Narrative:

It was a beautiful clear day in san. It was my second approach into runway 27 at san within about the last 3 yrs. The day previous, ATC handled our flight completely differently. We were flying into san from the wnw. We were on about the 300 degree radial of mzb VOR cleared to mzb VOR direct san. We could see the airport from many mi out, but did not yet report it in sight. A few mi before mzb VOR, socal approach turned us 10 degrees left to an assigned heading of 110 degrees radar vectors to the visual approach to runway 27 san. In the vicinity of mzb VOR, ATC asked us if we had the airport in sight. We called the airport in sight. Socal approach cleared us for the visual approach to runway 27, and to cross the mzb 084 degree radial at 5000 ft MSL. (This I assumed was to keep us in the class B airspace.) at this point we were either descending to 5000 ft or level at 5000 ft MSL. We were crossing just north of the mzb VOR. My navigation instruments were set up for the localizer to runway 27 (because we were on a radar vector). I had the first officer set up the mzb 084 degree radial. Then, I assumed on our current track and heading we should cross the mzb VOR 084 degree radial close to the VOR, so, at about 6 mi east of mzb VOR, I started down from 5000 ft MSL (assuming I already passed the mzb 084 degree radial) and completed the right base visual to runway 27. From the moment we were cleared for the visual, the cockpit workload was very busy. Problem: I may have descended below 5000 ft MSL before crossing the mzb 084 degree radial. Contributing factors: 1) it was dawn and I was feeling fatigued (hitting a sinker). 2) I assumed my assigned heading would track across the mzb 084 degree radial. 3) the WX was so nice. It may have made me complacent. 4) ATC handled us differently the day before. 5) my flight instruments were set up for the runway, not the mzb VOR. How to avoid in the future: 1) when given a clearance to cross a certain radial/fix at a certain altitude, never assume it is complied with. Always set up the navigation radios to verify compliance. 2) in VFR WX on a visual approach, always set up someone's navigation radios to navigation in and through the class B airspace. 3) extend further downwind to allow more time for the approach.

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Original NASA ASRS Text

Title: A B727 CREW, ON APCH TO SAN, DEPARTED ASSIGNED ALT PREMATURELY, PRIOR TO XING ASSIGNED RADIAL.

Narrative: IT WAS A BEAUTIFUL CLR DAY IN SAN. IT WAS MY SECOND APCH INTO RWY 27 AT SAN WITHIN ABOUT THE LAST 3 YRS. THE DAY PREVIOUS, ATC HANDLED OUR FLT COMPLETELY DIFFERENTLY. WE WERE FLYING INTO SAN FROM THE WNW. WE WERE ON ABOUT THE 300 DEG RADIAL OF MZB VOR CLRED TO MZB VOR DIRECT SAN. WE COULD SEE THE ARPT FROM MANY MI OUT, BUT DID NOT YET RPT IT IN SIGHT. A FEW MI BEFORE MZB VOR, SOCAL APCH TURNED US 10 DEGS L TO AN ASSIGNED HDG OF 110 DEGS RADAR VECTORS TO THE VISUAL APCH TO RWY 27 SAN. IN THE VICINITY OF MZB VOR, ATC ASKED US IF WE HAD THE ARPT IN SIGHT. WE CALLED THE ARPT IN SIGHT. SOCAL APCH CLRED US FOR THE VISUAL APCH TO RWY 27, AND TO CROSS THE MZB 084 DEG RADIAL AT 5000 FT MSL. (THIS I ASSUMED WAS TO KEEP US IN THE CLASS B AIRSPACE.) AT THIS POINT WE WERE EITHER DSNDING TO 5000 FT OR LEVEL AT 5000 FT MSL. WE WERE XING JUST N OF THE MZB VOR. MY NAV INSTS WERE SET UP FOR THE LOC TO RWY 27 (BECAUSE WE WERE ON A RADAR VECTOR). I HAD THE FO SET UP THE MZB 084 DEG RADIAL. THEN, I ASSUMED ON OUR CURRENT TRACK AND HDG WE SHOULD CROSS THE MZB VOR 084 DEG RADIAL CLOSE TO THE VOR, SO, AT ABOUT 6 MI E OF MZB VOR, I STARTED DOWN FROM 5000 FT MSL (ASSUMING I ALREADY PASSED THE MZB 084 DEG RADIAL) AND COMPLETED THE R BASE VISUAL TO RWY 27. FROM THE MOMENT WE WERE CLRED FOR THE VISUAL, THE COCKPIT WORKLOAD WAS VERY BUSY. PROB: I MAY HAVE DSNDED BELOW 5000 FT MSL BEFORE XING THE MZB 084 DEG RADIAL. CONTRIBUTING FACTORS: 1) IT WAS DAWN AND I WAS FEELING FATIGUED (HITTING A SINKER). 2) I ASSUMED MY ASSIGNED HDG WOULD TRACK ACROSS THE MZB 084 DEG RADIAL. 3) THE WX WAS SO NICE. IT MAY HAVE MADE ME COMPLACENT. 4) ATC HANDLED US DIFFERENTLY THE DAY BEFORE. 5) MY FLT INSTS WERE SET UP FOR THE RWY, NOT THE MZB VOR. HOW TO AVOID IN THE FUTURE: 1) WHEN GIVEN A CLRNC TO CROSS A CERTAIN RADIAL/FIX AT A CERTAIN ALT, NEVER ASSUME IT IS COMPLIED WITH. ALWAYS SET UP THE NAV RADIOS TO VERIFY COMPLIANCE. 2) IN VFR WX ON A VISUAL APCH, ALWAYS SET UP SOMEONE'S NAV RADIOS TO NAV IN AND THROUGH THE CLASS B AIRSPACE. 3) EXTEND FURTHER DOWNWIND TO ALLOW MORE TIME FOR THE APCH.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.