B737-300 FLC WERE ISSUED LOW ALT ALERT BY APCH CTLR WHEREIN THE FLC WERE AMAZED SINCE THEIR ALTIMETERS CONFIRMED THAT THEY WERE MAINTAINING THE PUBLISHED ALT.

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WE EXPERIENCED A NORMAL DSCNT AND WERE 'CLRED FOR THE LOC RWY 27 APCH; SAN DIEGO; 4000 FT UNTIL ESTABLISHED; 'AND ONCE INTERCEPTING THE LOC COURSE; DSND TO THE PUBLISHED ALT OF 3600 FT.' JUST PRIOR TO REACHING SWATT INTXN; SOCAL APCH CAME ON FREQ ASKING US TO 'STOP OUR DSCNT' AS THEY WERE RECEIVING A 300 FT LOW ALT (GPWS) WARNING ALERT ON OUR ACFT. WE REPLIED THAT WE WERE SORRY; BUT THAT WE WERE SHOWING 3600 FT AND HAD NOT YET BEGUN DSNDING TO OUR NEXT STEP-DOWN ALT. WE HELD THIS ALT UNTIL WELL PAST SWATT TO ENSURE NO CONFLICT; AND APPROX 1/2 MI AFTER SWATT; BEGAN OUR DSCNT TO THE NEXT ALT BEFORE OUR FAF; 2000 FT. MY FO AND I WERE BOTH VERY SURPRISED BY THIS SERIES OF CONFUSING PERCEPTIONS ON THE PART OF ATC. WE WERE NOT IN ANY CONFLICT WITH TERRAIN (THIS PORTION OF OUR APCH WAS TOTALLY VISUAL -- ONLY LATER DID WE ENCOUNTER A MARINE LAYER OF CLOUDS ON THE APCH TO SAN) OR OTHER ACFT. WE FELT THIS CTLR'S CONTINUED VERBAL CHALLENGES ABOUT OUR ALT CONSTITUTED A DISTR DURING A BUSY PORTION OF OUR LOC APCH. I DON'T KNOW IF THIS CTLR WAS RECEIVING A FAULTY MODE C XPONDER RETURN FROM US; OR IF IT WAS HIS GND RADAR PAINTING US 'LOW;' BUT IT SURE GRABBED OUR ATTN. ONE WOULD THINK THAT IF WE WERE TRULY '300 FT LOW' FROM OUR ASSIGNED/PUBLISHED LEGAL ALT; HE MIGHT HAVE ISSUED IMMEDIATE INSTRUCTIONS FOR A CLBING VECTOR AWAY FROM TERRAIN. IN ANY CASE; WE WERE GLAD TO AVOID ANY CONFLICT WITH TERRAIN; AND THE REMAINDER OF OUR LOC APCH AND LNDG AT SAN DIEGO WAS UNEVENTFUL. THIS CTLR SEEMED 'EDGY' AND TENSE WITH SEVERAL ACFT. IT APPEARED TO US ALMOST AS THOUGH HE WAS 'PUNISHING' US FOR PERSISTENTLY REQUESTING LOWER DURING OUR EARLIER PHASES OF THE DSCNT. THIS IS PROBABLY NOT THE CASE; BUT THE CTLR DID SEEM QUITE PRESSURED BY THE NUMEROUS GA ACFT HE WAS HANDLING; ALL OF WHICH WERE ENCOUNTERING LOW IFR MINIMUMS AT THEIR INTENDED ARPTS AND MANY OF WHOM SPOKE VERY BROKEN ENGLISH.