Narrative:

I was working sector 54 radar when aircraft X checked on descending to FL240. I gave the standard crossing for the qball STAR of 11000 ft and 2350 KTS. When aircraft X read back the clearance, it was around shift change, therefore, the area was full of people coming in and the noise level was above average due to new controllers signing in to work and relieving other position. Aircraft X read back 10000 ft and 250 KTS and myself and 2 other controllers thought he read back 11000 ft and 250 KTS. About 5 mins later, I had an overflt aircraft at 10000 ft crossing the arrival route. I issued aircraft X the traffic and he acknowledged it, but when I noticed him at 10800 ft, I told him to maintain 11000 ft and he complied. Supplemental information from acn 642377: I was off communication #1 getting ATIS, gate arrival information. My first officer took descent clearance while I was off-line. Controller issued a crossing (after center reviewed tapes) of 11000 ft/250 KIAS at qball. My first officer read back 10000 ft/250 KTS at qball. It was uncorrected by ATC. At approximately 11000 ft MSL, controller advised us to maintain 11000 ft. Descent was arrested by about 10720 ft and we returned to 11000 ft. On ground, I was asked to call center about a possible deviation. I called. They said tapes were reviewed and it was controller error. My first officer was new to flying the line. He made an honest mistake, not questioning what he thought was a properly issued clearance. STAR probably could have been reviewed more thoroughly to determine what proper crossing altitude should have been at that point. We could have queried ATC as to the proper altitude. I finished on communication #2 just about the time we were approaching 11000 ft MSL. If I had finished earlier, I might have had time to ask ATC or first officer about our assigned altitude.

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Original NASA ASRS Text

Title: ZKC CTLR MISSED INCORRECT ALT READBACK ON DSCNT CLRNC AND EXPERIENCED OPERROR AT APPROX 10000 FT.

Narrative: I WAS WORKING SECTOR 54 RADAR WHEN ACFT X CHKED ON DSNDING TO FL240. I GAVE THE STANDARD XING FOR THE QBALL STAR OF 11000 FT AND 2350 KTS. WHEN ACFT X READ BACK THE CLRNC, IT WAS AROUND SHIFT CHANGE, THEREFORE, THE AREA WAS FULL OF PEOPLE COMING IN AND THE NOISE LEVEL WAS ABOVE AVERAGE DUE TO NEW CTLRS SIGNING IN TO WORK AND RELIEVING OTHER POS. ACFT X READ BACK 10000 FT AND 250 KTS AND MYSELF AND 2 OTHER CTLRS THOUGHT HE READ BACK 11000 FT AND 250 KTS. ABOUT 5 MINS LATER, I HAD AN OVERFLT ACFT AT 10000 FT XING THE ARR RTE. I ISSUED ACFT X THE TFC AND HE ACKNOWLEDGED IT, BUT WHEN I NOTICED HIM AT 10800 FT, I TOLD HIM TO MAINTAIN 11000 FT AND HE COMPLIED. SUPPLEMENTAL INFO FROM ACN 642377: I WAS OFF COM #1 GETTING ATIS, GATE ARR INFO. MY FO TOOK DSCNT CLRNC WHILE I WAS OFF-LINE. CTLR ISSUED A XING (AFTER CTR REVIEWED TAPES) OF 11000 FT/250 KIAS AT QBALL. MY FO READ BACK 10000 FT/250 KTS AT QBALL. IT WAS UNCORRECTED BY ATC. AT APPROX 11000 FT MSL, CTLR ADVISED US TO MAINTAIN 11000 FT. DSCNT WAS ARRESTED BY ABOUT 10720 FT AND WE RETURNED TO 11000 FT. ON GND, I WAS ASKED TO CALL CTR ABOUT A POSSIBLE DEV. I CALLED. THEY SAID TAPES WERE REVIEWED AND IT WAS CTLR ERROR. MY FO WAS NEW TO FLYING THE LINE. HE MADE AN HONEST MISTAKE, NOT QUESTIONING WHAT HE THOUGHT WAS A PROPERLY ISSUED CLRNC. STAR PROBABLY COULD HAVE BEEN REVIEWED MORE THOROUGHLY TO DETERMINE WHAT PROPER XING ALT SHOULD HAVE BEEN AT THAT POINT. WE COULD HAVE QUERIED ATC AS TO THE PROPER ALT. I FINISHED ON COM #2 JUST ABOUT THE TIME WE WERE APCHING 11000 FT MSL. IF I HAD FINISHED EARLIER, I MIGHT HAVE HAD TIME TO ASK ATC OR FO ABOUT OUR ASSIGNED ALT.

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.