Narrative:

Turning base to final on a vector thru the localizer; we encountered wake turbulence behind a heavy. ATC advised us to maintain 160 KIAS to bugse. 2 miles prior to bugse; we noticed on TCAS that we were within 5 miles separation from the heavy. We started to slow the aircraft to approach speed without notifying the controller. Crossing bugse; we contacted the tower; tower asked for our speed which we told them was 140 KTS slowing to target speed 138 KTS. We ran the final descent checklist to an uneventful landing. Looking back on this event; I should have advised the controllers that we were slowing down prior to bugse.

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Original NASA ASRS Text

Title: A B757 ENCOUNTERED WAKE TURBULENCE BEHIND A HEAVY ACFT ON APCH TO ORD RWY 10 AND SLOWED THE APCH SPD AFTER ATC GAVE AN ASSIGNED SPD.

Narrative: TURNING BASE TO FINAL ON A VECTOR THRU THE LOCALIZER; WE ENCOUNTERED WAKE TURB BEHIND A HEAVY. ATC ADVISED US TO MAINTAIN 160 KIAS TO BUGSE. 2 MILES PRIOR TO BUGSE; WE NOTICED ON TCAS THAT WE WERE WITHIN 5 MILES SEPARATION FROM THE HEAVY. WE STARTED TO SLOW THE ACFT TO APCH SPEED WITHOUT NOTIFYING THE CTLR. CROSSING BUGSE; WE CONTACTED THE TOWER; TOWER ASKED FOR OUR SPEED WHICH WE TOLD THEM WAS 140 KTS SLOWING TO TARGET SPEED 138 KTS. WE RAN THE FINAL DSCNT CHECKLIST TO AN UNEVENTFUL LNDG. LOOKING BACK ON THIS EVENT; I SHOULD HAVE ADVISED THE CTLRS THAT WE WERE SLOWING DOWN PRIOR TO BUGSE.

Data retrieved from NASA's ASRS site as of May 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.