One of the bestg known examples, taken from Wikipedia:
https://en.wikipedia.org/wiki/Dick_J...r_pilot)#Death

"Dick Johnson died July 23, 2008, at age 85. He was flying a Ventus A glider from a Midlothian, Texas airport[4] when it crashed about 2.25 miles (3.5 km) from the airport after flying for some time. The Medical Examiner of Dallas County determined that Johnson died from the injuries he received in the crash. The National Transportation Safety Board determined the probable accident cause to be an incapacitating cardiac event, as Johnson had severe coronary artery disease with symptoms and had been prescribed medication for it."