Narrative:

After clearing the WX in the pasco area, we asked for and received clearance to operate eastbound at 10000 ft, as that would place us above a lower building cloud deck, and still allow us to fly without using our oxygen. It was approximately during this time frame that ZSE started giving us unknown traffic at our 7 O'clock position gaining on us slowly. We both kept searching for the traffic, but did not see it. The traffic kept climbing, and the controller suggested a climb for us to 10500 ft, which we did. As we were climbing through 10200 ft we first saw the traffic. The traffic's reported mode C altitude was 9800 ft. I estimate the small aircraft Y passed directly underneath us with approximately 400 ft separation with a heading about 60 degrees south of ours. It was at approximately this time frame that we both observed the small aircraft Y fly next to the cloud banks off to our south. It is my professional opinion that there is no possible way for that small aircraft to remain in VFR conditions reference the distance from cloud criteria in far 91.155(a). After arrival at twin falls, we asked ground control where the other small aircraft had parked. As we climbed out of our plane, I asked the line boy if he knew where the crew of subject small aircraft was, and he pointed to a couple walking across the ramp towards the terminal. I then jogged over to them, and asked if they had just flown in from the seattle area. Their response was 'yes.' I then said we needed to talk about our near miss and possible FAA violations. The gentleman told me to go talk to the FAA, and turned around to continue his walk to the terminal. I returned to our aircraft to gather my paperwork, and went into the FBO to call the FAA. Far 91.113(a): this aircraft did not appear to 'pass over, under, or ahead of it unless well clear.' I do not consider a mode C readout between aircraft of 400 ft to be 'well clear.' far 91.113(F): this aircraft converged twice from our left side. The first time was during the conflict alert given by ZSE described above, the second was as we approached baker VOR. Far 91.155(a): after our near miss, we both watched this aircraft approach the clouds within 1/2 mi laterally and 300 ft above. Far 91.159(a): I believe it is the intent of this far to fly at the proper altitude for direction of flight while over 3000 ft AGL. Far 91.113(a): at least once, both my passenger and myself felt endangered by the flight path of small aircraft Y as the TA was issued. I further feel that other unknown aircraft could have been endangered as the small aircraft passed next to the clouds, especially when it was above 10000 ft. He could have filed IFR, if he was instrument rated, equipped, and qualified. VFR flight following service, while not required, would have been safer than continuing on without talking to anyone. A cruise altitude of 11500 ft would have put small aircraft Y above known WX and traffic. It also would have allowed the small aircraft to fly at a proper altitude for direction of flight.

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Original NASA ASRS Text

Title: ONE SMA PLT COMPLAINS OF OTHER SMA PLT BEHAVIOR UNPROFESSIONAL ATTITUDE IN NMAC INCIDENT.

Narrative: AFTER CLRING THE WX IN THE PASCO AREA, WE ASKED FOR AND RECEIVED CLRNC TO OPERATE EBOUND AT 10000 FT, AS THAT WOULD PLACE US ABOVE A LOWER BUILDING CLOUD DECK, AND STILL ALLOW US TO FLY WITHOUT USING OUR OXYGEN. IT WAS APPROX DURING THIS TIME FRAME THAT ZSE STARTED GIVING US UNKNOWN TFC AT OUR 7 O'CLOCK POS GAINING ON US SLOWLY. WE BOTH KEPT SEARCHING FOR THE TFC, BUT DID NOT SEE IT. THE TFC KEPT CLBING, AND THE CTLR SUGGESTED A CLB FOR US TO 10500 FT, WHICH WE DID. AS WE WERE CLBING THROUGH 10200 FT WE FIRST SAW THE TFC. THE TFC'S RPTED MODE C ALT WAS 9800 FT. I ESTIMATE THE SMA Y PASSED DIRECTLY UNDERNEATH US WITH APPROX 400 FT SEPARATION WITH A HDG ABOUT 60 DEGS S OF OURS. IT WAS AT APPROX THIS TIME FRAME THAT WE BOTH OBSERVED THE SMA Y FLY NEXT TO THE CLOUD BANKS OFF TO OUR S. IT IS MY PROFESSIONAL OPINION THAT THERE IS NO POSSIBLE WAY FOR THAT SMA TO REMAIN IN VFR CONDITIONS REF THE DISTANCE FROM CLOUD CRITERIA IN FAR 91.155(A). AFTER ARR AT TWIN FALLS, WE ASKED GND CTL WHERE THE OTHER SMA HAD PARKED. AS WE CLBED OUT OF OUR PLANE, I ASKED THE LINE BOY IF HE KNEW WHERE THE CREW OF SUBJECT SMA WAS, AND HE POINTED TO A COUPLE WALKING ACROSS THE RAMP TOWARDS THE TERMINAL. I THEN JOGGED OVER TO THEM, AND ASKED IF THEY HAD JUST FLOWN IN FROM THE SEATTLE AREA. THEIR RESPONSE WAS 'YES.' I THEN SAID WE NEEDED TO TALK ABOUT OUR NEAR MISS AND POSSIBLE FAA VIOLATIONS. THE GENTLEMAN TOLD ME TO GO TALK TO THE FAA, AND TURNED AROUND TO CONTINUE HIS WALK TO THE TERMINAL. I RETURNED TO OUR ACFT TO GATHER MY PAPERWORK, AND WENT INTO THE FBO TO CALL THE FAA. FAR 91.113(A): THIS ACFT DID NOT APPEAR TO 'PASS OVER, UNDER, OR AHEAD OF IT UNLESS WELL CLR.' I DO NOT CONSIDER A MODE C READOUT BTWN ACFT OF 400 FT TO BE 'WELL CLR.' FAR 91.113(F): THIS ACFT CONVERGED TWICE FROM OUR L SIDE. THE FIRST TIME WAS DURING THE CONFLICT ALERT GIVEN BY ZSE DESCRIBED ABOVE, THE SECOND WAS AS WE APCHED BAKER VOR. FAR 91.155(A): AFTER OUR NEAR MISS, WE BOTH WATCHED THIS ACFT APCH THE CLOUDS WITHIN 1/2 MI LATERALLY AND 300 FT ABOVE. FAR 91.159(A): I BELIEVE IT IS THE INTENT OF THIS FAR TO FLY AT THE PROPER ALT FOR DIRECTION OF FLT WHILE OVER 3000 FT AGL. FAR 91.113(A): AT LEAST ONCE, BOTH MY PAX AND MYSELF FELT ENDANGERED BY THE FLT PATH OF SMA Y AS THE TA WAS ISSUED. I FURTHER FEEL THAT OTHER UNKNOWN ACFT COULD HAVE BEEN ENDANGERED AS THE SMA PASSED NEXT TO THE CLOUDS, ESPECIALLY WHEN IT WAS ABOVE 10000 FT. HE COULD HAVE FILED IFR, IF HE WAS INST RATED, EQUIPPED, AND QUALIFIED. VFR FLT FOLLOWING SVC, WHILE NOT REQUIRED, WOULD HAVE BEEN SAFER THAN CONTINUING ON WITHOUT TALKING TO ANYONE. A CRUISE ALT OF 11500 FT WOULD HAVE PUT SMA Y ABOVE KNOWN WX AND TFC. IT ALSO WOULD HAVE ALLOWED THE SMA TO FLY AT A PROPER ALT FOR DIRECTION OF FLT.

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.