A B757-200 TAXIING TO THE GATE AT SFO HAD TO STOP ABRUPTLY TO AVOID A COLLISION WITH A B747 TAXIING UNDER AIRLINE RAMP CTL.

Narrative

WE HAD TO STOP THE ACFT TO AVOID A GND COLLISION WITH A B747. WE WERE ON TXWY B; TAXIING TO GATE X; WHILE THE B747 WAS PUSHED BACK ONTO THE S LINE; HOLDING ABEAM GATE Y. WE CALLED RAMP CTL AT THE TOP OF THE ALLEY AND THEY CLRED US INTO THE ALLEY VIA THE N LINE TO GATE X. AS WE STARTED OUR TURN; WE NOTICED THAT THE B747 HAD STARTED TAXIING AND WAS TURNING ONTO TXWY A. WE STOPPED ON B4 WITH BARELY ENOUGH ROOM FOR THE B747 TO GO BY. SINCE WE HAD NOT HEARD THE B747'S TAXI CLRNC; WE ASKED SFO GND IF THE B747 WAS SUPPOSED TO WAIT FOR US. THEIR RESPONSE WAS THAT IT WAS A RAMP CTL ISSUE. ACR RAMP; WHEN ASKED THAT SAME QUESTION; SAID THAT THE B747 WAS UNDER GND CTL AT THAT POINT. THIS HIGHLIGHTS A POTENTIAL PROB --BOTH ACFT WERE ON THEIR PROPER (THOUGH DIFFERENT) RADIO FREQS; TRYING TO TAXI IN THE SAME AREA; YET THE 2 CTLRS WEREN'T/AREN'T COORDINATING WITH EACH OTHER. ONE ACFT TAXIING FROM THE S LINE TO TXWY A; UNDER SFO GND CTL. ANOTHER ACFT TURNING FROM TXWY B TO THE N LINE; UNDER ACR RAMP CTL -- THIS SETUP WILL CAUSE A GND COLLISION SOME DAY.