Narrative:

The radar sector was very busy with numerous departures climbing east off of detroit and arrs to cleveland from the northwest. Also thunderstorms were impacting the surrounding airspace with several aircraft deviating. A cleveland inbound, cpr Y was descending to 160 along V103. Air carrier X departed dtw and checked in climbing to 103. He was reclred to 150 and turned to facilitate lateral separation from cpr Y. He acknowledged. Air carrier Z was cleared to FL240 several moments later. Air carrier X took this clearance and climbed through 150 resulting in lost separation with cpr Y. When this was observed, air carrier X was reclred to 150 and both aircraft were issued turns. Separation was reestablished and both aircraft proceeded on course. The primary factor was a missed readback and a wrong clearance taken. Contributing to this was the WX, workload and similar call signs. Supplemental information from acn 215060: air carrier X level at 15000 ft. Several aircraft, including us, deviating around thunderstorms. There was a lot of confusion, many special requests, and several aircraft with similar call signs. The first officer acknowledged a clearance to FL240. Just prior to 16000 ft the ATC controller told us to go back to 15000 ft. It was not clear if we had accepted another aircraft's clearance to 24000 or if the controller had given it to us by mistake. A couple mins later the same controller gave us a clearance to FL230. Again after we were about to pass 16000 ft he cancelled the clearance and told us to maintain 16000 ft. We looked for (both visually and with TCASII) any conflicting traffic and saw none.

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Original NASA ASRS Text

Title: ACR X (SAME COMPANY SIMILAR CALL SIGN AS ACR Z) READ BACK ACR Z CLRNC. UNAUTHORIZED CLB THROUGH OCCUPIED ALT HAD LTSS FROM CPR Y. SYS ERROR.

Narrative: THE RADAR SECTOR WAS VERY BUSY WITH NUMEROUS DEPS CLBING E OFF OF DETROIT AND ARRS TO CLEVELAND FROM THE NW. ALSO TSTMS WERE IMPACTING THE SURROUNDING AIRSPACE WITH SEVERAL ACFT DEVIATING. A CLEVELAND INBOUND, CPR Y WAS DSNDING TO 160 ALONG V103. ACR X DEPARTED DTW AND CHKED IN CLBING TO 103. HE WAS RECLRED TO 150 AND TURNED TO FACILITATE LATERAL SEPARATION FROM CPR Y. HE ACKNOWLEDGED. ACR Z WAS CLRED TO FL240 SEVERAL MOMENTS LATER. ACR X TOOK THIS CLRNC AND CLBED THROUGH 150 RESULTING IN LOST SEPARATION WITH CPR Y. WHEN THIS WAS OBSERVED, ACR X WAS RECLRED TO 150 AND BOTH ACFT WERE ISSUED TURNS. SEPARATION WAS REESTABLISHED AND BOTH ACFT PROCEEDED ON COURSE. THE PRIMARY FACTOR WAS A MISSED READBACK AND A WRONG CLRNC TAKEN. CONTRIBUTING TO THIS WAS THE WX, WORKLOAD AND SIMILAR CALL SIGNS. SUPPLEMENTAL INFO FROM ACN 215060: ACR X LEVEL AT 15000 FT. SEVERAL ACFT, INCLUDING US, DEVIATING AROUND TSTMS. THERE WAS A LOT OF CONFUSION, MANY SPECIAL REQUESTS, AND SEVERAL ACFT WITH SIMILAR CALL SIGNS. THE FO ACKNOWLEDGED A CLRNC TO FL240. JUST PRIOR TO 16000 FT THE ATC CTLR TOLD US TO GO BACK TO 15000 FT. IT WAS NOT CLR IF WE HAD ACCEPTED ANOTHER ACFT'S CLRNC TO 24000 OR IF THE CTLR HAD GIVEN IT TO US BY MISTAKE. A COUPLE MINS LATER THE SAME CTLR GAVE US A CLRNC TO FL230. AGAIN AFTER WE WERE ABOUT TO PASS 16000 FT HE CANCELLED THE CLRNC AND TOLD US TO MAINTAIN 16000 FT. WE LOOKED FOR (BOTH VISUALLY AND WITH TCASII) ANY CONFLICTING TFC AND SAW NONE.

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.