ALTDEV DURING A NIGHT OP.

Narrative

CLRNC WAS TO CROSS 15 DME WNW OF BAE VOR AT 10000 FT MSL. I HAVE DONE THIS AT LEAST 100 TIMES IN PAST 20 YRS. ALWAYS THE SAME CLRNC; IN FACT I BRIEFED CREW IN ADVANCE WHAT THE CLRNC WOULD BE. AS BAE VOR WAS NOT IN OUR FLT PLAN OR INS (DELCO CAROUSEL) AND WE WERE CLRED TO THE VOR; AND ONLY 75 MI FROM IT; I DID NOT LOAD IT IN INS BUT WENT DIRECT WITH THE NAVAID RAW DATA. I WENT PRESENT; POS DIRECT TO THE MKE ARPT ON THE INS. SO NOW; I HAVE COCKPIT AND INST LIGHTS DIM; AND THE INS DISTANCE TO GO IS BRIGHTER THAN THE VOR DME READOUT. I PLANNED DSCNT TO MAKE RESTR; BUT DUE TO MY 'DIMINISHED' MENTAL CAPABILITIES (READ COMPLACENCY); I USED THE INS DISTANCE VICE VOR DME. ABOUT 20 DME BAE (CLRNC 5 MI TO GO) AND 15000 FT MSL; I FINALLY WOKE UP TO WHAT HAS HAPPENING. WE CALLED ZAU AND HE SAID TO DO THE BEST WE COULD. WE WERE ADVISED OF NO TFC CONFLICT. CAUSE OF ERROR WAS MENTAL (COMPLACENCY) ALL INST AND DME READING WERE CORRECT-I USED THE WRONG INFO DISPLAYED AND NATURALLY CAME UP WITH THE WRONG SOLUTION. SUPPLEMENTAL INFO FROM ACN #294478: A CONTRIBUTING FACTOR WAS THE FACT THAT THE FO AND SO WERE IN THE MILITARY TOGETHER; AND WERE SPENDING TOO MUCH TIME TELLING OLD STORIES; AND NOT ENOUGH TIME MONITORING THE DSCNT. EVEN THOUGH WE WERE ABOVE 10000 FT; THE XING RESTR WAS CRITICAL ENOUGH THAT WE SHOULD ALL HAVE BEEN PAYING MORE ATTN. HIGH RELIANCE ON INS ON A REGULAR BASIS LED US TO LEAVE VOR DME OUT OF OUR SCAN.