DURING THE EARLY MORNING HOURS, THE ACFT CRASHED AT THE EDGE OF A WHEAT FIELD ON RELATIVELY LEVEL TERRAIN. THE MAIN WRECKAGE THEN CROSSED A ROAD & CAME TO REST IN ANOTHER FIELD. THERE WERE NO KNOWN WITNESSES. A PASSING FARMER DISCOVERED THE WRECKAGE AT ABOUT 0830 CST. THE MEDICAL EXAMINER ESTIMATED THE OCCUPANTS WERE FATALLY INJURED AT APRX 0600. HOWEVER, THE TOWER HAD BEEN MANNED AT 0540 & NO RADIO CALLS WERE RECEIVED FROM THE ACFT AFTER THAT TIME. THUS, THE TIME OF THE ACCIDENT WAS PRESUMED TO BE AT ABOUT 0530. AT 0600, THE 1ST WX OBSERVATION AT ENID, OK WAS: 500 FT BROKEN,25,000 FT OVERCAST, VISIBILITY 4 MI WITH FOG. BY 0632, THE WX HAD DETERIORATED TO 100 FT OBSCURED WITH FOG. N EXAM OF THE WRECKAGE REVEALED THE ACFT HAD IMPACTED LEFT WING 1ST, WHILE IN NEAR WINGS LEVEL FLT. NO PREIMPACT. MECHANICAL PROBLEM WAS EVIDENT. BOTH OCCUPANTS HAD BEEN OBSERVED DRINKING UNTIL APRX 0130. A CHECK OF THE PLT'S BLOOD REVEALED AN ALCOHOL LEVEL OF 0.11%. THE ACFT CRASHED ABOUT 4 MI SE OF THE ARPT, HEADED NW.