Narrative:

While descending thru FL280 at 200 FPM, (autoplt vertical speed engaged), ATC called, 'verify assigned altitude is FL290.' I and the 'pilot monitoring' looked at the altitude preselector, which read FL240. The 'pilot monitoring' replied, 'no, we were given FL240, and that is what I read back to you.' I had begun to instinctively arrest our descent rate, which reached a stabilized altitude of about FL274. I then noticed a 'target' on our TCASII display, about 4 mi away, 600 ft above our altitude, and quickly obtained a visual on the aircraft, as did the 'pilot monitoring.' perhaps separation (IFR) standards were compromised, but there was never any danger of a collision. Then, the kansas city controller told us to 'maintain FL240.' we acknowledged, and continued our descent. Then, ZKC said, 'recycle your transponder, I've lost your mode C.' (might this have been a 'cya' action?) we 'recycled,' and the remainder of the flight was uneventful. When we receive an altitude assignment, the 'pilot monitoring' sets the altitude pre selector, reads back the clearance to ATC, calls out the new altitude to the PF, and the 'PF' verbally acknowledges the assigned altitude. (Both pilots were listening to the ATC frequency, neither were distraction by other duties or passenger). The controller issued us the descent to FL240 in error. (We had previously been cleared to FL290.) we, as a crew of 2, acknowledged a 'descend to FL240' clearance, that was given to another aircraft, thinking and hearing it was for us. We read it back, and since we were not corrected or challenged, we complied with the descent. Quite possibly, the controller was working multiple aircraft, and did not hear our readback. Maybe the correct aircraft acknowledged the descent clearance also, and the controller did not hear us. Maybe, the controller was working more than one frequency, and did not hear our readback. (Another problem of multiple frequencys.) I have been in contact with the ZKC FSDO!

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Original NASA ASRS Text

Title: A CPR CAPT RPTED A READBACK HEARBACK PROB WITH ZKC WHICH RESULTED IN A TCASII TA.

Narrative: WHILE DSNDING THRU FL280 AT 200 FPM, (AUTOPLT VERT SPD ENGAGED), ATC CALLED, 'VERIFY ASSIGNED ALT IS FL290.' I AND THE 'PLT MONITORING' LOOKED AT THE ALT PRESELECTOR, WHICH READ FL240. THE 'PLT MONITORING' REPLIED, 'NO, WE WERE GIVEN FL240, AND THAT IS WHAT I READ BACK TO YOU.' I HAD BEGUN TO INSTINCTIVELY ARREST OUR DSCNT RATE, WHICH REACHED A STABILIZED ALT OF ABOUT FL274. I THEN NOTICED A 'TARGET' ON OUR TCASII DISPLAY, ABOUT 4 MI AWAY, 600 FT ABOVE OUR ALT, AND QUICKLY OBTAINED A VISUAL ON THE ACFT, AS DID THE 'PLT MONITORING.' PERHAPS SEPARATION (IFR) STANDARDS WERE COMPROMISED, BUT THERE WAS NEVER ANY DANGER OF A COLLISION. THEN, THE KANSAS CITY CTLR TOLD US TO 'MAINTAIN FL240.' WE ACKNOWLEDGED, AND CONTINUED OUR DSCNT. THEN, ZKC SAID, 'RECYCLE YOUR XPONDER, I'VE LOST YOUR MODE C.' (MIGHT THIS HAVE BEEN A 'CYA' ACTION?) WE 'RECYCLED,' AND THE REMAINDER OF THE FLT WAS UNEVENTFUL. WHEN WE RECEIVE AN ALT ASSIGNMENT, THE 'PLT MONITORING' SETS THE ALT PRE SELECTOR, READS BACK THE CLRNC TO ATC, CALLS OUT THE NEW ALT TO THE PF, AND THE 'PF' VERBALLY ACKNOWLEDGES THE ASSIGNED ALT. (BOTH PLTS WERE LISTENING TO THE ATC FREQ, NEITHER WERE DISTR BY OTHER DUTIES OR PAX). THE CTLR ISSUED US THE DSCNT TO FL240 IN ERROR. (WE HAD PREVIOUSLY BEEN CLRED TO FL290.) WE, AS A CREW OF 2, ACKNOWLEDGED A 'DSND TO FL240' CLRNC, THAT WAS GIVEN TO ANOTHER ACFT, THINKING AND HEARING IT WAS FOR US. WE READ IT BACK, AND SINCE WE WERE NOT CORRECTED OR CHALLENGED, WE COMPLIED WITH THE DSCNT. QUITE POSSIBLY, THE CTLR WAS WORKING MULTIPLE ACFT, AND DID NOT HEAR OUR READBACK. MAYBE THE CORRECT ACFT ACKNOWLEDGED THE DSCNT CLRNC ALSO, AND THE CTLR DID NOT HEAR US. MAYBE, THE CTLR WAS WORKING MORE THAN ONE FREQ, AND DID NOT HEAR OUR READBACK. (ANOTHER PROB OF MULTIPLE FREQS.) I HAVE BEEN IN CONTACT WITH THE ZKC FSDO!

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.