ALTDEV. COMPLICATED STAR; INEXPERIENCED FO.

Narrative

WE HAD BEEN CLRED TO DSND VIA THE JAMMN 1 ARR AND TO COMPLY WITH RESTRS. THE FO WAS FLYING AND I WORKED THE RADIOS. AFTER XING JAMMN INTXN AT 17000 FT WE DSNDED TO CROSS GRONK AT 13000 FT. WITH THE AUTOPLT ENGAGED WE LEVELED AT 13000 FT PRIOR TO GRONK. AFTER THE AUTOPLT CAPTURED THE ALT AT 13000 FT; I SET THE NEXT STEP DOWN OF 12000 FT FOR THE CHHIP INTXN. I NOTIFIED THE FO OF THE NEXT ALT; BUT DO NOT BELIEVE I SPECIFIED THE CHHIP INTXN. THEN I WENT TO OUR COMPANY FREQ TO CHK IN BEFORE DSNDING THROUGH 10000 FT. WHILE I WAS OFF THE ATC FREQ; THE FO INDICATED FOR ME TO RETURN AND INFORMED ME THAT ATC HAD INFORMED HER THAT WE WERE BELOW THE REQUIRED ALT. AT THIS TIME OUR ALT INDICATED 12400 FT AND WE HAD ALREADY CROSSED SPIEK INTXN. ATC REQUESTED WE CALL AND LATER INFORMED ME OF A POSSIBLE ALT VIOLATION. IT IS POSSIBLE THAT WE MAY HAVE DSNDED BELOW 13000 FT WHILE ON THE 7 MI LONG SEGMENT BTWN GRONK AND SPIEK INTXN BUT I CANNOT VERIFY THAT. I SEE 3 PROB AREAS AND POSSIBLE CAUSES FOR THIS ERROR. I SHOULD NOT HAVE SET 12000 FT INTO THE ALT CTL UNTIL ACTUALLY PASSING SPIEK INTXN. ALTHOUGH WE WERE ABOVE 10000 FT IT WAS NOT A GOOD TIME TO LEAVE THE ATC FREQ; AND CONSEQUENTLY THE COCKPIT LOOP. COMPANY COMS COULD HAVE BEEN DONE EARLIER OR NOT AT ALL. THE JAMMN 1 ARR IS COMPLICATED DUE TO NUMEROUS STEP DOWNS AND BY SERVING BOTH 'N' AND 'S' ARRS. WHILE THIS PROC GREATLY REDUCES CTLR WORKLOAD IT INCREASES PLT WORKLOAD GREATLY AND REQUIRES WAY TOO MUCH ATTN TO THE CHART. THIS SHOULD BE SIMPLIFIED AND DIVIDED INTO 2 SEPARATE CHARTS OR PROCS; ONE FOR 'N' AND ONE FOR 'S.' ALSO CONTRIBUTING: I MAY HAVE TOLD THE FO THAT WE HAD TO MAINTAIN 13000 FT UNTIL AFTER XING GRONK INSTEAD OF SPIEK; HOWEVER I AM NOT SURE OF IT. AT ANY RATE BETTER ATTN TO COCKPIT COM IS NEVER A MISTAKE. SUPPLEMENTAL INFO FROM ACN 324758: WE PASSED GRONK AND THE CAPT PUT 12000 FT INTO THE ALT ALERTER FOR THE NEXT ALT STEP DOWN. I ACKNOWLEDGED THE ALT AND THEN HE LEFT THE FREQ TO CALL COMPANY. THERE IS SOME CONFUSION AS TO WHAT POINT I STARTED MY DSCNT AS THE ARR REQUIRES 13000 FT AT SPIEK AND WE HAD ALREADY CROSSED GRONK INTXN. ALSO THE ALT ALERTER WAS SET FOR CHHIP INTXN NOT SPIEK INTXN. I STARTED MY DSCNT AND AT 12400 FT ATC ADVISED ME OF A TERRAIN PROX AND TO COMMENCE A CLB. WE DID NOT GET ANY TYPE OF GPWS WARNING. THEY INDICATED MY ALT WAS 12200 FT; HOWEVER MY ALTIMETER READ 12400 FT. THEY REQUESTED THAT WE GIVE THEM A CALL BECAUSE THEY HAVE HAD NUMEROUS OCCURRENCES OF THIS IN THAT AREA. AT THAT POINT I ASKED THE CAPT TO COME BACK TO FREQ AND I INFORMED HIM THAT ATC HAD INDICATED THAT WE WERE BELOW THE REQUIRED ALT. I LEVELED OFF AT 13000 FT AND RETRIMMED THE ACFT AND RE-ENGAGED THE AUTOPLT. I RECHKED MY CHART TO SEE IF I COULD DISCOVER WHERE THERE WAS A PROB WITH THE ALT. AT THE POINT WHEN THE CAPT HAD RETURNED TO FREQ WE HAD ALREADY PASSED SPIEK INTXN. THE CAPT QUERIED ATC TO DETERMINE WHERE THE ALT EXCURSION HAD OCCURRED. THE CTLR SAID HE WASN'T SURE BECAUSE HE DOESN'T HAVE THE CHART IN FRONT OF HIM; BUT THAT HE HAS HAD NUMEROUS PROBS WITH ALT ALERTS IN THAT AREA. HE THEN CLRED US TO DSND TO 9000 FT. AGAIN HE REQUESTED US TO PLEASE GIVE HIM A CALL BECAUSE THEY WANTED TO TALK TO US SO THAT THEY COULD BETTER DETERMINE WHERE THE PROB LAY ON THIS ARR. WHEN THE CAPT CALLED ATC THEY INFORMED HIM THEY WOULD BE PULLING THE TAPE FOR REVIEW AND IF THERE WAS AN ALT EXCURSION THAT THEY WOULD BE TURNING THE INFO INTO THE FLT STANDARDS DEPT. IT IS POSSIBLE THAT I MAY HAVE COMMENCED AN EARLY DSCNT BTWN THE 7 MI LONG SEGMENT BTWN GRONK AND SPIEK INTXN. HOWEVER I AM NOT SURE OF THE DME THAT I COMMENCED THE DSCNT TO CROSS CHHIP INTXN AT 12000 FT. I SEE SEVERAL PROB AREAS THAT COULD HAVE CAUSED THIS INADVERTENT ERROR. FIRST; WE SHOULD NOT HAVE SET 12000 FT INTO THE ALT ALERTER UNTIL XING SPIEK INTXN. SECOND AND FOREMOST THE JAMMN 1 ARR IS VERY COMPLICATED DUE TO NUMEROUS STEP DOWNS AND BY SERVING BOTH 'N' AND 'S' ARRS. WHILE THIS PROC REDUCES CTLR WORKLOAD IT GREATLY INCREASES PLT WORKLOAD DURING A CRITICAL PHASE OF FLT. IT REQUIRES WAY TOO MUCH ATTN TO THE CHART. I BELIEVE IT COULD BE SIMPLIFIED AND DIVIDED INTO 2 SEPARATE CHARTS; 1) N AND 2) S.