John Walton, a member of the Wal-Mart board of directors and the second son of company founder Sam Walton, was killed in a plane crash Monday in Wyoming, according to media reports.

The company reportedly said Walton died when the ultralight aircraft he was piloting crashed shortly after taking off from the Jackson Hole Airport in Grand Teton National Park. Walton, 58, was the aircraft’s only occupant.

Walton joined the Wal-Mart board in 1992. Forbes magazine had listed Walton as the 11th-richest person in the world with a net worth of more than $18 billion.

He was also a board member of the Walton Family Foundation. He served in the U.S. Army Green Berets as a medic during the Vietnam War, where he was awarded the Silver Star, the company said.

Wal-Mart also said Walton pursued a variety of business interests throughout his life, including forming the holding company True North, which is composed of operations ranging from advanced composites to boat building to venture capital investments.

JCK