ACR X NON ADHERENCE TO ATC INSTRUCTIONS.

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ACR X FLYING THE BIG SUR 1 ARR INTO SFO; WE WERE GIVEN A DSCNT TO 6000 FT AFTER PASSING BOULDER. (OAK 151 DEGS RADIAL AT 34 NM). I KNEW THAT 2 HVY ACFT WERE IN THE VICINITY BUT DID NOT SEE EITHER ONE. AFTER WE RPTED THE FIELD IN SIGHT; WE WERE CLRED FOR THE TIPTOE VISUAL TO RWY 28L. I THEN HEARD APCH TELL ACR Y; A 747; TO 'EXPECT BASE TURN IN 10 MI FOR THE VISUAL TO RWY 28R.' I TOLD THE FO THAT I SAW A POTENTIAL JOIN-UP DEVELOPING. APCH THEN SLOWED US TO 180 KTS. I SPOTTED THE B747 ON A HIGH DOWNWIND FOR RWY 28R. THE B747 RPTED THE FIELD AND US IN SIGHT (AFTER HE WAS GIVEN A HDG OF 230 DEGS) AND WAS CLRED FOR THE VISUAL TO RWY 28R. BECAUSE THE 747 WAS HEADING DIRECTLY AT US AND ABOVE US; I ASKED APCH (IN RESPONSE TO THEIR QUERY IF I HAD THE 747 IN SIGHT); 'WHAT ARE HIS INTENTIONS?' APCH SAID 'HE'S A VISUAL FOR THE R AND YOU'RE FOR THE L.' SINCE THIS WAS OBVIOUSLY AN INTENTIONAL JOIN-UP WITH WINGTIP-TO-WINGTIP FLYING; I SAID; 'I WANT TO BE IN FRONT OF THE 747.' APCH SAID; 'YOU WILL BE. HE WILL MAINTAIN VISUAL ON YOU.' IT WAS OBVIOUS TO ME THAT 180 KTS WOULD NOT KEEP ME IN FRONT; SO I INCREASED TO 200 KTS TO GET SOME SEPARATION; AND THEN COMMENCED SLOWING TO STAY BEHIND ANOTHER 747 ON SHORT FINAL FOR THE R 4 MI AHEAD. I TOLD THE FO THAT I WOULD STAY 2 DOTS HIGH WITH A LITTLE EXTRA SPD (WIND WAS 310 DEGS AT 19 KTS AND LOW LEVEL WINDSHEAR ADVISORIES WERE IN EFFECT). I ALSO TOLD THE COPLT TO TELL ME IF THE Y 747 WAS ABOUT TO PASS US; BECAUSE I WOULD BE GOING AROUND. I MADE A HIGH APCH AND LONG LNDG AND STILL FELT THE 747'S VORTICES. CHARTED VISUALS ARE UNSAFE. HAD THE Y 747 AND US FOLLOWED THE CTLR'S INSTRUCTIONS; A VERY HAZARDOUS SIT; (OVERSHOOT; MID-AIR COLLISION; WAKE VORTEX UPSET) MAY HAVE OCCURRED.