Narrative:

Inbound to stl on the moduc arrival, we were descending by ZKC initially to FL240, but no further until the 64 DME out of stl. At that position we received and read back clearance to 8000' and reported leaving FL240. I reduced power and established nose down altitude. I wanted to start descent. Just as the aircraft was leaving FL240, the TCASII system announced, 'traffic,' so I looked at the display and saw a target 900' below us about 3-4 mi at 11 O'clock position. I leveled off at 23700' and looked at the TCASII display just as the TA turned into a red RA and TCASII announced, 'climb, climb,' calling for 1800-2000 FPM rate of climb. I raised the nose aggressively and applied climb power to rapidly return to FL240. We advised center that we had traffic below us and that I had taken evasive action due to TCASII RA conflict. Center said, 'maintain FL240,' after they had cleared us to 8000'. I asked center what the traffic was below us and they apparently did not wish to tell us. We were unable to see the conflicting aircraft due to a thick haze and poor visibility looking into the sun. If the other aircraft was level at FL230, I assume we got within 700' vertical to it as I leveled off at 23700. However, the TCASII projected our descent to indicate a conflict and called for corrective action. The TCASII system proved itself very effective on this trip.

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Original NASA ASRS Text

Title: ACR GIVEN DESCENT CLRNC AND RECEIVED A TCASII ALERT AS DESCENT STARTED. ACFT STOPPED DESCENT AND RETURNED TO LAST ASSIGNED ALT, QUESTIONED ATC, WHO SAID MAINTAIN ALT. APPEARS TO BE A SYSTEM ERROR.

Narrative: INBND TO STL ON THE MODUC ARR, WE WERE DSNDING BY ZKC INITIALLY TO FL240, BUT NO FURTHER UNTIL THE 64 DME OUT OF STL. AT THAT POS WE RECEIVED AND READ BACK CLRNC TO 8000' AND RPTED LEAVING FL240. I REDUCED PWR AND ESTABLISHED NOSE DOWN ALT. I WANTED TO START DSNT. JUST AS THE ACFT WAS LEAVING FL240, THE TCASII SYS ANNOUNCED, 'TFC,' SO I LOOKED AT THE DISPLAY AND SAW A TARGET 900' BELOW US ABOUT 3-4 MI AT 11 O'CLOCK POS. I LEVELED OFF AT 23700' AND LOOKED AT THE TCASII DISPLAY JUST AS THE TA TURNED INTO A RED RA AND TCASII ANNOUNCED, 'CLB, CLB,' CALLING FOR 1800-2000 FPM RATE OF CLB. I RAISED THE NOSE AGGRESSIVELY AND APPLIED CLB PWR TO RAPIDLY RETURN TO FL240. WE ADVISED CENTER THAT WE HAD TFC BELOW US AND THAT I HAD TAKEN EVASIVE ACTION DUE TO TCASII RA CONFLICT. CENTER SAID, 'MAINTAIN FL240,' AFTER THEY HAD CLRED US TO 8000'. I ASKED CENTER WHAT THE TFC WAS BELOW US AND THEY APPARENTLY DID NOT WISH TO TELL US. WE WERE UNABLE TO SEE THE CONFLICTING ACFT DUE TO A THICK HAZE AND POOR VISIBILITY LOOKING INTO THE SUN. IF THE OTHER ACFT WAS LEVEL AT FL230, I ASSUME WE GOT WITHIN 700' VERT TO IT AS I LEVELED OFF AT 23700. HOWEVER, THE TCASII PROJECTED OUR DSNT TO INDICATE A CONFLICT AND CALLED FOR CORRECTIVE ACTION. THE TCASII SYS PROVED ITSELF VERY EFFECTIVE ON THIS TRIP.

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.