Narrative:

Airlines flight approaching helena regional airport, helena, mt, on a flight from salt lake city most probably violated an altitude restriction during its approach to the airport. The flight under slc center radar control and on an IFR flight plan, was cleared to descend to 12000 ft. Upon leveloff at 12000 ft the flight was handed off to hln approach control (non-radar). Hln approach cleared the flight to 10000 ft and asked crew to report airport in sight. Neither pilot had ever landed at hln airport and were only familiar with the required special airport qualification video tape. Even though the crew had idented the approximately area of the airport, they were unable to positively identify the runways until 4 NM south of the airport. During this period of time, the crew continued to descend and had reached an altitude of 6500 MSL when they reported the airport in sight. Hln approach then cleared flight for a visual approach to runway 9 and asked crew to report leaving 10000. Crew replied with their actual altitude of 6500. Hln approach responded with 'report turn on to downwind'. Hln approach did not indicate that there was any problem with this altitude and there was no conflict with any other traffic. A normal visual approach and landing was made without further incident. Primary cause of incident: pilot's unfamiliarity with the hln airport. Even though the airport video tapes had been recently reviewed and the approximately location of the airport was known, the airport runways are extremely difficult to see as they blend in with the surrounding terrain. Contributing cause: both pilots were distracted not only by their attempts to visually locate the runways but also by ground proximity 'terrain' warnings which are normal when descending into hln. The result of the above was neither pilot realizing that they were not authorized to descend below their last assigned altitude until reporting the airport in sight and receiving clearance for the visual approach. Both pilots were focused on continuing a normal descent to the approximately location of the airport in order to set up for the visual traffic pattern and landing. Possible corrective actions: although hln is only a company designated special airport and is not particularly hazardous, it would be helpful to have a line check airman accompany a crew on their first entry in the case where neither crewmember has had an actual entry previously.

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Original NASA ASRS Text

Title: AN MLG ACR CREW IN VMC DSNDED BELOW THEIR ASSIGNED IFR ALT WHILE LOOKING FOR HLN ARPT. THIS WAS THEIR FIRST TRIP INTO HLN.

Narrative: AIRLINES FLT APCHING HELENA REGIONAL ARPT, HELENA, MT, ON A FLT FROM SALT LAKE CITY MOST PROBABLY VIOLATED AN ALT RESTRICTION DURING ITS APCH TO THE ARPT. THE FLT UNDER SLC CTR RADAR CTL AND ON AN IFR FLT PLAN, WAS CLRED TO DSND TO 12000 FT. UPON LEVELOFF AT 12000 FT THE FLT WAS HANDED OFF TO HLN APCH CTL (NON-RADAR). HLN APCH CLRED THE FLT TO 10000 FT AND ASKED CREW TO RPT ARPT IN SIGHT. NEITHER PLT HAD EVER LANDED AT HLN ARPT AND WERE ONLY FAMILIAR WITH THE REQUIRED SPECIAL ARPT QUALIFICATION VIDEO TAPE. EVEN THOUGH THE CREW HAD IDENTED THE APPROX AREA OF THE ARPT, THEY WERE UNABLE TO POSITIVELY IDENT THE RWYS UNTIL 4 NM S OF THE ARPT. DURING THIS PERIOD OF TIME, THE CREW CONTINUED TO DSND AND HAD REACHED AN ALT OF 6500 MSL WHEN THEY RPTED THE ARPT IN SIGHT. HLN APCH THEN CLRED FLT FOR A VISUAL APCH TO RWY 9 AND ASKED CREW TO RPT LEAVING 10000. CREW REPLIED WITH THEIR ACTUAL ALT OF 6500. HLN APCH RESPONDED WITH 'RPT TURN ON TO DOWNWIND'. HLN APCH DID NOT INDICATE THAT THERE WAS ANY PROBLEM WITH THIS ALT AND THERE WAS NO CONFLICT WITH ANY OTHER TFC. A NORMAL VISUAL APCH AND LNDG WAS MADE WITHOUT FURTHER INCIDENT. PRIMARY CAUSE OF INCIDENT: PLT'S UNFAMILIARITY WITH THE HLN ARPT. EVEN THOUGH THE ARPT VIDEO TAPES HAD BEEN RECENTLY REVIEWED AND THE APPROX LOCATION OF THE ARPT WAS KNOWN, THE ARPT RWYS ARE EXTREMELY DIFFICULT TO SEE AS THEY BLEND IN WITH THE SURROUNDING TERRAIN. CONTRIBUTING CAUSE: BOTH PLTS WERE DISTRACTED NOT ONLY BY THEIR ATTEMPTS TO VISUALLY LOCATE THE RWYS BUT ALSO BY GND PROX 'TERRAIN' WARNINGS WHICH ARE NORMAL WHEN DSNDING INTO HLN. THE RESULT OF THE ABOVE WAS NEITHER PLT REALIZING THAT THEY WERE NOT AUTHORIZED TO DSND BELOW THEIR LAST ASSIGNED ALT UNTIL RPTING THE ARPT IN SIGHT AND RECEIVING CLRNC FOR THE VISUAL APCH. BOTH PLTS WERE FOCUSED ON CONTINUING A NORMAL DSCNT TO THE APPROX LOCATION OF THE ARPT IN ORDER TO SET UP FOR THE VISUAL TFC PATTERN AND LNDG. POSSIBLE CORRECTIVE ACTIONS: ALTHOUGH HLN IS ONLY A COMPANY DESIGNATED SPECIAL ARPT AND IS NOT PARTICULARLY HAZARDOUS, IT WOULD BE HELPFUL TO HAVE A LINE CHK AIRMAN ACCOMPANY A CREW ON THEIR FIRST ENTRY IN THE CASE WHERE NEITHER CREWMEMBER HAS HAD AN ACTUAL ENTRY PREVIOUSLY.

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.