Kirby Grant, who entertained millions as the star of the popular Sky King radio and television series, was killed in a traffic accident near Titusville Tuesday as he drove to view the launch of the space shuttle at Kennedy Space Center.

Mr. Grant, 73, was pronounced dead on arrival at Jess Parrish Memorial Hospital in Titusville less than an hour after the 8 a.m. accident on State Road 50 about four miles west of Titusville, Florida Highway Patrol Capt. Mike Kirby said.

Mr. Grant of 6038 Sheoah Blvd., Winter Springs, was driving in traffic on the two-lane road when he attempted to pass another automobile. The car pulled into his path and Mr. Grant swerved across the road and into a ditch to avoid it, Kirby said.

The impact flung Mr. Grant from the car into about three feet of standing water. A passing motorist, Roy Walters of Orlando, pulled the former televison hero out “almost immediately,” but he could not be revived, Kirby said.

Kirby said state troopers have no information on the other vehicle involved in the accident and that an investigation is continuing. Mr. Grant was alone in his car.

An autopsy will be performed to determine the cause of death, he said.

Arnold Richmond, chief of visitor services at the space center, said Mr. Grant had been invited by a friend to watch the shuttle launch from the VIP stands.

Mr. Grant starred in Sky King from 1951 to 1954, and the show appeared in reruns from 1959 to 1966. He played the lead role of Sky King, a good man who wore a cowboy hat, always did right and traveled about in a twin-engine airplane called Songbird. The show originated on radio, on which it was heard from 1946 to 1954, with a different set of actors supplying the voices.

Born Kirby Grant Hoon Jr. in Butte, Mont., on Nov. 24, 1911, Grant first made his acting reputation in film in the late 1930s.

Before playing Sky King, he played leads in low-budget Westerns and other action pictures, often as a Canadian Mountie in such movies as Trail of The Yukon, Call of the Klondike, Northwest Territory, Yukon Gold and Northern Patrol.

Mr. Grant was educated at the University of Washington in Seattle, Whitman College in Walla Walla, Wash., and the American Conservatory of Music. He was considered a child prodigy as a violinist. Also an accomplished singer, Mr. Grant was a radio and supper club entertainer before entering films.

Mr. Grant and his wife, Carolyn, moved to Florida in 1971. “I fell in love with the place,” he said.

A popular guest speaker with civic and business groups, he once told a group of businessmen he “didn’t go looking for Hollywood,” but was transferred to California by NBC radio. At the time, he was a staff singer with the network in Chicago.

Mr. Grant tried repeatedly but unsuccessfully for several years to revive the television series that made him famous. He dreamed of shooting a new Sky King series in Florida and often spoke enthusiastically of using Kennedy Space Center and Embry-Riddle Aeronautical University in Daytona Beach as story locations.

A revival, however, never came about.

In 1976, he started the Sky King Youth Ranch for troubled teen-age boys. But the state forced the Seminole County ranch to close in July 1977 after it ran into financial problems.

Mr. Grant had a severe heart attack in 1978. He recovered after three bypass operations and the insertion of a special valve in his heart.

In 1979, he became goodwill ambassador at Sea World and remained in the position until August 1985, when he took a similar position at Cypress Gardens.

Co-workers at both locations said they were shocked by Mr. Grant’s death and spoke fondly of him as a man who always smiled and retained a youthful vigor.

“You would see people in their 30s go up to Kirby and say, ‘I’m a pilot because of you,’ ” said Sea World spokeswoman Kim Devos.

Mr. Grant is survived by his wife, daughters, Kendra and Kristin, and son, Kirby III.