POTENTIAL CONFLICT BTWN A G4 AND A B747 DURING A SPLIT FREQ OP THAT FAILED TO PROVIDE PROPER TFC SEPARATION NEAR BGSF; FO.

Narrative

ON A FLT IN A GULFSTREAM 4 TO IQUALUIT; NEWFOUNDLAND (CYFB); THE WX WENT BELOW LNDG MINIMA. WE TOLD EITHER WINNIPEG OR MONTREAL CTR THAT WE WANTED TO LAND AT OUR ALTERNATE (SONDE STROMM; GREENLAND). WE WERE APPROX 150 MI E OF IQUALUIT WHEN WE WERE CLRED BY ATC TO SONDE STROMM (BGSF) VIA DIRECT FRO BAY; DIRECT SONDE STROMM. WE FLEW THE NEW COURSE TO OUR ALTERNATE SONDE STROMM. ABOUT 1 HR PRIOR TO LNDG AT SONDE STROMM; WE WERE CALLED BY ICELAND RADIO. ICELAND ASKED US IF WE WERE READY TO COPY CLRNC TO LONDON LUTON (EGGW). WE COPIED THE CLRNC TO EGGW THINKING THAT IT HAD TO BE THE CLRNC FOR THE NEXT LEG TO LUTON SINCE CANADIAN ATC HAD ALREADY CLRED US TO OUR ALTERNATE (SONDE STROMM). IT NEVER CROSSED OUR MINDS THAT THE CLRNC TO LONDON WAS FOR THE PRESENT LEG (ISSUED IN ERROR). SOMEWHERE IN THE ATC HDOF BTWN CANADA AND ICELAND; ICELAND WAS NOT INFORMED THAT WE WERE LNDG AT SONDE STROMM; GREENLAND. WHEN WE REACHED ABOUT 180 MI FROM SONDE STROMM; WE ASKED ICELAND FOR DSCNT INTO SONDE STROMM. ICELAND TOLD US TO STAND BY AND AFTER SEVERAL ATTEMPTS MADE BY US TO OBTAIN DSCNT CLRNC; IT BECAME OBVIOUS THAT ICELAND DID NOT KNOW THAT WE WERE LNDG AT SONDE STROMM. AFTER SEVERAL MINS OF CONFUSION AND DISBELIEF ON THE PART OF ATC AND OURSELVES (THE CREW); I FINALLY WAS ABLE TO CONTACT SONDE STROMM TWR AND THEY WERE ABLE TO GIVE US RADAR VECTORS FROM OUR THEN ALT OF FL380 TO THE LOC APCH AND NORMAL LNDG AT SONDE STROMM. OVER SONDE STROMM THERE WAS A B747 AIRLINER CRUISING AT FL370. WE WERE AT FL380 PRIOR TO OUR DSCNT AND RECEIVED A TA ON OUR TCASII. PLEASE NOTE THAT THERE WAS 1000 FT VERT SEPARATION FROM THE B747 AND ABOUT 1/2 MI LATERAL SEPARATION. DURING THE RADAR VECTORING FROM SONDE STROMM TWR; WE GAINED ADEQUATE SEPARATION FROM THE B747 AND WERE ABLE TO DSND FOR LNDG. I BELIEVE THAT THE MISCOM DURING THE ATC HDOF FROM CANADA TO ICELAND CAUSED THE PROB. ICELAND HAD NO IDEA THAT WE WERE CLRED TO AND WANTED TO LAND AT SONDE STROMM UNTIL WE ASKED FOR DSCNT CLRNC. ALSO DURING THE ISSUANCE OF THE CLRNC TO LONDON; LUTON; ICELAND DID NOT USE KEY PHRASES SUCH AS: 'OCEANIC RERTE' OR 'PLEASE SAY ESTIMATE FOR' (THE FIRST FIX) ON THE NEW CLRNC. CUES SUCH AS THESE WOULD HAVE ALERTED US THAT THIS WAS A CLRNC FOR THE PRESENT FLT; NOT A CLRNC FOR THE NEXT FLT FROM SONDE STROMM TO LONDON; LUTON WHICH IS WHAT WE THOUGHT THE NEW CLRNC WAS FOR. AS A CREW; WE COULD HAVE ASKED ICELAND WHY THEY ISSUED THE CLRNC BUT IT NEVER CROSSED OUR MINDS SINCE WE WERE PREVIOUSLY CLRED TO OUR ALTERNATE (SONDE STROMM) WHICH IS WHERE WE WANTED TO LAND. OTHER FACTORS INCLUDE: OUR FLT WEST COAST OF UNITED STATES DEPARTING AT XA30 AT OUR DOMICILE ARPT AND THEN FLYING FOR 6 HRS WHICH PUT US PAST OUR NORMAL BED TIME.