ACR MLG NON ADHERENCE TO ATC CLRNC DURING DESCENT AND APCH TO A NON TWR ARPT.

Narrative

WE WERE FLYING INTO IDAHO FALLS; TWR CLOSED; 1700 OVERCAST; 3 MI; SNOWCOVERED RWY; BRAKING RPTED FAIR; WIND 0405. WE CALLED AHEAD TO IDAHO FALLS RADIO; CTAF; AND GOT THE WX INCLUDING THAT RWY 02 WAS THE 'RWY OF PREFERENCE.' AS WE APCHED IDAHO FALLS SALT LAKE CENTER CLRD US FOR WHAT WE THOUGHT WAS THE APCH TO RWY 02. WE WERE HIGH AND FAST SO WE REQUESTED A 360 DEG TURN TO GET DOWN AND SLOW DOWN. WE THOUGHT SALT LAKE CENTER SAID; 'YOU'RE CLRD; CLRD APCH; GO TO ADVISORY.' WE WENT TO IDAHO FALLS RADIO; CTAF; TOLD HIM WE WERE DOING A 360 DEG TURN AND APCH TO 02. HE ACKNOWLEDGED. AS WE COMPLETED A TIGHT 360 DEG TURN; RADIO SAID; 'GO BACK TO CENTER.' WE DID AND HE INFORMED US WE WERE NOT CLRD FOR A 360 DEG TURN AND WERE NOT CLRD FOR THE APCH TO 02; BUT 20. WE TOLD CENTER WE COULDN'T ACCEPT A LNDG ON RWY 20 WITH BRAKING FAIR AND A TAILWIND. WE WERE RECLRED FOR RWY 02. AFTER LNDG WE DISCUSSED THE WHOLE SITUATION AT LENGTH WITH SALT LAKE CENTER AND FORTUNATELY THERE WERE NO TFC CONFLICT. WHAT WE LEARNED WAS THAT AT UNCONTROLLED ARPTS WHERE CENTER IS PROVIDING APCH CLRNC WE SHOULD HAVE REQUESTED THE APCH WE WANTED BASED ON THE CONDITIONS RATHER THAN ASSUMING THERE WAS COORD BTWN CTAF AND CENTER ABOUT THE 'RWY OF PREFERENCE.' THAT WOULD HAVE PREVENTED THE CONFUSION AND OUR HEARING 02; BECAUSE IT WAS THE LOGICAL RWY FOR US; WHEN IN FACT THE CTLR WAS SAYING 20. SUPPLEMENTAL INFORMATION FROM ACN 80178: AS AIR CARRIER PLTS WE'RE NOT ACCUSTOMED TO OPERATIONS AT UNCONTROLLED ARPTS. STRANGE ARPT TO BOTH PLTS; WITH POTENTIALLY HAZARDOUS RWY CONDITIONS AT A HIGH FIELD ELEVATION. WE ASSUMED THAT CENTER WOULD BE COORDINATING WITH THE IDA FSS.