Narrative:

Boids 1 STAR to dfw, landing 36L. Landing direction had changed from 17/18 about 2 hours earlier. Usual clearance for south lndgs is to cross boids (bpr 108R/13) at 9000, north lndgs usually get clearance to be at 11,000 at 22 mi on same radial. At about 16,000 we were given clearance to cross boids at 9000, which was read back in full by first officer. About over bpr we were handed off to approach control, and first officer reported leaving 11,500 for 9000 with (ATIS). We were IMC almost all the time from about 16,000 MSL to 500 AGL. At about 23 mi on bpr 108R, approach controller asked us to confirm our altitude, to which first officer responded, 'nine thousand, assigned.' when told we had gotten that clearance from center, approach said, 'he shouldn't have done that, we've got northerly flow.' departures normally are kept at 10,000 until passing under arrs, then cleared to climb. We were obviously messing that up. I don't know if the approach or departure controller first noticed our altitude was wrong for traffic direction. As far as I know, there was no near midair collision. We are based at dfw and neither first officer nor I noticed the unusual altitude assignment, although we should have. We were briefing for a simulated CAT ii approach because WX had dropped fairly rapidly from 1500 overcast to 500 overcast, and I reminded crew that neither 36L nor this particular aircraft was authorized an actual CAT ii. Also, we had had a very slow operating anti-ice valve, and I had been talking to F/east about that, and had him call it in to maintenance prior to 10,000' MSL. We definitely were not shooting the breeze, and had not been since about FL240 because we knew the WX was getting worse and because of the anti-ice valve. I really don't think this was exactly a problem of 'readback/hearback'. For some reason, we were given the wrong altitude assignment, and it went undetected for over 20 mi.

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Original NASA ASRS Text

Title: MIXUP IN ALTS FOR ACR LGT ON BOIDS ONE STAR TO DFW.

Narrative: BOIDS 1 STAR TO DFW, LNDG 36L. LNDG DIRECTION HAD CHANGED FROM 17/18 ABOUT 2 HRS EARLIER. USUAL CLRNC FOR S LNDGS IS TO CROSS BOIDS (BPR 108R/13) AT 9000, N LNDGS USUALLY GET CLRNC TO BE AT 11,000 AT 22 MI ON SAME RADIAL. AT ABOUT 16,000 WE WERE GIVEN CLRNC TO CROSS BOIDS AT 9000, WHICH WAS READ BACK IN FULL BY F/O. ABOUT OVER BPR WE WERE HANDED OFF TO APCH CTL, AND F/O REPORTED LEAVING 11,500 FOR 9000 WITH (ATIS). WE WERE IMC ALMOST ALL THE TIME FROM ABOUT 16,000 MSL TO 500 AGL. AT ABOUT 23 MI ON BPR 108R, APCH CTLR ASKED US TO CONFIRM OUR ALT, TO WHICH F/O RESPONDED, 'NINE THOUSAND, ASSIGNED.' WHEN TOLD WE HAD GOTTEN THAT CLRNC FROM CENTER, APCH SAID, 'HE SHOULDN'T HAVE DONE THAT, WE'VE GOT NORTHERLY FLOW.' DEPS NORMALLY ARE KEPT AT 10,000 UNTIL PASSING UNDER ARRS, THEN CLRED TO CLIMB. WE WERE OBVIOUSLY MESSING THAT UP. I DON'T KNOW IF THE APCH OR DEP CTLR FIRST NOTICED OUR ALT WAS WRONG FOR TFC DIRECTION. AS FAR AS I KNOW, THERE WAS NO NMAC. WE ARE BASED AT DFW AND NEITHER F/O NOR I NOTICED THE UNUSUAL ALT ASSIGNMENT, ALTHOUGH WE SHOULD HAVE. WE WERE BRIEFING FOR A SIMULATED CAT II APCH BECAUSE WX HAD DROPPED FAIRLY RAPIDLY FROM 1500 OVCST TO 500 OVCST, AND I REMINDED CREW THAT NEITHER 36L NOR THIS PARTICULAR ACFT WAS AUTHORIZED AN ACTUAL CAT II. ALSO, WE HAD HAD A VERY SLOW OPERATING ANTI-ICE VALVE, AND I HAD BEEN TALKING TO F/E ABOUT THAT, AND HAD HIM CALL IT IN TO MAINT PRIOR TO 10,000' MSL. WE DEFINITELY WERE NOT SHOOTING THE BREEZE, AND HAD NOT BEEN SINCE ABOUT FL240 BECAUSE WE KNEW THE WX WAS GETTING WORSE AND BECAUSE OF THE ANTI-ICE VALVE. I REALLY DON'T THINK THIS WAS EXACTLY A PROBLEM OF 'READBACK/HEARBACK'. FOR SOME REASON, WE WERE GIVEN THE WRONG ALT ASSIGNMENT, AND IT WENT UNDETECTED FOR OVER 20 MI.

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.