Although many people might recall the U.S. withdrawal from the former Republic of Vietnam (RVN) as a chaotic mass evacuation of all American personnel and their closest South Vietnamese allies in the spring of 1975, in actuality the drawdown of U.S. military forces from Southeast Asia (SEA) had been completed two years earlier in Mar. 1973.

The passage of over 40 years, however, has muddled the nation's collective memory, confusing the earlier withdrawal of 542,400 American troops initiated by President Richard M. Nixon's "Vietnamization" policy in Jun. 1969 and completed by the ceasefire agreement signed by the United States and North Vietnam in Jan. 1973, with dramatic images of Operation Frequent Wind, the evacuation plan carried out in 1975 by the U.S. military as ordered by President Gerald R. Ford. The U.S. government transported about 7,000 American civilians and "at risk" South Vietnamese to waiting U.S. Navy (USN) ships offshore, while another 138,000 RVN nationals sought asylum with U.S. forces on their own.

The sight of the mass airlift of evacuees combined with the final turmoil at the U.S. embassy in Saigon and the swarm of South Vietnamese aircraft, bulging with people desperate to escape the fallen capital, flown out to the Seventh Fleet carriers and other smaller vessels has remained etched in the minds of many Americans, even those too young to have witnessed these events as they were unfolding.

Although not the only form of outward bound transportation used in the final months of the RVN collapse, at the center of this lasting visual memory are the helicopters that had already by the late 1960s become a symbol of the U.S. presence in SEA. Preserved in the nation's historical photographic record are the multiple landings and takeoffs by American aircraft throughout the hours of the "Night of the Helicopters," the landing of Vietnam Air Force (VNAF) helicopters on board USN ships, the ditching of others near the vessels, along with scenes of sailors pushing numerous South Vietnamese aircraft into the sea to clear overcrowded decks for additional landings.

Retrograde of Southeast Asia Aircraft (ROSAA)

Far less well known is the process by which the Department of Defense (DoD) retrograded the Army helicopters deployed to SEA. "The Vietnam retrograde was conducted while a high-intensity conflict was still in progress and, although a great deal of military equipment was evacuated to CONUS (i.e., the continental United States) or to other locations away from the theater, a substantial portion of materiel available in theater was left for the use and support of the South Vietnamese government after the withdrawal of U.S. forces."

Attendees at a Closed Loop Supply Conference held in Aug. 1971 discussed the difficulties associated with the withdrawal of Army aircraft from the RVN. Of major concern was the condition of the helicopters to be retrograded as well as how the equipment was to be moved. The process entailed much more than a simple reversal of the inbound transportation of new or recently overhauled aircraft originally deployed with units on USN aircraft carriers, Merchant Marine vessels, or flown in by the U.S. Air Force's (USAF's) Military Airlift Command (MAC).

Instead of the "preferred vessels"--the smaller naval aircraft carriers of the 1960s no longer in the USN fleet by the 1970s--desired by the Department of the Army (DA), logisticians had to rely more heavily on the Merchant Marine ships. Several of these marine transports were known as a Seatrain, considered by some to be "the first international intermodal carrier."

First developed in the 1920s as a "faster, more labor-efficient system for moving freight by water," according to Capt. James McNamara, former president of the National Cargo Bureau, the first Seatrain was able to carry 100 U.S. standard gauge railcars in which the cargo remained locked throughout the loading, voyage, and unloading stages of transport. The U.S. government took over operation of all five Seatrain ships during World War II, which were used extensively in the "transport of tanks and aircraft."

Additional ships were added to the Seatrain service after the vessels were returned to civilian control, but changes in the marine transportation industry in the 1960s gradually halted the carriage of railcars for commercial purposes. "By January 1970, the entire fleet was used for sealift to support the Vietnam War." The Seatrain vessels were also among the ships used to help evacuate tens of thousands of refugees from the RVN in the final months of the Vietnam conflict.

On Oct. 29, 1971, the first Seatrain left port in SEA with a load of retrograde aircraft. In December, large-scale shipments began with the major withdrawal of U.S. troops. The number of aircraft for return to CONUS reached a peak in Mar. 1972, then dwindled as the number of retrogrades were maximized and the intensification of combat resumed in mid-April of that year. Recognized at the time as a monumental undertaking, Project ROSAA involved the removal of 1,925 fixed and rotary wing aircraft from the U.S. Army Vietnam (USARV) air fleet. The majority of this materiel (1,226 or 64 percent) returned to CONUS, while the other 699 aircraft were dispersed to the VNAF, Korea, Hawaii, other allies, and in-country disposal.

Despite the substantial drawdown of troops and equipment from the RVN, the Army still had a large number of aircraft to be supported in SEA: 1,207 with the VNAF and another 74 scattered throughout the region, although most were in Thailand. In addition, aviation shop and tool sets as well as engines and transmissions had to be inventoried and shipped. The latter items encountered many delays before successfully being returned to CONUS.

