South Viet Nam: Above the Battle

Scanning from the left seat, Pilot Pat Evans spotted a brilliant flash on a hilltop 7,900 feet below. A pair of fighter planes wheeled in, tossing bombs into the jungle. Then a string of helicopters settled to earth and squads of infantrymen leaped from them, firing as they ran. Evans shrugged. "They are fighting like hell down there," he said, "and for us it is business as usual."

It may be business as usual for any one of the 40 other pilots of Saigon-based Continental Air Services, but the business itself is most unusual. CAS, a subsidiary of the U.S.'s...