Narrative:

Captain and first officer lost positional awareness during approach (ILS runway 3 cpr). Descended to 8500 ft MSL well prior to passing 193 degree radial on 29 DME arc. First officer was distraction with casper radio on VHF #1 and center on VHF #2. Jump seater queried the altitude and captain climbed back to 10400 ft. Subsequently cleared for visual approach. Supplemental information from acn 404310: arrival from the east, cleared to intercept 29 NM DME arc for the ILS runway 3 at cpr. Cleared for approach. Captain intercepted and turned onto arc, descended to 10400 ft. I became involved in talking to cpr radio and ZDV. FSS gave a quite lengthy list of NOTAMS and field conditions. At some point I dropped out of monitoring approach and concentrated on radios. Captain asked for my VOR radio to identify ddy 193 degree radial for stepdown fix. I complied and continued with radios. At some point, center wanted to know if we were complying with ILS runway 3 procedures. At this point, I was unsure where we were. We ended up at 8500 ft MSL, east of 193 degree radial, at about 25 NM. We climbed back to 10400 ft, headed for the 29 NM arc, I called airport in sight, cleared for visual. We had briefed for straight-in runway 3 not full procedure. Captain thought we were west of 193 degree radial when we weren't. Captain probably started towards airport, thus at 25 NM, not 29 NM. A full briefing, and my attention to approach, and my backing up captain would've avoided this incident. Communication with FSS should've ceased. Concurrence on my part should have proceeded descent to 8500 ft MSL.

Related reports:

Google
 

Original NASA ASRS Text

Title: ACR CREW DSNDED BELOW PROC ALT ON THE ARC TO THE ILS TO CPR, WY. BOTH CTLR AND JUMP SEAT RIDER NOTICED THE CFTT.

Narrative: CAPT AND FO LOST POSITIONAL AWARENESS DURING APCH (ILS RWY 3 CPR). DSNDED TO 8500 FT MSL WELL PRIOR TO PASSING 193 DEG RADIAL ON 29 DME ARC. FO WAS DISTR WITH CASPER RADIO ON VHF #1 AND CTR ON VHF #2. JUMP SEATER QUERIED THE ALT AND CAPT CLBED BACK TO 10400 FT. SUBSEQUENTLY CLRED FOR VISUAL APCH. SUPPLEMENTAL INFO FROM ACN 404310: ARR FROM THE E, CLRED TO INTERCEPT 29 NM DME ARC FOR THE ILS RWY 3 AT CPR. CLRED FOR APCH. CAPT INTERCEPTED AND TURNED ONTO ARC, DSNDED TO 10400 FT. I BECAME INVOLVED IN TALKING TO CPR RADIO AND ZDV. FSS GAVE A QUITE LENGTHY LIST OF NOTAMS AND FIELD CONDITIONS. AT SOME POINT I DROPPED OUT OF MONITORING APCH AND CONCENTRATED ON RADIOS. CAPT ASKED FOR MY VOR RADIO TO IDENT DDY 193 DEG RADIAL FOR STEPDOWN FIX. I COMPLIED AND CONTINUED WITH RADIOS. AT SOME POINT, CTR WANTED TO KNOW IF WE WERE COMPLYING WITH ILS RWY 3 PROCS. AT THIS POINT, I WAS UNSURE WHERE WE WERE. WE ENDED UP AT 8500 FT MSL, E OF 193 DEG RADIAL, AT ABOUT 25 NM. WE CLBED BACK TO 10400 FT, HEADED FOR THE 29 NM ARC, I CALLED ARPT IN SIGHT, CLRED FOR VISUAL. WE HAD BRIEFED FOR STRAIGHT-IN RWY 3 NOT FULL PROC. CAPT THOUGHT WE WERE W OF 193 DEG RADIAL WHEN WE WEREN'T. CAPT PROBABLY STARTED TOWARDS ARPT, THUS AT 25 NM, NOT 29 NM. A FULL BRIEFING, AND MY ATTN TO APCH, AND MY BACKING UP CAPT WOULD'VE AVOIDED THIS INCIDENT. COM WITH FSS SHOULD'VE CEASED. CONCURRENCE ON MY PART SHOULD HAVE PROCEEDED DSCNT TO 8500 FT MSL.

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.