The Safety Board's full report on this investigation is provided as Aviation Accident Report number AAR-86/02. To obtain a copy of this report, or to view the executive summary online, please see the Web site at http://www.ntsb.gov/publictn/publictn.htm AT ABOUT 1903 EDT, WHILE ENROUTE AT FL 330, THE CABIN CREW DISCOVERED A FIRE IN THE AFT LAVATORY. AFTER CONTACTING ATC & DECLARING AN EMERGENCY, THE FLT CREW MADE AN EMERGENCY DESCENT & ATC VECTORED THE ACFT TO THE GREATER CINCINNATI INTL ARPT. AT 1920, THE ACFT WAS LANDED ON RWY 27L. AS THE AIRCREW STOPPED THE PLANE, FIRE DEPT PERSONNEL MOVED IN PLACE & BEGAN FIREFIGHTING OPERATIONS. ALSO, AS THE PLANE STOPPED, THE OCCUPANTS BEGAN EVACUATING THE ACFT. ABOUT 60 TO 90 SEC AFTER THE EXITS WERE OPENED, A FLASH FIRE ENVELOPED THE INTERIOR OF THE ACFT. 23 PASSENGERS WERE UNABLE TO EXIT THE ACFT & DIED IN THE FIRE. AN INVESTIGATION REVEALED THAT 3 FLUSH MOTOR CIRCUIT BREAKERS HAD POPPED ABOUT 11 MIN BEFORE SMOKE WAS DETECTED. THE CAPTAIN MISCONSTRUED REPORTS THAT THE FIRE WAS ABATING WHEN HE RECEIVED CONFLICTING FIRE PROGRESS REPORTS. SUBSEQUENTLY, HE LANDED AT THE CINCINNATI INTL ARPT RATHER THAN AT LOUISVILLE WHICH WOULD HAVE ALLOWED HIM TO LAND 3 TO 5 MIN SOONER. WET TOWELS & BREATHING THRU CLOTHING AIDED SURVIVAL. FIRE SOURCE UNK.