Narrative:

On VMC ILS runway 31C circle-to-land runway 22L at mdw, approximately 2 mi final, a target showed on TCASII at our altitude and approximately 1 mi away. RA called for climb. We climbed, saw no traffic. Advised ATC suspected a false target. ATC had no reported traffic after RA. Continued normal operations.

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Original NASA ASRS Text

Title: FLC OF A B737-200 STOPPED ILS APCH AND CLBED IN RESPONSE TO A TCASII RA. NO TFC OBSERVED AND TWR SHOWED NO OTHER CONFLICTING TFC.

Narrative: ON VMC ILS RWY 31C CIRCLE-TO-LAND RWY 22L AT MDW, APPROX 2 MI FINAL, A TARGET SHOWED ON TCASII AT OUR ALT AND APPROX 1 MI AWAY. RA CALLED FOR CLB. WE CLBED, SAW NO TFC. ADVISED ATC SUSPECTED A FALSE TARGET. ATC HAD NO RPTED TFC AFTER RA. CONTINUED NORMAL OPS.

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.