Narrative:

Location: 4 NM northwest of ord runway 32L intersection 10. On climb out to 5000 ft from ord runway 32L, first officer (PF) and I both heard a clearance to climb to 13000 ft. I did not hear our flight number, so I left 5000 ft in the altitude alert window while I verified with ATC. Verification that clearance was for another aircraft occurred as we climbed through 4600 ft at a high rate. Our altitude alert sounded as we topped out at 5380 ft before returning to 5000 ft. As a contributing factor, I deselected reduced climb power, resulting in full climb power at around 3500 ft. This complicated the first officer's task. Supplemental information from acn 452603: lesson learned is to fly the old clearance until you are sure of the new one and to fly the MCP altitude until PNF has made the change. Do not anticipate.

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Original NASA ASRS Text

Title: A B737 FLC CLBED ABOVE ASSIGNED ALT ON DEP FROM ORD.

Narrative: LOCATION: 4 NM NW OF ORD RWY 32L INTXN 10. ON CLBOUT TO 5000 FT FROM ORD RWY 32L, FO (PF) AND I BOTH HEARD A CLRNC TO CLB TO 13000 FT. I DID NOT HEAR OUR FLT NUMBER, SO I LEFT 5000 FT IN THE ALT ALERT WINDOW WHILE I VERIFIED WITH ATC. VERIFICATION THAT CLRNC WAS FOR ANOTHER ACFT OCCURRED AS WE CLBED THROUGH 4600 FT AT A HIGH RATE. OUR ALT ALERT SOUNDED AS WE TOPPED OUT AT 5380 FT BEFORE RETURNING TO 5000 FT. AS A CONTRIBUTING FACTOR, I DESELECTED REDUCED CLB PWR, RESULTING IN FULL CLB PWR AT AROUND 3500 FT. THIS COMPLICATED THE FO'S TASK. SUPPLEMENTAL INFO FROM ACN 452603: LESSON LEARNED IS TO FLY THE OLD CLRNC UNTIL YOU ARE SURE OF THE NEW ONE AND TO FLY THE MCP ALT UNTIL PNF HAS MADE THE CHANGE. DO NOT ANTICIPATE.

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.