THE AIRPLANE HAD JUST DEPARTED THE AIRPORT TOWING A GLIDER. AT ABOUT 300 FEET MSL THE TOW PLANE WENT INTO A NOSE LOW DIVE. THE GLIDER PILOT RELEASED THE TOW LINE AND LANDED SAFELY. THE TOW PLANE CRASHED IN A FIELD. ACCORDING TO THE PILOT'S MEDICAL HISTORY HE HAD A PRE-EXISTING HEART CONDITION. THE MEDICAL EXAMINER DETERMINED THE CAUSE OF DEATH AS: '...ACUTE CORONARY INSUFFICIENCY DUE TO SEVERE CORONARY ARTERIOSCLEROSIS.'