THE FLC THOUGHT THEY WERE ON VECTORS TO THE ARPT. THE CTLR THOUGHT THE CREW WAS EXPECTING VECTORS BUT STILL ON THE ACTON ARR UNTIL ASSIGNED A VECTOR. CONSEQUENTLY; THE FLC DID NOT TURN AT THE APPOINTED POINT ON THE ARR AND SURPRISED THE CTLR.

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WHILE FLYING THE ACTON 4 ARR WE WERE ORIGINALLY TOLD TO EXPECT RWY 18R THEN WE WERE TOLD TO DSND TO 5000 FT MSL; SLOW TO A SPECIFIED AIRSPD AND EXPECT VECTORS TO RWY 13R. BOTH THE CAPT AND MYSELF WERE EXPECTING THE VECTOR AND SUBSEQUENTLY MISSED THE TURN TO THE 350 DEG HDG AT CREEK INTXN AT 32 DME. WE TALKED ABOUT HOW APCH CTL WAS BRINGING US IN VERY CLOSE TO RWY 13R FOR THE VECTOR TO DOWNWIND. AT 36 DME OFF ACTON VOR APCH GAVE US THE TURN AND A DSCNT. AFTER WE STARTED THE TURN AND DSCNT; THE CTLR QUESTIONED OUR LATE TURN AND HAD US MOMENTARILY STOP THE DSCNT (NOT GIVEN REASON WHY) THEN RESUME THE DSCNT AND SWITCHED TO THE NEXT CTLR. WE (THE CAPT AND MYSELF) ARE FLYING THE SAME SEQUENCE ALL MONTH. THE PREVIOUS TIME ON THIS ARR WE WERE GIVEN A HDG OUT OF HULEN INTXN AND WERE BROUGHT VERY CLOSE TO THE RWY PRIOR TO THE TURN TO DOWNWIND; VERY SIMILAR TO OUR POS DESCRIBED ABOVE. THE TEXT OF THE ARR CLRLY STATES A TURN AT CREEK AND NOTHING THE CTLR SAID CHANGED THAT; BUT WE BOTH (THE CAPT AND I) THOUGHT WE WERE OFF THE ARR WAITING FOR A VECTOR OFF OUR CURRENT HDG INSTEAD OF WAITING TO TURN AT CREEK INTXN ON THE VOR COURSE.