A KING AIR TURBO DEVIATES FROM THE ILS COURSE AND GS ON AN APCH TO ORD RWY 27L TO AVOID WAKE TURB OF A B727 AHEAD. VECTORED OFF BY APCH FOR ANOTHER TRY.

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ATIS WAS CALLING THE WX ABOUT 2500 FT OVCST; 10 MI VISIBILITY; WINDS 320 DEGS GUSTING TO 13 KTS; SIMULTANEOUS APCHS RWY 27L&R. WE WERE TALKING WITH APCH AND TOLD TO EXPECT THE L SIDE. WE BRIEFED THE APCH. AFTER SEVERAL TURNS BECAUSE OF HVY TFC AND A DSCNT TO 5000 FT; WE WERE CLRED FOR THE ILS RWY 27L; 5000 FT UNTIL ESTABLISHED; 170 KTS TO WILLT; CALL THE TWR AT WILLT; 120.75; CAUTION; WAKE TURB; YOU'RE FOLLOWING A B727. AT THIS POINT; WE WERE JUST OUTSIDE WAVIE; AND DECIDED TO FLY A LITTLE HIGH ON THE GS AND 1/2 - 1 DOT UPWIND TO AVOID THE PRECEDING ACFT'S WAKE. TOPS WERE ABOUT 8000 FT VARIABLE; SO WE WERE IMC. WHILE DSNDING THROUGH ABOUT 4700 FT MSL; THE MONITOR CTLR SAID 'TURN L IMMEDIATELY; DO NOT DSND; CLB TO 5000 FT; MAINTAIN 5000 FT UNTIL ON THE LOC. YOU ARE CLOSE TO AN ACFT (OR WORDS TO THAT EFFECT) ON THE ILS RWY 27R.' WE COMPLIED IMMEDIATELY; REINTERCEPTED; AND CONTINUED THE APCH UNEVENTFULLY. HAVING FLOWN ALL AROUND THE UNITED STATES DURING THE PAST 20 YRS; I CONSIDER THE ORD CTLRS AMONG THE BEST. I HAVE ALSO FLOWN INTO AND OUT OF ORD HUNDREDS OF TIMES; USING THE SAME TECHNIQUE; BUT THIS WAS THE FIRST TIME I HAD RECEIVED AN ALERT FROM A MONITOR. ALTHOUGH STILL PUZZLED BY THE SEEMING CONTRADICTION BTWN WAKE AVOIDANCE AND PROTECTED AIRSPACE; OTHER PLTS I SPOKE WITH LATER SAID THEY WOULD HAVE STAYED ON THE LOC; BUT FLOWN HIGH ON THE GS. PERHAPS THIS CAN BENEFIT SOMEONE ELSE.