AT 1146 GMT, N4906K DEPTD ON A 5 HR FLT TO NARSSARSSUAQ, GREENLAND WITH AN ESTD 7 HRS OF FUEL. WHEN THE PLT RPRTD 60 MI SW OF GREENLAND, THE DESTN VIS WAS BELOW IFR MIN & THE CEILING AT THE ALTN ARPT WAS BELOW THE MDA. THE PLT ELECTED TO CONT TO REYKJAVIK, ICELAND. LATER, AFTER HE EXTENDED HIS ETA TO REYKJAVIK BY MORE THAN 1 HR & INDICATED LOW FUEL, ICE- LAND OFFICIALS BGN SEARCH/RESCUE PROCEDURES. USAF & ICELAND ACFT & SHIPS WERE DISPATCHED BFR THE ACFT RAN OUT OF FUEL. AT 1811, FUEL EXHAUSTION OCCURRED AS THE PLT WAS DSCNDG FM 15,000'. A USAF C-130 CREW RENDEZVOUSED WITH N4906K, LIGHTED THE OCEAN WITH FLARES & GAVE DITCHING ADVISE. THE PLT DITCHED IN HI SEAS APRX 36 MI WEST OF KEFLAVIK, ICELAND IN WINDS GUSTING TO 35 KTS. A USAF HELICOPTER ARRIVED 3 MIN LATER, BUT THE OCCUPANTS WERE NEVER OBSVD TO EMERGE FM THE DOWNED ACFT. RESCUE PSNL LOST SIGHT OF THE ACFT AT 1834. AT THAT TIME, THE SUN WAS 6 DEG BLO THE HORIZON. THE ELT SIGNAL CEASEDSHORTLY THEREAFTER. THE OCCUPANTS WERE PRESUMED TO HAVE BEEN FATALLY INJURED WHEN THE ACFT DITCHED/SANK IN THE OCEAN.