POTENTIAL CONFLICT DURING ALT EXCURSION BY THE FLT CREW OF AN A319 WHEN TFC WAS POINTED OUT ABOVE AND BELOW WITH FLT 20 NM W OF TOMSN INTXN; CO.

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ENRTE FROM SACRAMENTO TO DENVER PAST OUR ANTICIPATED DSCNT POINT; ZDV ADVISED US TO EXPECT DSCNT IN 4 MINS AND TO ACCELERATE TO BEST FORWARD SPD. I ADVISED ZDV THAT WE WOULD HAVE DIFFICULTY MAKING THE SPD AND ALT RESTR OVER TOMSN INTXN AND WOULD NEED RELIEF. ZDV THEN GAVE US A TA ABOVE AND BELOW OUR ALT. THE FO; PF; WAS IN THE PROCESS OF CLRING A RTE DISCREPANCY IN THE FMCG. I THEN LOOKED UP AND NOTICED WE WERE DSNDING TO FL350. MEANWHILE A TA ALERT WARNED US OF TFC; UNSURE FOR A MOMENT WHICH TFC (ABOVE OR BELOW) WAS A POTENTIAL CONFLICT I COULD NOT ISOLATE THE PROB. ALMOST SIMULTANEOUSLY ATC QUESTIONED OUR ALT. I WAS UNSURE AS TO HOW THE FCU ALT GOT RESET. I PRESUMED I MISSED A CALL AND CLBED BACK TO FL340. I CAN SURMISE THAT WHEN THE ACFT WAS COMMANDED TO DSND BY THE FO THAT IT PUSHED OVER TO CAPTURE THE DSCNT PATH AND CORRECT THE HIGH PROFILE. THIS RESULTED IN A HIGH RATE OF DSCNT THEREBY REDUCING REACTION TIME TO RESOLVE THE ALT SET IN THE FCU. I NEVER ACKNOWLEDGED FL350 AS AN ALT ASSIGNMENT YET THE FO INITIATED THE DSCNT BELOW FL370. THE FO DID NOT ANNOUNCE THE FCU CHANGE. THE DISTANCE OR TIME REMAINING TO THE ANTICIPATED RESTR CREATED A HIGH WORKLOAD ENVIRONMENT IN WHICH TO ACCOMPLISH ALL REQUIRED TASKS IN THE DSCNT. IN ADDITION; RADIO CONGESTION DID NOT ALLOW AN OPPORTUNITY TO QUESTION THE DISCREPANCY QUICKLY. SUPPLEMENTAL INFO FROM ACN 587820: ATC MUST HAVE GIVEN US A TA AT FL350 AND WE HEARD DSND FL350 AND STARTED DSCNT AND REPLIED DSND FL350. THIS WAS A MISUNDERSTANDING OF ATC INSTRUCTIONS OR ATC FORGOT HE TOLD US TO DSND. MISCOM IS THE MOST DANGEROUS PART OF OUR JOB.