MLG FLC TURNED DURING A VECTOR APCH TO THE WRONG HDG DUE TO MISINTERPING THE CLRNC TO MEAN HDG RATHER THAN AIRSPD.

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ACFT WAS AT 6000 FT DOWNWIND FOR RWY 22 ON A HDG OF 085 DEGS WAS TOLD TO TURN ANOTHER 10 DEGS R. WE TOLD CTLR WE HAD THE ARPT. HE SAID WE WILL GO OUT ANOTHER COUPLE OF MI. THE CTLR SAID TO DSND TO 2000 FT. HAD ACFT CONFIGURED TO 180 KIAS AND FLAPS 15 DEGS FOR A SHORT APCH. CTLR SAID 180 DEGS. I READ BACK 180 DEGS AND WE TURNED TO 180 DEGS. IN THE TURN WE SAW A B737 VISUALLY AND ON TCASII. WE FIGURED WE WOULD BE TURNED ON A VISUAL APCH BEHIND THE B737. LEAVING 3400 FT; THE CTLR ASKED US WHERE WE WERE GOING. WE TOLD HIM WE WERE ON 180 DEG HDG. HE TOLD US TO LEVEL AT 3000 FT AND THEN HE GAVE US A L 270 DEG TURN FOR FINAL; AND TOLD US TO CALL TWR UPON LNDG. I CALLED THE SUPVR AND HE JUST REVIEWED THE TAPES AND SAID THE 180 DEG READBACK DID NOT MENTION AIRSPD OR HDG. HE SAID THERE WAS NO TFC SEPARATION PROB; BUT NEXT TIME READ BACK 180 KTS OR HDG SO THE CTLR WOULD KNOW WHAT WAS HAPPENING. AT ALL TIMES WE HAD OTHER ACFT B737 IN SIGHT AND ASSUMED A TIGHT VISUAL APCH BEHIND HIM. APCH CTLR WAS BUSY WITH A LOT OF TFC.