SNA APCH CTLR UNAUTHORIZED DSCNT TO OCCUPIED ALT WITH ACR X. OPDEV.

Narrative

ACR X WAS BEING VECTORED FROM THE W TO A 25L APCH AT LAX. COAST APCH CTL ASSIGNED AN ALT CLRNC OF 'DSND TO AND MAINTAIN 6000 FT.' ALT CLRNC OF 6000 WAS READ BACK TO APCH CTL AND 6000 WAS SET IN ALT SELECT WINDOW. SHORTLY AFTER 6000 FT CLRNC WAS RECEIVED AND ACKNOWLEDGED COAST APCH DIRECTED US TO CONTACT LOS ANGELES APCH. FO CHKED IN WITH LOS ANGELES APCH AS ACFT WAS PASSING THROUGH 6500 FT AND REPEATED ALT ASSIGNMENT OF 6000 FT. AT THAT TIME LOS ANGELES APCH REPLIED 'WE NEED YOU AT 7000 FT; CLB AT THIS TIME TO 7000.' A CLB TO 7000 WAS IMMEDIATELY INITIATED AND LEVEL OFF AT 7000 FT OCCURRED APPROX 15 SECONDS LATER. NO KNOWN TFC CONFLICTS. SUPPLEMENTAL INFO FROM ACN 195598: ACR X CLRNC TO DSND TO 6000 FT MSL UNDERSTOOD AND READ BACK TO COAST APCH CTL. CHANGED FREQ TO LAX APCH CTL; ON INITIAL CONTACT FO RPTED OUT OF 7000 FOR 6000 FT WITH NO REMARK FROM APCH CTL THAN 'ROGER; DEPART SLI 330 DEG VECTORS FOR RWY 25L VISUAL APCH.' APCH CTL CALLED AND SAID 'YOUR ALT SHOULD BE 7000 FT; CLB TO 7000 NOW FOR TFC.' WE COMPLIED BUT STILL BELIEVE WE WERE INITIALLY CLRED TO 6000 FT. OUR DSCNT FROM 12000 FT (INITIAL XING RESTRICTION) WAS INTERRUPTED AT 8000 FOR TFC. WE WERE GIVEN NUMEROUS ACFT TO VISUALLY ACQUIRE; WHICH WITH HELP OF TCASII; WE ACCOMPLISHED.