BIRTH OF AN ALT BUST.

Narrative

PASSING OVER CVG; IND ARTCC ISSUED A DSCNT CLRNC FROM FL180 TO 16000 MSI. AN ADDITIONAL CLRNC WAS INTERP BY COCKPIT CREW TO DSND TO 13000 MSL; WHICH WAS ACKNOWLEDGED BY IND CTR. AMID THE DSCNT FOLLOWING THIS SEGMENT OF FLT; WE WERE HANDED OFF TO SDF APCH FOR AN UNEVENTFUL APCH AND LNDG -- ALL REGIMES OF FLT APPEARED NORMAL. AFTER RETURNING TO CLEVELAND; OH; (CREW DOMICIK) 2.5 HRS LATER; WE WERE INFORMED BY COMPANY DISPATCH TO CALL IND ARTCC AND SPEAK WITH MR. X. WE WERE THEN INFORMED THAT OUR CLRNC LIMIT WAS ONLY 16000 AND NOT 13000 AS INTERPRETED BY CREW. WE WERE INFORMED BY MR. X THAT QUALITY ASSURANCE WAS REVIEWING THE TAPES. MR. X CLAIMED THERE WAS A TFC CONFLICT OF APPROX 3.5 MI SEPARATION ; BUT EMPHASIZED IT WAS NOT A SERIOUS EVENT. WE WERE NEVER INFORMED DURING THE FLT THAT THERE WAS A PROB; NOR DID WE FEEL THAT THERE WAS ANY ABNORMALITY DURING FLT. I FEEL THERE WERE 4 ITEMS THAT CONTRIBUTED TO OUR ALLEGED ERROR: I AS CAPT ONLY RECEIVED A FEW HRS OF SLEEP THE NIGHT BEFORE; POSSIBLY AFFECTING ATTN TO DETAILS. FO MAY HAVE BEEN ON COM #2 RECEIVING ATIS OR MAKING COMPANY IN-RANGE CALL. BOTH PLTS MAY HAVE NOT VERIFIED ALT SET IN ALT ALERTER SYS. OUR ACFT DID NOT HAVE A TCASII SYS INSTALLED; WHICH WOULD HAVE ALERTED US OF A POSSIBLE TFC CONFLICT. SUPPLEMENTAL INFO FROM ACN 271718: I ALSO REMEMBER NEEDING TO GET THE SDF ATIS AROUND THE CVG AREA DUE TO OUR GND SPD OF 360 KTS. I ALSO TRIED TO REACH OUR SDF OPS AFTER GETTING THE ATIS. WE WERE QUITE EARLY DUE TO THE TAILWINDS AND I WAS UNABLE TO REACH THEM THE FIRST TIME. I TRIED AGAIN A LITTLE LATER AND THEN 1 MORE TIME BEFORE GETTING THEM. IT IS QUITE POSSIBLE THAT I WAS OFF THE FREQ DURING THE TIME OF THE DSCNT. I AM ALMOST SURE THAT I WAS NOT ON DURING A FREQ CHANGE FROM 1 IND TO ANOTHER IND FREQ. I BELIEVE THIS COULD HAVE BEEN A CONTRIBUTING FACTOR TO A DOUBLE CHK OF THE ALT. ALSO; A TCASII WOULD HAVE WARNED US OF THE TFC.