FLT CREW OF B757 FAIL TO MEET XING RESTR AT SWATT INTXN ON LOC RWY 27 APCH TO SAN. ERROR DUE TO IMPROPERLY OPERATED AUTOFLT SYS.

Narrative

THE FOLLOWING APCH WAS TO BE CONDUCTED USING THE FMS DATABASE; AND COUPLED WITH THE AUTOPLT WITH VNAV -- SPD INTERVENTION. THE APCH WAS TO SAN; LOC RWY 27. WE WERE CLRED DIRECT TO THE SWATT INTXN AND TOLD TO MAINTAIN 3800 FT MSL. APCH CTL FOLLOWED WITH APCH CLRNC FOR THE LOC RWY 27 APCH. THE FO TRIED UNSUCCESSFULLY TO EXECUTE A DIRECT INTERCEPT INTO SWATT (272 DEG MAGNETIC); AND AFTER SEVERAL ATTEMPTS DECIDED TO TURN HIS ATTN OUTSIDE THE COCKPIT TO LOOK FOR THE ARPT AND CONFIGURE THE AIRPLANE FOR LNDG. I SUBSEQUENTLY WENT INSIDE TO COMPLETE HIS REQUEST FOR THE DIRECT INTERCEPT. THE AUTOPLT CAPTURED THE MCP ALT OF 3800 FT; AND CAPTURED THE LOC FOR RWY 27. WE DIALED IN THE MCP ALT WINDOW 660 FT MINIMUMS FOR THE APCH; OPENED THE VNAV SPD INTERVENTION WINDOW AND SLOWED THE AIRPLANE TO 180 KTS. WHAT I FAILED TO NOTICE IS THE 'HARD' ALT OF 3600 FT AT SWATT WENT TO A 'SOFT' 2867 FT. WE PASSED SWATT AT 2800 FT; 200 FT BELOW THE CLASS B AIRSPACE AND 800 FT BELOW THE SEGMENT ALT OF 3600 FT. SUPPLEMENTAL INFO FROM ACN 622240: I CROSSED REEBO AT 2000 FT AND DISCONNECTED THE AUTOPLT AND FLEW THE ACFT USING PAPI AND THE PDI FOR VISUAL GS REF. AFTER PARKING ON THE GATE WE REVIEWED THE ERRORS MADE BY THE ALT XING ERROR AND THE CLASS B AIRSPACE VIOLATION. WE REVIEWED THE AFM TO DISCOVER THE ERROR WAS MADE BY PREMATURELY SELECTED AIRSPD INTERVENTION.