Dale Sr seatbelt broke when his car hit the wall. The belt did not break before. The reason it failed was Dale alterations to the safety harness ordered by Earnhardt, not because of a design flaw or failure of the mechanism and the way which Earnhardt had the belt installed likely caused its failure.

None the less even if he had the HANS device on he still would have slammed into the steering wheel. No helmet or hans device would have saved him. Maybe the safer barrer but still Dale was Dale and he was the best and no other driver even today is better.