新山一空軍基地
美軍使用情形 > 第315空中突擊聯隊 > 牧工行動

The 315th ACG was responsible for Operation Ranch Hand Defoliant operations missions. South Vietnamese president Ngo Dinh Diem requested USAF help to remove enemy cover. The USAF's Special Aerial Spray Flight was already using C-123s in the U.S. to control mosquitoes. After some modifications to the aircraft (which included adding armor for the crew), C-123B Provider aircraft arrived in Southeast Asia in January 1962 under the code name "Ranch Hand".
Flying specially-equipped C-123 Providers, members of the squadron flew low and slow to reduce the risks to our soldiers on the ground and to expose the enemy.  Ranch Hand never had more than five C-123Bs. Sometimes these aircraft had their spray equipment removed to conduct regular airlift flights, and it appeared that the defoliation mission might be eliminated altogether. With the increased U.S. commitment in South Vietnam in 1964 and 1965, however, requests for defoliation soared.
Ranch Hand grew into an essential part of the war effort, with over six million acres sprayed in South Vietnam between 1965 and 1969. Beginning in 1965 with only four aircraft, by the middle of 1969 Ranch Hand had about 25 UC-123 aircraft available for missions.  On 15 October 1966, Ranch Hand became the mission of the 12th Air Commando Squadron.
In 1965 Ranch Hand began using a very effective defoliant called Agent Orange, and the range of targets grew considerably.  The Agent Orange controversy later became both a political and veterans' issue. Operation Sherwood Forest sprayed the key Viet Cong-controlled Boi Loi Woods northwest of Saigon, and Operation Swamp Fox targeted the mangrove forests used by the communist for shelter in the Mekong Delta. Late in the year, operations extended into the Ho Chi Minh Trail in Laos. A flood of defoliation requests came in, and the small number of crews flew constantly.
The defoliation of vital enemy strongholds, transportation routes, and crops forced the communists to vigorously defend against the spraying. Ranch Hand aircraft regularly received damage on missions—considering their low altitude, low speed and large size, they were easy to hit. Ranch Hand maintainers worked constantly to repair the damage and get their UC-123s ready for the next mission. In addition to engines and flight controls shot out, and several crewmen wounded and killed, Ranch Hand lost five UC-123s in combat between 1966 and 1968.
In February 1967, Ranch Hand was ordered for the first time to fly missions over the De-Militarized Zone (DMZ) separating North and South Vietnam. These missions helped uncover infiltration routes from the north and expose stockpiles of supplies hidden in the DMZ. By June, 1967, the number of UC-123s had increased to 20.
During the Tet Offensive in early 1968, spraying operations were temporarily halted in favor of airlift missions. Between Feb. 5 and March 20, Ranch Hand UC-123s flew 2,866 airlift sorties.
The 315th ACW was transferred to Phan Rang Air Base on 14 June 1967.  With the Vietnamization drawdown in 1969, Ranch Hand was reduced from 25 to 13 aircraft. In 1970 Agent Orange was discontinued, and the existing stocks of Agent White ran out in May 1970. After the last anti-crop mission in January 1971, anti-mosquito spraying continued for a short time after, and then Ranch Hand ended.