Narrative:

The flight departed boeing field in seattle, wa. Another crew began the flight and then the captain and myself took over with about 2 hours remaining in the flight. Approaching cold bay, ak, we were cleared direct to the milam intersection. Zan then cleared us to maintain 10000 ft until milam, cleared localizer DME (back course) runway 32 at cold bay. The captain, who was the PF, then briefed the approach. While reviewing the approach, I mistook the cdb/110 degrees/30 DME fix for milam. The captain made the same mistake. Prior to reaching milam, zan advised us to change to advisory frequency. We then contacted cold bay radio and advised them that we were crossing milam on the approach. Since we had been told to maintain 10000 ft until milam, and we had mistaken the 110 degree radial fix for milam, the captain called for 5500 ft to be set in the altitude alerter upon crossing milam. In fact, we should have waited until crossing the cdb 110 degree radial before changing the altitude. We began our descent at milam. As we were descending through approximately 6500 ft, and prior to the 110 degree radial fix, cold bay radio told us that zan advised that we were to maintain 10000 ft until crossing the cdb/110 degrees/30 DME fix. We acknowledged and the captain immediately began a climb. At this time we were within approximately 5 NM of the 110 degree radial fix. We continued to climb until crossing the 110 degree radial fix, at which time we descended to 5500 ft. The remainder of the approach was without incident. This situation was caused when both pilots mistook the cdb/110 degrees/30 DME fix for the IAF milam. The situation has been discussed with our chief pilot. All other company pilots are aware that this situation had the potential of a dangerous and deadly outcome. The crew's approach briefing ensure that all crew members are fully prepared for the appropriate approach. Care must be taken to ensure that the approach is understood and both crew members agree on the proper approach procedures. Supplemental information from acn 633512: center cleared the flight direct to cold bay. Closer to cold bay and after ATIS had been received center asked if I preferred the procedure turn or the DME arc for runway 32 cold bay. I elected the DME arc. Center then cleared the flight direct milam, maintain 10000 ft until milam. Somehow I misconstrued the 5500 ft in bold print as the altitude to be at crossing the 110 degree radial cdb. At milam, center advised us to contact cold bay advisory. I instructed the first officer to put 5500 ft in the altitude alerter and began descent. During the descent and prior to reaching the 110 degree radial advisory called to say center advises you to maintain 10000 ft until crossing the 110 degree radial. The altitude was approximately 6500 ft when an immediate climb was initiated towards 10000 ft. After crossing the 110 degree radial, 30 DME descent was begun for the completion of the approach without further incident. On the ground the first officer and I discussed the situation. I had not thoroughly reviewed the approach. Both of us missed the altitude for crossing the 110 degree radial.

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Original NASA ASRS Text

Title: HS125 CREW DSNDED BELOW THE CLRED ALT AT MILAM GOING INTO PACD.

Narrative: THE FLT DEPARTED BOEING FIELD IN SEATTLE, WA. ANOTHER CREW BEGAN THE FLT AND THEN THE CAPT AND MYSELF TOOK OVER WITH ABOUT 2 HRS REMAINING IN THE FLT. APCHING COLD BAY, AK, WE WERE CLRED DIRECT TO THE MILAM INTXN. ZAN THEN CLRED US TO MAINTAIN 10000 FT UNTIL MILAM, CLRED LOC DME (BACK COURSE) RWY 32 AT COLD BAY. THE CAPT, WHO WAS THE PF, THEN BRIEFED THE APCH. WHILE REVIEWING THE APCH, I MISTOOK THE CDB/110 DEGS/30 DME FIX FOR MILAM. THE CAPT MADE THE SAME MISTAKE. PRIOR TO REACHING MILAM, ZAN ADVISED US TO CHANGE TO ADVISORY FREQ. WE THEN CONTACTED COLD BAY RADIO AND ADVISED THEM THAT WE WERE XING MILAM ON THE APCH. SINCE WE HAD BEEN TOLD TO MAINTAIN 10000 FT UNTIL MILAM, AND WE HAD MISTAKEN THE 110 DEG RADIAL FIX FOR MILAM, THE CAPT CALLED FOR 5500 FT TO BE SET IN THE ALT ALERTER UPON XING MILAM. IN FACT, WE SHOULD HAVE WAITED UNTIL XING THE CDB 110 DEG RADIAL BEFORE CHANGING THE ALT. WE BEGAN OUR DSCNT AT MILAM. AS WE WERE DSNDING THROUGH APPROX 6500 FT, AND PRIOR TO THE 110 DEG RADIAL FIX, COLD BAY RADIO TOLD US THAT ZAN ADVISED THAT WE WERE TO MAINTAIN 10000 FT UNTIL XING THE CDB/110 DEGS/30 DME FIX. WE ACKNOWLEDGED AND THE CAPT IMMEDIATELY BEGAN A CLB. AT THIS TIME WE WERE WITHIN APPROX 5 NM OF THE 110 DEG RADIAL FIX. WE CONTINUED TO CLB UNTIL XING THE 110 DEG RADIAL FIX, AT WHICH TIME WE DSNDED TO 5500 FT. THE REMAINDER OF THE APCH WAS WITHOUT INCIDENT. THIS SIT WAS CAUSED WHEN BOTH PLTS MISTOOK THE CDB/110 DEGS/30 DME FIX FOR THE IAF MILAM. THE SIT HAS BEEN DISCUSSED WITH OUR CHIEF PLT. ALL OTHER COMPANY PLTS ARE AWARE THAT THIS SIT HAD THE POTENTIAL OF A DANGEROUS AND DEADLY OUTCOME. THE CREW'S APCH BRIEFING ENSURE THAT ALL CREW MEMBERS ARE FULLY PREPARED FOR THE APPROPRIATE APCH. CARE MUST BE TAKEN TO ENSURE THAT THE APCH IS UNDERSTOOD AND BOTH CREW MEMBERS AGREE ON THE PROPER APCH PROCS. SUPPLEMENTAL INFO FROM ACN 633512: CTR CLRED THE FLT DIRECT TO COLD BAY. CLOSER TO COLD BAY AND AFTER ATIS HAD BEEN RECEIVED CTR ASKED IF I PREFERRED THE PROC TURN OR THE DME ARC FOR RWY 32 COLD BAY. I ELECTED THE DME ARC. CTR THEN CLRED THE FLT DIRECT MILAM, MAINTAIN 10000 FT UNTIL MILAM. SOMEHOW I MISCONSTRUED THE 5500 FT IN BOLD PRINT AS THE ALT TO BE AT XING THE 110 DEG RADIAL CDB. AT MILAM, CTR ADVISED US TO CONTACT COLD BAY ADVISORY. I INSTRUCTED THE FO TO PUT 5500 FT IN THE ALT ALERTER AND BEGAN DSCNT. DURING THE DSCNT AND PRIOR TO REACHING THE 110 DEG RADIAL ADVISORY CALLED TO SAY CTR ADVISES YOU TO MAINTAIN 10000 FT UNTIL XING THE 110 DEG RADIAL. THE ALT WAS APPROX 6500 FT WHEN AN IMMEDIATE CLB WAS INITIATED TOWARDS 10000 FT. AFTER XING THE 110 DEG RADIAL, 30 DME DSCNT WAS BEGUN FOR THE COMPLETION OF THE APCH WITHOUT FURTHER INCIDENT. ON THE GND THE FO AND I DISCUSSED THE SIT. I HAD NOT THOROUGHLY REVIEWED THE APCH. BOTH OF US MISSED THE ALT FOR XING THE 110 DEG RADIAL.

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.