Narrative:

During a complicated arrival to sna, we were given several clrncs and crossing restr as well as speed changes. I believe we misunderstood the last clearance and crossing restr due to the high workload that was developing in the cockpit. The last clearance included a heading vector followed by direct to a fix and crossing altitude, followed by [instruction to] continue to 7000 ft, join the arrival and a speed restr. The controller was cutting the corner on the arrival to save time or distance for us. Unfortunately, this took us off of the STAR and back on with a frequency change and canceled our current VNAV profile to add a new one. We had too many clrncs in too short a period of time with nonstandard phraseology causing us to us to misinterp a restr. We were not informed of any conflict, nor did we receive any TA/RA alerts from TCASII. Supplemental information from acn 493040: we misunderstood the crossing restr and apparently deviated from what the controller believed was the assigned altitude. No conflicts were reported. The ATC system needs to avoid long, complicated or multiple clrncs. When a STAR is published, stick to it so you don't have to decipher clrncs after you're already in a busy approach environment.

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Original NASA ASRS Text

Title: FLC OF A WESTWIND IA1124 MISTAKENLY DID NOT MAKE XING RESTR ALT DURING VECTORS OFF AND BACK ON A STAR ARR.

Narrative: DURING A COMPLICATED ARR TO SNA, WE WERE GIVEN SEVERAL CLRNCS AND XING RESTR AS WELL AS SPD CHANGES. I BELIEVE WE MISUNDERSTOOD THE LAST CLRNC AND XING RESTR DUE TO THE HIGH WORKLOAD THAT WAS DEVELOPING IN THE COCKPIT. THE LAST CLRNC INCLUDED A HDG VECTOR FOLLOWED BY DIRECT TO A FIX AND XING ALT, FOLLOWED BY [INSTRUCTION TO] CONTINUE TO 7000 FT, JOIN THE ARR AND A SPD RESTR. THE CTLR WAS CUTTING THE CORNER ON THE ARR TO SAVE TIME OR DISTANCE FOR US. UNFORTUNATELY, THIS TOOK US OFF OF THE STAR AND BACK ON WITH A FREQ CHANGE AND CANCELED OUR CURRENT VNAV PROFILE TO ADD A NEW ONE. WE HAD TOO MANY CLRNCS IN TOO SHORT A PERIOD OF TIME WITH NONSTANDARD PHRASEOLOGY CAUSING US TO US TO MISINTERP A RESTR. WE WERE NOT INFORMED OF ANY CONFLICT, NOR DID WE RECEIVE ANY TA/RA ALERTS FROM TCASII. SUPPLEMENTAL INFO FROM ACN 493040: WE MISUNDERSTOOD THE XING RESTR AND APPARENTLY DEVIATED FROM WHAT THE CTLR BELIEVED WAS THE ASSIGNED ALT. NO CONFLICTS WERE RPTED. THE ATC SYS NEEDS TO AVOID LONG, COMPLICATED OR MULTIPLE CLRNCS. WHEN A STAR IS PUBLISHED, STICK TO IT SO YOU DON'T HAVE TO DECIPHER CLRNCS AFTER YOU'RE ALREADY IN A BUSY APCH ENVIRONMENT.

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.