make extensive use of the SATS system in an operational capacity. During tests of the catapult, a Skyhawk was found to require 1,165 feet to take off, while a Phantom II needed 1,485 feet.
Armed with 12 500-pound bombs, an F-4B from VMFA-323 completed a first catapult shot from Chu Lai in August 1966, but it was not the smoothest start, as the pilot, retired Colonel Robert Jonhson, recalls in Peter E. Davies’
US Marine Corps F-4 Phantom II Units of the Vietnam War:
About halfway down the track, the aircraft seemed to lurch to a higher, nose-high attitude, and simultaneously with hitting the end of the catapult track, the starboard engine suffered a catastrophic failure (it exploded). My attention at this time was directed to my immediate front, which consisted of numerous trucks, Marines, and civilians waiting at a checkpoint off the end of the runway. Slowly climbing, I next noticed the base ammunition dump below my flight path. My briefing on emergency jettisoning of external stores did not cover this eventuality, but we were still flying… albeit only briefly.
I made a slight turn to the right in the direction of what appeared to be a clear area where we could jettison. As I tried to level the wings the stick bucked and froze in my hand. All I had to say was, ‘Eject, Jim, Eject.’ Jim responded instantly, and after hearing the second explosion, canopy and seat, I followed suit. Out altitude at the time was 100 feet or less. When my seat fired the aircraft was nearly 90 degrees to the horizon. As advertised, seat separation and chute opening occurred automatically, and I got a 90-degree swing in the chute before landing in a the-wire concertina fence. I looked up to see Jim come down in his chute about 30 yards away, The aircraft disintegrated about 50 yards beyond that, but none of the bombs detonated.
Colonel Johnson’s cool head saw him get a Distinguished Flying Cross and it was later found that the catapult shuttle had likely been incorrectly attached to the cable, leading to a near-deadly disaster.
In October 1966, the runway was extended to 10,000 feet and provided with a concrete surface, as well as parking ramps and taxiways. This made the airbase better suited to the Marine F-4s and the additional ramp space permitted three Phantom squadrons to be operated alongside the A-4s, although facilities on the ground remained basic, with most maintenance conducted in the open air.
Chu Lai survived the onslaught of the Tet Offensive that began in January 1968, during which the airstrip came under rocket attack, injuring two and damaging four Skyhawks. However, by September 1970, Chu Lai’s tenure as a Marine airbase had come to an end and it was handed over to the Army as the U.S. began withdrawing combat units. What became of the SATS system is unclear, but the Army would not have had any use for it. Thereafter, the remaining Marine combat squadrons in the country were concentrated at Da Nang. In fact, VMA-311 became the last U.S. combat squadron to leave Vietnam, which it did in January 1973, shortly before the ceasefire came into effect.
The “instant airfield” at Chu Lai was destined to be a one-off, but the lessons of SATS continue to this day, as the Marines continue to work on their Expeditionary Advanced Base Operations (EABO) concept, a modern approach to bringing tactical airpower to bear anywhere it might be needed. The 2019 Marine Corps Aviation Plan describes the EABO concept as follows:
“A future naval operational concept that mitigates peer competitors’ anti-access/area-denial capability by creating a more survivable, resilient, and persistent forward-postured force. The EABO concept is designed to re-establish the force credibility required to have a deterrent effect. Using key maritime terrain in the vicinity of close and confined seas, EABO provides decision-makers with sea denial options that are coercive, but not escalatory.”
Paralleling the way the A-4 and F-4 were adapted for land-based “cat and trap” operations, the Marines have been exploring the potential for the F-35C carrier-capable variant to undertake short-field and austere operations.
To prepare for real-world EABO scenarios, Marine F-35Cs have been using the M-31 expeditionary arresting gear, permitting operations from smaller runways. Moreover, within the U.S. military right now there is now an increasing focus on rapidly building up austere air bases. In particular, as the Pentagon continues its “pivot” toward the Pacific theater, there is an understanding that a conflict with China would likely see established infrastructure, including traditional airbases, quickly destroyed. In Europe, too, expeditionary base concepts are seen as vital for any conflict with any near-peer threat nation.
Meanwhile, although SATS was destined to be something of a footnote to the conflict in Vietnam, the effort to set up an airbase from scratch was indicative of the determined and innovative approach of the Marines in the air war in Southeast Asia.
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