Narrative:

Cleared to 12000 ft by ZAU and advised of VFR traffic lower in the vicinity of veena intersection, handed off to mke approach. He cleared us to '11 (eleven) thousand' and I acknowledged 11000 ft. TCASII showed traffic: 12 O'clock, 6 mi at 11000 ft. TCASII alerted at 3 NM, at 2 NM TCASII RA to descend. Descended 200 ft while visually acquiring a single engine cessna and the captain turned right to increase separation. I advised a very busy approach controller we were responding to a TCASII RA. He then cleared us to turn further right to 040 degrees and descend to 10000 ft. We called mke approach after landing and talked to the supervisor. He informed us the aircraft we had the conflict with was dropping parachutist and was VFR in a block altitude. He was also surprised the approach controller had given us 11000 ft as this was in the drop aircraft's block. Additionally, ZAU was supposed to give us a heading of 040 degrees to avoid the drop area prior to handing us off to approach. TCASII worked as advertised. Since we were exactly at the cessna's 6 O'clock position and level, without TCASII we wouldn't have seen him until dangerously close. I'll give the system a probable save.

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Original NASA ASRS Text

Title: FLC OF MLG DSNDED AND TURNED OFF OF ASSIGNED ALT IN RESPONSE TO A TCASII RA.

Narrative: CLRED TO 12000 FT BY ZAU AND ADVISED OF VFR TFC LOWER IN THE VICINITY OF VEENA INTXN, HANDED OFF TO MKE APCH. HE CLRED US TO '11 (ELEVEN) THOUSAND' AND I ACKNOWLEDGED 11000 FT. TCASII SHOWED TFC: 12 O'CLOCK, 6 MI AT 11000 FT. TCASII ALERTED AT 3 NM, AT 2 NM TCASII RA TO DSND. DSNDED 200 FT WHILE VISUALLY ACQUIRING A SINGLE ENG CESSNA AND THE CAPT TURNED R TO INCREASE SEPARATION. I ADVISED A VERY BUSY APCH CTLR WE WERE RESPONDING TO A TCASII RA. HE THEN CLRED US TO TURN FURTHER R TO 040 DEGS AND DSND TO 10000 FT. WE CALLED MKE APCH AFTER LNDG AND TALKED TO THE SUPVR. HE INFORMED US THE ACFT WE HAD THE CONFLICT WITH WAS DROPPING PARACHUTIST AND WAS VFR IN A BLOCK ALT. HE WAS ALSO SURPRISED THE APCH CTLR HAD GIVEN US 11000 FT AS THIS WAS IN THE DROP ACFT'S BLOCK. ADDITIONALLY, ZAU WAS SUPPOSED TO GIVE US A HDG OF 040 DEGS TO AVOID THE DROP AREA PRIOR TO HANDING US OFF TO APCH. TCASII WORKED AS ADVERTISED. SINCE WE WERE EXACTLY AT THE CESSNA'S 6 O'CLOCK POS AND LEVEL, WITHOUT TCASII WE WOULDN'T HAVE SEEN HIM UNTIL DANGEROUSLY CLOSE. I'LL GIVE THE SYS A PROBABLE SAVE.

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.