The assumption in the 1960s was that the use of herbicides in Vietnam did not pose a significant danger.
The UC-123K tactical transport known as “Patches” got its name the hard way. The aircraft was held together nose to tail with repairs to the battle damage inflicted by almost 600 hits from enemy ground gunners in Vietnam.
When its flying days were over, Patches was retired to the US Air Force Museum in Dayton, Ohio, as a memorial to the airmen who flew the dangerous “Ranch Hand” missions from 1962 to 1970.
Ranch Hand used herbicides to defoliate the vegetation in Vietnam, where the jungle provided concealment and cover for Viet Cong insurgents. It began as a peripheral notion in 1961 on a White House list of “techniques and gadgets” that might be tried in lieu of all-out combat and expanded from there.
At its peak in 1969, Ranch Hand employed only 25 spray planes, but the results and consequences went far beyond anything the White House ever imagined. Local commanders and ground forces swore by Ranch Hand, which stripped bare the enemy ambushes and hiding places. It was part of a broader operation named “Trail Dust,” which included spraying from backpacks, trucks, and riverboats, but the main operation was Ranch Hand.
The propeller-driven C-123 had long since been declared obsolescent but it found new purpose in Vietnam. In 1968, auxiliary jet engines were mounted under the wings, making takeoffs less hazardous for the heavily loaded Ranch Hand aircraft. The enhanced model was designated UC-123K.
The spraying was done from treetop level and was especially risky with the original equipment, which dispensed no more than one-and-a-half gallons of herbicide per acre, half the amount necessary for defoliation. Before the Ranch Hand crews got better sprayers that pumped three gallons an acre, they had to fly a second mission against each target. The ground gunners knew this and were waiting for them. With the improved system it took four minutes to empty the 1,000-gallon tank and cover an area 16 kilometers (10 miles) long and 80 meters (260 feet) wide.
About 10 percent of the Ranch Hand sorties destroyed crops supporting the Viet Cong—a priority for the South Vietnamese government—but the vast majority of them were flown to expose the enemy’s strongholds and travel routes. Even critics of the program concede that this saved many thousands of American and allied lives.