NTSB Probable Cause

THE PILOT INITIATING AN INSTRUMENT FLIGHT WITHOUT OPERATING AIR/GROUND COMMUNICATIONS EQUIPMENT, AND HIS FAILURE TO MAINTAIN ADEQUATE TERRAIN CLEARANCE AFTER APPARENTLY DECIDING TO RETURN TO THE AIRPORT. FACTORS CONTRIBUTING TO THE ACCIDENT WERE INOPERATIVE COMMUNICATIONS EQUIPMENT RESULTING IN THE PILOT'S INABILITY TO ESTABLISH COMMUNICATION WITH ATC, ADVERSE WEATHER CONDITIONS, AND THE DARK NIGHT.