Narrative:

I believe the event occurred due to communications between ATC and an air carrier aircraft. While cruising at FL320 we received a TCAS TA on an aircraft at our 10 O'clock position. That aircraft continued to climb and leveled off at our altitude. ATC told air carrier to descend and at the same time we received a TCAS RA to climb. We followed the RA and advised ATC (when we were able). Air carrier crossed directly underneath us approximately 500 ft low. After clearing the conflict; we descended back to FL320. All aircraft and ATC were aware that the event happened through radio communications. Report was filed with flight managers immediately after landing. Every flight crew should be perfectly clear on ATC instructions.supplemental information from acn 733093: we were level at FL310 just south of tings intersection on J-29 when center cleared us to climb to FL330. I acknowledged the climb clearance; including the new altitude and our flight number. We initiated the climb in accordance with standard air carrier altitude change procedures. Our aircraft was light and climbing at a good rate (2500 ft min +/-). Shortly after passing FL320; center directed us to descend back to FL310. At about the same time as center directed us to descend we received an initial TCAS TA. The captain immediately disconnected the autoplt and started a descent back to FL310 in accordance with the ATC clearance. The TCAS TA changed to an RA at about the same time. It initially directed a climb but then immediately changed to a descend advisory at approximately 2000 ft per minute. The captain continued to comply with the ATC and TCAS directions and leveled the aircraft at FL310. The TCAS advised 'clear of traffic' and the TCAS target passed approximately 3 miles behind and 1000 ft above us moving right to left. We remained level at FL310 and soon thereafter were cleared back to FL330. I was using the cockpit speaker and hand microphone in compliance with 121 regulations and company procedure; while the captain was wearing a noise cancellation headset. We were both in agreement that we heard and accepted/responded to a climb clearance to FL330 for our flight number. The controller did not acknowledge our climb to FL330 readback; which was taken by us to mean that we read back the clearance correctly. We were later informed by our company that center had called and initially indicated that we had accepted an altitude change for another aircraft. Neither the captain nor myself suspected that we may have accepted the wrong clearance.

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Original NASA ASRS Text

Title: AN EMB145 PLT RPTS AN ACFT CLBING THROUGH HIS ALT CAUSED A TCAS RA WITH A 500 FT SEPARATION AT FL320. THE OTHER ACR PLT RPTS BEING CLEARED HIGHER.

Narrative: I BELIEVE THE EVENT OCCURRED DUE TO COMS BETWEEN ATC AND AN ACR ACFT. WHILE CRUISING AT FL320 WE RECEIVED A TCAS TA ON AN ACFT AT OUR 10 O'CLOCK POSITION. THAT ACFT CONTINUED TO CLB AND LEVELED OFF AT OUR ALT. ATC TOLD ACR TO DESCEND AND AT THE SAME TIME WE RECEIVED A TCAS RA TO CLB. WE FOLLOWED THE RA AND ADVISED ATC (WHEN WE WERE ABLE). ACR CROSSED DIRECTLY UNDERNEATH US APPROX 500 FT LOW. AFTER CLRING THE CONFLICT; WE DESCENDED BACK TO FL320. ALL ACFT AND ATC WERE AWARE THAT THE EVENT HAPPENED THROUGH RADIO COMS. RPT WAS FILED WITH FLT MANAGERS IMMEDIATELY AFTER LNDG. EVERY FLT CREW SHOULD BE PERFECTLY CLR ON ATC INSTRUCTIONS.SUPPLEMENTAL INFO FROM ACN 733093: WE WERE LEVEL AT FL310 JUST SOUTH OF TINGS INTXN ON J-29 WHEN CTR CLRED US TO CLB TO FL330. I ACKNOWLEDGED THE CLB CLRNC; INCLUDING THE NEW ALT AND OUR FLT NUMBER. WE INITIATED THE CLB IN ACCORDANCE WITH STANDARD ACR ALT CHANGE PROCS. OUR ACFT WAS LIGHT AND CLBING AT A GOOD RATE (2500 FT MIN +/-). SHORTLY AFTER PASSING FL320; CTR DIRECTED US TO DESCEND BACK TO FL310. AT ABOUT THE SAME TIME AS CTR DIRECTED US TO DESCEND WE RECEIVED AN INITIAL TCAS TA. THE CAPT IMMEDIATELY DISCONNECTED THE AUTOPLT AND STARTED A DESCENT BACK TO FL310 IN ACCORDANCE WITH THE ATC CLRNC. THE TCAS TA CHANGED TO AN RA AT ABOUT THE SAME TIME. IT INITIALLY DIRECTED A CLB BUT THEN IMMEDIATELY CHANGED TO A DESCEND ADVISORY AT APPROX 2000 FT PER MINUTE. THE CAPT CONTINUED TO COMPLY WITH THE ATC AND TCAS DIRECTIONS AND LEVELED THE ACFT AT FL310. THE TCAS ADVISED 'CLEAR OF TFC' AND THE TCAS TARGET PASSED APPROX 3 MILES BEHIND AND 1000 FT ABOVE US MOVING RIGHT TO LEFT. WE REMAINED LEVEL AT FL310 AND SOON THEREAFTER WERE CLRED BACK TO FL330. I WAS USING THE COCKPIT SPEAKER AND HAND MIKE IN COMPLIANCE WITH 121 REGULATIONS AND COMPANY PROC; WHILE THE CAPT WAS WEARING A NOISE CANCELLATION HEADSET. WE WERE BOTH IN AGREEMENT THAT WE HEARD AND ACCEPTED/RESPONDED TO A CLB CLRNC TO FL330 FOR OUR FLT NUMBER. THE CTLR DID NOT ACKNOWLEDGE OUR CLB TO FL330 READBACK; WHICH WAS TAKEN BY US TO MEAN THAT WE READ BACK THE CLRNC CORRECTLY. WE WERE LATER INFORMED BY OUR COMPANY THAT CTR HAD CALLED AND INITIALLY INDICATED THAT WE HAD ACCEPTED AN ALT CHANGE FOR ANOTHER ACFT. NEITHER THE CAPT NOR MYSELF SUSPECTED THAT WE MAY HAVE ACCEPTED THE WRONG CLRNC.

Data retrieved from NASA's ASRS site as of January 2009 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.