The main problem with the engines and transmissions was the excess of spares as a result of reduced flying hours and associated damage. To get as much of that materiel out of RVN as quickly as possible, the Army adopted a "Stand-by Load" policy by which at least one readied load of engines or transmissions was placed in any available cargo space on a CONUS bound flight.

The situation with the return of shop and tool sets from in-theater was more complicated. When the sets finally arrived at the Red River Army Depot (RRAD), workers found that many of the items were in poor condition and had missing components. The DA policy which called for refurbishment before reissue of the returned sets involved the procurement of missing and unusable components. The resulting leadtimes delayed the rapid assembly of fully equipped sets and compounded the frustration of dealing with multiple demands and short supplies.

U.S. Army Aviation Systems Command (AVSCOM) Role in Operation ROSAA

While the USARV was responsible for determining which aircraft were to be retrograded, on Apr. 28, 1972, DA relieved the command of responsibility for returning U.S. Army Materiel Command (AMC) assets upon their arrival at the point of departure. This action relieved both USARV and the Continental Army Command (CONARC) of the tremendous transportation and maintenance burdens associated with the withdrawal. AMC and AVSCOM worked in cooperation with other services of the U.S. armed forces, American contractor personnel, and local workers in South Vietnam, Guam and the Philippines to assure the safe, efficient, and cost-effective return of aviation materiel.

For example, military and DA civilian employees with the Packing Division of the AVSCOM Directorate for Materiel Management were sent on a temporary duty assignment to the RVN in early 1973 to help pack and load a shipment of Army aircraft worth over $500 million. Their task was to "instruct and guide several hundred Vietnamese and U.S. Army and contractor personnel in the proper ways to preserve and protect an Army aircraft before sending it to sea. They were also responsible for checking all aircraft, once aboard ship, for secure tiedowns to prevent possible damage on the long ocean trip home."

Tasks on the AVSCOM team's long checklist included applying special procedures to preserve the engine and fuel cells; taking off and packing helicopter rotor blades; removing the wings from the U-8 Seminole fixed wing airplane; safeguarding Plexiglas with a paper barrier before spraying on a metal protectant against sea salt spray; securing light observation aircraft (such as the OH-6 Osage) into Sea Van containers; and bagging the large CH-47 Chinooks before tying them down on the ship's deck.

On Mar. 14, 1973, AVSCOM dispatched a team of five equipment specialists to SEA. They arrived in country just two days before all U.S. military activities in the RVN officially ended. Their job "was to relieve military men as contracting officer representatives with the American contractor who supported aircraft formerly operated by the 201st and 604th Army Aviation companies. These helicopters were to be used to fly out POWs (prisoners of war), if necessary, and fly the International Control Commission (ICC) and Joint Military Commission (JMC) whose job it was to attempt to police the fledgling cease-fire." In addition, the team helped to process the transfer of Army helicopters to the VNAF. Unlike earlier AVSCOM teams in the theater of operations, however, after the pull out of American forces, the group from St. Louis was left without any of the usual U.S. military support and had to live off the local economy for the duration of their 45-day assignment in Nha Trang, 250 miles north of Saigon.

AVSCOM logisticians also assisted with the recovery of the VNAF helicopters flown away hurriedly in the mass evacuation of Apr. 1975. About half of these aviation assets of the fallen republic's air force had to be dumped overboard, but USN aircraft carriers and other smaller vessels moved the remaining aircraft to Guam and the Philippines. According to an article in the Gateway Reporter of Apr. 9, 1976, "Following a cursory inspection, some high-level discussion, and a thorough debate on the subject of whose aircraft they were and who was to pay for their further travel, it was decided that they would indeed be returned to the U.S. to Corpus Christi Army Depot (CCAD) and AVSCOM would supervise their preparation for vessel shipment."

The Aviation Command dispatched two of its packaging specialists within days of receiving the mission. The DAC deployed to Guam inventoried the 49 helicopters assigned to him as well as supervised the aircraft's preservation for vessel shipment. The Apr. 9 newspaper account noted, "This included exterior and interior cleaning, rotor blade removal, defueling, general aircraft preservation, and application of exterior covers. All of this, of course, is meticulously covered in the shipping manuals; applying it in a foreign land under adverse conditions (e.g., sharp coral ground, 100 plus temperatures, 90 percent humidity, 14 hour days) is the trick, however." With the assistance of local workers and Army personnel from Hawaii, this group of recovered aircraft was ready for loading in 15 days. The other AVSCOM specialist sent to the Philippines, "using civilian technicians from … (CCAD, had his group of helicopters) prepared for shipment in 14 days. The difficulty came in fitting them below decks on the vessel."

The later recovery of these aviation assets along with the aircraft retrograded from the RVN before the cease fire of Jan. 1973, proved invaluable in the years immediately following the end of the Vietnam conflict. "Equipment evacuated from the theater and returned to the United States was gradually overhauled over the course of several years and ultimately used to minimize the effects of equipment procurement shortfalls that occurred during the lean budget years and military drawdown following the U.S. withdrawal from Southeast Asia."