Narrative:

Somewhere near huo VOR flight was cleared to descend out of 6000' to maintain 4000'. In our descent around 5200' the PNF (captain) noticed a single engine small aircraft on a collision course approaching from the right. The sing engine aircraft appeared to be in level flight at approximately 5500' heading esebound. No traffic advisory was given to us by ATC. When ATC was advised of the situation they said that they were not showing any aircraft in our area. It appears that the single engine aircraft was flying at the correct altitude for his direction of flight. My guess is that he never saw us due to the hazy sky conditions and the fact that he probably was heading into the sun at that time of morning. Although evasive action was not required in this instance, a different descent rate than what we were doing would have required immediate action by the PNF. The small aircraft passed directly over top from right to left, with 200-300' sep horizontal and vertical when first noticed and continued over top our aircraft with 200-300' sep vertical and 0 horizontal. The small aircraft appeared to be off the arwy and in uncontrolled airspace at the correct altitude for his direction of flight. Perhaps this is what we can expect in the future as smaller single engine aircraft with their xponders inoperative or off skirt the edges of the new bigger and better TCA's in the country. If the FAA is going to extend the TCA boundaries and force aircraft to skirt its edges, then they should either require all aircraft to be transponder equipped or they should get some new radar that can pick up secondary targets that are not transponder equipped.

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Original NASA ASRS Text

Title: DESCENDING ACR CREW SPOTS SMA ON COLLISION COURSE. NO TRAFFIC CALL. CONTINUED DESCENT BUT NMAC.

Narrative: SOMEWHERE NEAR HUO VOR FLT WAS CLRED TO DSND OUT OF 6000' TO MAINTAIN 4000'. IN OUR DSCNT AROUND 5200' THE PNF (CAPT) NOTICED A SINGLE ENG SMA ON A COLLISION COURSE APCHING FROM THE RIGHT. THE SING ENG ACFT APPEARED TO BE IN LEVEL FLT AT APPROX 5500' HDG ESEBOUND. NO TFC ADVISORY WAS GIVEN TO US BY ATC. WHEN ATC WAS ADVISED OF THE SITUATION THEY SAID THAT THEY WERE NOT SHOWING ANY ACFT IN OUR AREA. IT APPEARS THAT THE SINGLE ENG ACFT WAS FLYING AT THE CORRECT ALT FOR HIS DIRECTION OF FLT. MY GUESS IS THAT HE NEVER SAW US DUE TO THE HAZY SKY CONDITIONS AND THE FACT THAT HE PROBABLY WAS HDG INTO THE SUN AT THAT TIME OF MORNING. ALTHOUGH EVASIVE ACTION WAS NOT REQUIRED IN THIS INSTANCE, A DIFFERENT DSCNT RATE THAN WHAT WE WERE DOING WOULD HAVE REQUIRED IMMEDIATE ACTION BY THE PNF. THE SMA PASSED DIRECTLY OVER TOP FROM RIGHT TO LEFT, WITH 200-300' SEP HORIZ AND VERT WHEN FIRST NOTICED AND CONTINUED OVER TOP OUR ACFT WITH 200-300' SEP VERT AND 0 HORIZ. THE SMA APPEARED TO BE OFF THE ARWY AND IN UNCONTROLLED AIRSPACE AT THE CORRECT ALT FOR HIS DIRECTION OF FLT. PERHAPS THIS IS WHAT WE CAN EXPECT IN THE FUTURE AS SMALLER SINGLE ENG ACFT WITH THEIR XPONDERS INOP OR OFF SKIRT THE EDGES OF THE NEW BIGGER AND BETTER TCA'S IN THE COUNTRY. IF THE FAA IS GOING TO EXTEND THE TCA BOUNDARIES AND FORCE ACFT TO SKIRT ITS EDGES, THEN THEY SHOULD EITHER REQUIRE ALL ACFT TO BE XPONDER EQUIPPED OR THEY SHOULD GET SOME NEW RADAR THAT CAN PICK UP SECONDARY TARGETS THAT ARE NOT XPONDER EQUIPPED.

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.