Narrative:

I was an first officer on airlines flight dispatched form slc to sun valley, identification (friedman memorial airport). The flight was IFR and uneventful during the departure and cruise phase. We were given a descent by ZLC about 40-50 mi out and were VMC soon after starting the descent. At about 20 mi we accepted a visual approach with the airport in sight. We immediately contacted hailey tower for advisories. Approximately 12-15 mi sse of the airport an object entered my peripheral vision from the right. I turned to look directly at the object and saw a blue and white single engine aircraft small aircraft, level and wbound on a collision course on the horizontal plane. I quickly pointed the aircraft out to the captain who was flying and he immediately saw the aircraft. Our sink rate was over 1000 FPM and carried us under the approaching aircraft with a separation of 100 to 200 ft. We immediately asked hailey tower if they were in contact with the aircraft and they responded 'negative.' while this was in controled airspace, conditions were VMC and no contact with ATC was required by the other aircraft, I observed no evasive action by the single engine airplane. He apparently was in cruise flight at approximately 8500 ft MSL. Several passenger in our aircraft observed the incident and mentioned it on the ground. During our descent prior to the incident, the small aircraft was patterned against the mountains northeast of our route. Patches of snow on the mountains may have reduced the contrast of the small aircraft against the backgnd. Nonetheless, the environment was 'see and avoid' for both aircraft, and I think the reason that the aircraft passed so close was a lack of proper scan and vigilance on the part of myself and the single engine pilot. My captain was prevented from observing the other aircraft by the long nose and windshield frame. The aircraft was an small aircraft. My captain and I agreed that presence of TCASII backup (assuming the other aircraft had a transponder) would have been beneficial.

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Original NASA ASRS Text

Title: ACR ON DSCNT HAS NMAC WITH SMA.

Narrative: I WAS AN FO ON AIRLINES FLT DISPATCHED FORM SLC TO SUN VALLEY, ID (FRIEDMAN MEMORIAL ARPT). THE FLT WAS IFR AND UNEVENTFUL DURING THE DEP AND CRUISE PHASE. WE WERE GIVEN A DSCNT BY ZLC ABOUT 40-50 MI OUT AND WERE VMC SOON AFTER STARTING THE DSCNT. AT ABOUT 20 MI WE ACCEPTED A VISUAL APCH WITH THE ARPT IN SIGHT. WE IMMEDIATELY CONTACTED HAILEY TWR FOR ADVISORIES. APPROX 12-15 MI SSE OF THE ARPT AN OBJECT ENTERED MY PERIPHERAL VISION FROM THE R. I TURNED TO LOOK DIRECTLY AT THE OBJECT AND SAW A BLUE AND WHITE SINGLE ENG ACFT SMA, LEVEL AND WBOUND ON A COLLISION COURSE ON THE HORIZ PLANE. I QUICKLY POINTED THE ACFT OUT TO THE CAPT WHO WAS FLYING AND HE IMMEDIATELY SAW THE ACFT. OUR SINK RATE WAS OVER 1000 FPM AND CARRIED US UNDER THE APCHING ACFT WITH A SEPARATION OF 100 TO 200 FT. WE IMMEDIATELY ASKED HAILEY TWR IF THEY WERE IN CONTACT WITH THE ACFT AND THEY RESPONDED 'NEGATIVE.' WHILE THIS WAS IN CTLED AIRSPACE, CONDITIONS WERE VMC AND NO CONTACT WITH ATC WAS REQUIRED BY THE OTHER ACFT, I OBSERVED NO EVASIVE ACTION BY THE SINGLE ENG AIRPLANE. HE APPARENTLY WAS IN CRUISE FLT AT APPROX 8500 FT MSL. SEVERAL PAX IN OUR ACFT OBSERVED THE INCIDENT AND MENTIONED IT ON THE GND. DURING OUR DSCNT PRIOR TO THE INCIDENT, THE SMA WAS PATTERNED AGAINST THE MOUNTAINS NE OF OUR RTE. PATCHES OF SNOW ON THE MOUNTAINS MAY HAVE REDUCED THE CONTRAST OF THE SMA AGAINST THE BACKGND. NONETHELESS, THE ENVIRONMENT WAS 'SEE AND AVOID' FOR BOTH ACFT, AND I THINK THE REASON THAT THE ACFT PASSED SO CLOSE WAS A LACK OF PROPER SCAN AND VIGILANCE ON THE PART OF MYSELF AND THE SINGLE ENG PLT. MY CAPT WAS PREVENTED FROM OBSERVING THE OTHER ACFT BY THE LONG NOSE AND WINDSHIELD FRAME. THE ACFT WAS AN SMA. MY CAPT AND I AGREED THAT PRESENCE OF TCASII BACKUP (ASSUMING THE OTHER ACFT HAD A XPONDER) WOULD HAVE BEEN BENEFICIAL.

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.