His death was announced by Boeing Co., which acquired McDonnell Douglas in 1997. McDonnell's family told the St. Louis Post-Dispatch that he had been diagnosed with pancreatic cancer at Thanksgiving 2010 and died at his home in Clayton, Mo.
"The people of Boeing extend our deepest sympathies to the McDonnell family, and join them in mourning Sandy's passing," Boeing Chief Executive Jim McNerney said in a statement. "Sandy's commitment to his colleagues and customers, his country, and his community during his 40-year career and throughout his lifetime, was extraordinary."
Born in Little Rock, Ark., in 1922, McDonnell studied economics at Princeton University and also earned engineering degrees from the University of Colorado and Washington University in St Louis. He began his career as a technician during World War II for the then-top-secret Manhattan Project at Los Alamos, N.M., which developed the world's first atomic bomb.
After the war, he joined McDonnell Aircraft Corp., started by his uncle, James S. McDonnell. Over the years, he took on a number of jobs — including stress engineer, aerodynamicist and aircraft designer.
In 1955, McDonnell became group leader on the F-101 Voodoo, a supersonic fighter jet. By 1961, he was elected general manager for the F-4 Phantom fighter jet.
When McDonnell Aircraft and Douglas Aircraft Co. merged in 1967, he was elected director of the new company; and in 1972 he became chief executive.
During his tenure, the company won a contract to build the F/A-18 Hornet, which has been a fixture on U.S. Navy aircraft carriers since 1983 and is still in demand worldwide. Assembly lines for the plane's fuselage sections still hum in El Segundo. The company was also prime contractor for the nation's first orbiting laboratory, Skylab.
McDonnell, a 6-foot-2 former Boy Scout who served as national president of the Boy Scouts of America from 1984 to 1986, focused on ethics at McDonnell Douglas. His focus led to the development of the company's Code of Ethics, Philosophy and Five Keys to Self-Renewal program. McDonnell retired as chairman of the company in 1988.
In later years, he spent much of his time with charities, including CHARACTERplus, which teaches character-building to more than 300,000 students in the St. Louis area.
McDonnell and his wife, Priscilla, were married in 1946 and had two children.