NEW YORK, June 28: Billionaire John Walton, the second son of Wal-Mart Stores founder Sam Walton and a Wal-Mart board member, died on Monday when a small plane he was piloting crashed shortly after takeoff near his Wyoming home.

Mr Walton, an experienced pilot who was a resident of Jackson Hole, was flying a 400- to 500-pound home-made aircraft, with an aluminium body, cloth-covered wings and a small engine, Grand Teton National Park spokeswoman Joan Anzelmo said.

Park rangers were investigating the incident, she said, adding that the Federal Aviation Administration had declined to do so as it involved an unregistered aircraft.

The cause of the crash has not yet been determined, Wal-Mart said in a statement.

Mr Walton, 58, is ranked 11th on Forbes magazine’s most recent list of the world’s richest people, with a net worth estimated at $18.2 billion.

Mr Walton served in the US Army Green Berets as a medic during the Vietnam war. He was awarded a Silver Star for helping save the lives of several members of his unit while under intense enemy fire, according to Wal-Mart.

Throughout his life, Mr Walton pursued a variety of business interests, including crop dusting in the 1970s and boat building in the 1980s and 1990s. He is also a keen philanthropist.

Mr Walton is survived by his wife and their son, his mother, two brothers, a sister and their families. His brother S. Robson Walton is chairman of Wal-Mart’s board.

“This is a horrible tragedy. what is so unusual about this is it is the founder’s son,” Bill Dreher, a Wal-Mart analyst at Deutsche Bank, said. —Reuters