The plane, an Aero Commander Model 500-B, broke up in the air and was destroyed after crashing about 80 miles south of Burns, Ore., witnesses told authorities.
Vessels was flying the plane, which was bound from Redding, Calif., to Montana, Harney County Sheriff Dave Glerup told the Associated Press on Thursday.
A passenger, Sam Cannell, 73, of Anderson, Calif., also was killed. The National Transportation Safety Board and the Federal Aviation Administration are investigating the crash.
Vessels was the owner of Vessels Stallion Farm, his family's commercial breeding operation in Bonsall in northern San Diego County. He was a past president of the American Quarter Horse Assn. and the California Thoroughbred Breeders Assn. and a member of the quarter horse group's hall of fame.
The family business began in 1951, when Frank Vessels Sr. founded Los Alamitos Race Course on his sprawling ranch in Cypress, where he bred quarter horses in addition to racing them.
His grandson, Frank Vessels III, was born a year later and as a youth became a farm hand in the stock yards at the track.
"They gave me a shovel and told me to go to work," Scoop Vessels told The Times in 1997. "The nickname stuck."
Vessels' mother, Millie, managed the track for many years. After she sold the track to Hollywood Park for $58 million in 1984, the Vessels family moved its base to Bonsall. Vessels took over the business when his mother died in 1992.
Since the early '80s, Vessels had been in Bonsall running the San Luis Rey Downs Training Center for thoroughbreds as well as a golf course. The Vessels Stallion Farm today is a premier breeding enterprise boasting such outstanding sires as First Down Dash, which won the quarter horse world championship in 1987, and the leading thoroughbred In Excess.
Before taking over the family's horse breeding enterprise, Vessels excelled in a different form of racing — off-road trucks. He competed in the Baja 500 and Baja 1000 desert races among others, was voted the sport's rookie of the year in 1974 and in the late '70s won a string of off-road class championships.
Vessels also was among a small group of Southern California truck driver-owners who persuaded NASCAR to add a truck division to its stock-car racing series.
He is survived by his wife of 18 years, Bonnie; and three sons, Bryan, Colt and Kash.