Narrative:

I was flying the ILS to 27L at ord via the flight director and autoplt when we encountered windshear. Our first indication in smooth air on the GS was a 40 KT increase in airspeed at about 3000 ft MSL. Immediately I noticed our sink rate go to 1500 FPM down followed by light chop to moderate almost severe turbulence. I disconnected the autoplt and initiated a go around following our windshear procedures. The first officer told ATC we were going around and of our condition. The aircraft was initially slow to respond to inputs and approximately 500 ft was lost. At first the ATC controller told us to level at 4000 ft and we were at 4500 when he immediately cleared us to 5000 ft. On level off we drifted to 5300 ft as we were still in pretty choppy air, the controller cleared us to 6000 ft at which time we were through the shear and were able to maintain aircraft control. I feel the controllers did an outstanding job in assisting us in altitude and maneuvering around the cells to the north of the airport. I feel the situation was an insidious set up in that the thunderstorms were 5-10 mi north of the field and no other aircraft were reporting any problems and the ride was smooth until we hit the shear. I feel that the windshear simulator training we go through on recognition and recovery was invaluable in our maneuvering once we encountered the shear. The lesson learned here is that even though everyone else is landing it doesn't mean that you are assured a landing. In other words I have a much healthier respect for thunderstorms and their effect in a terminal area.

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Original NASA ASRS Text

Title: ACR MLG ENCOUNTERED WIND SHEAR ON APCH TO ORD 27L. ALT AND AIRSPD FLUCTUATIONS CAUSED FLC TO GAR.

Narrative: I WAS FLYING THE ILS TO 27L AT ORD VIA THE FLT DIRECTOR AND AUTOPLT WHEN WE ENCOUNTERED WINDSHEAR. OUR FIRST INDICATION IN SMOOTH AIR ON THE GS WAS A 40 KT INCREASE IN AIRSPD AT ABOUT 3000 FT MSL. IMMEDIATELY I NOTICED OUR SINK RATE GO TO 1500 FPM DOWN FOLLOWED BY LIGHT CHOP TO MODERATE ALMOST SEVERE TURB. I DISCONNECTED THE AUTOPLT AND INITIATED A GAR FOLLOWING OUR WINDSHEAR PROCS. THE FO TOLD ATC WE WERE GOING AROUND AND OF OUR CONDITION. THE ACFT WAS INITIALLY SLOW TO RESPOND TO INPUTS AND APPROX 500 FT WAS LOST. AT FIRST THE ATC CTLR TOLD US TO LEVEL AT 4000 FT AND WE WERE AT 4500 WHEN HE IMMEDIATELY CLRED US TO 5000 FT. ON LEVEL OFF WE DRIFTED TO 5300 FT AS WE WERE STILL IN PRETTY CHOPPY AIR, THE CTLR CLRED US TO 6000 FT AT WHICH TIME WE WERE THROUGH THE SHEAR AND WERE ABLE TO MAINTAIN ACFT CTL. I FEEL THE CTLRS DID AN OUTSTANDING JOB IN ASSISTING US IN ALT AND MANEUVERING AROUND THE CELLS TO THE N OF THE ARPT. I FEEL THE SITUATION WAS AN INSIDIOUS SET UP IN THAT THE TSTMS WERE 5-10 MI N OF THE FIELD AND NO OTHER ACFT WERE RPTING ANY PROBLEMS AND THE RIDE WAS SMOOTH UNTIL WE HIT THE SHEAR. I FEEL THAT THE WINDSHEAR SIMULATOR TRAINING WE GO THROUGH ON RECOGNITION AND RECOVERY WAS INVALUABLE IN OUR MANEUVERING ONCE WE ENCOUNTERED THE SHEAR. THE LESSON LEARNED HERE IS THAT EVEN THOUGH EVERYONE ELSE IS LNDG IT DOESN'T MEAN THAT YOU ARE ASSURED A LNDG. IN OTHER WORDS I HAVE A MUCH HEALTHIER RESPECT FOR TSTMS AND THEIR EFFECT IN A TERMINAL AREA.

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.