On March 29, 1969, First Lieutenant Hess and Captain William J. Popendorf were the crew in an F-4D on an herbicidal spray mission to defoliate a segment of Route 915 that lay near Ban Topen, 15 miles southwest of the Ban Karai Pass in the Ban Laboy area of Khammouane Province.
As the formation of 3 aircraft was on its second run at an altitude of 100-200 feet and at a possible air speed of 500 knots, they were hit by small arms fire causing an explosion in the left rear of the aircraft. Their aircraft went into a shallow climb and at 500-600 feet it began to roll to the left. The aircraft started rolling uncontrollably, and the crew ejected moments before the aircraft crashed into a hillside in the area of Route 915.
Captain Popendorf's parachute was not fully deployed when he landed, but had snagged in a tree. Popendorf radioed that he was alive on the ground with a broken arm and right leg. He was subsequently rescued.
Captain Popendorf reported that he heard Lieutenant Hess eject prior to his own ejection from the aircraft. Lieutenant Hess was declared missing in action.
Hess was promoted to the rank of Major during the period he was maintained missing. Hess was presumptively declared killed in action on May 22, 1979, based on no new information to prove he was alive. His body has not been recovered.
Hess was survived by a young wife and daughter, Bahar and Christine, and his parents, Lt Col & Mrs. Frederick W Hess.
Major Hess’s name in inscribed on The Vietnam Veterans Memorial, Panel 28W - Line 81, and at the Lt. Charles Garrison Veterans Memorial, Section B – Line 46.
