Narrative:

Approach to ord runway 9L following B777 5 mi in trail. WX 700 ft broken, 3 mi visibility or greater. Flew approach slightly high to avoid wake turbulence. No problems until in close. Settled to the GS at about 500 ft AGL. B777 delayed turning off the runway. At 250 ft AGL with B777 just turning off, our aircraft on speed and on GS with flaps 42 degrees we had a sudden left wing drop of 20-25 degrees and a 20 KT loss of airspeed with some left yaw go around initiated and recovery was uneventful. Normal landing on runway 4 followed. We were very comfortable on the approach and spacing did not seem to be a problem. Winds at the field were variable at the time below 10 KTS. We were very surprised to encounter the wake turbulence when we did.

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Original NASA ASRS Text

Title: AN F100 CREW, ON SHORT FINAL AT ORD, EXECUTED A GAR WHEN ENCOUNTERING WAKE TURB FROM THE PROCEEDING ACFT.

Narrative: APCH TO ORD RWY 9L FOLLOWING B777 5 MI IN TRAIL. WX 700 FT BROKEN, 3 MI VISIBILITY OR GREATER. FLEW APCH SLIGHTLY HIGH TO AVOID WAKE TURB. NO PROBS UNTIL IN CLOSE. SETTLED TO THE GS AT ABOUT 500 FT AGL. B777 DELAYED TURNING OFF THE RWY. AT 250 FT AGL WITH B777 JUST TURNING OFF, OUR ACFT ON SPD AND ON GS WITH FLAPS 42 DEGS WE HAD A SUDDEN L WING DROP OF 20-25 DEGS AND A 20 KT LOSS OF AIRSPD WITH SOME L YAW GAR INITIATED AND RECOVERY WAS UNEVENTFUL. NORMAL LNDG ON RWY 4 FOLLOWED. WE WERE VERY COMFORTABLE ON THE APCH AND SPACING DID NOT SEEM TO BE A PROB. WINDS AT THE FIELD WERE VARIABLE AT THE TIME BELOW 10 KTS. WE WERE VERY SURPRISED TO ENCOUNTER THE WAKE TURB WHEN WE DID.

Data retrieved from NASA's ASRS site as of July 2007 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.