Narrative:

Departed cos airport at about XA20, with a VFR issued clearance. The trip was cos to a ranch destination in northeast new mexico, about 160 mi south on about a 165 degree heading. Cos departure control asked if I wanted flight following when about 15 mi south of cos climbing to 15500 ft. I responded affirmative. After a handoff attempt, the departure controller advised me that ZDV was busy and wouldn't take us for advisories and to squawk VFR and terminated radar services. Approximately 3-4 mins later while leveling at 15500 ft I saw a DC9 converging from my right at about 45-60 degrees. I estimated the aircraft to be about 1-2 mi at that time. After a couple of seconds (?) to orient his flight path and altitude, I realized there was a serious conflict. He was slightly above and in a descending left turn. I made a steep right turn and was able to avoid and remain in visual contact while the DC9 passed off my left side at about 100-200 yds. I then instantly flew through his wake. I had no knowledge if the pilot of the DC9 saw my aircraft until I called cos airport operations where I deduced they were heading. He indicated he had seen me for about 3 or 4 seconds only after my aircraft gave a better visual profile. He said he had been told by ZDV of the conflict earlier and that center suggested he expedite from FL190 to 14000 ft. This incident seems like a case of IFR, VFR mixing and not using the same communication frequency. Had ZDV taken our flight following request, both aircraft would have been told of the coming conflict much earlier. Fortunately, the see and avoid system did work.

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Original NASA ASRS Text

Title: NMAC BTWN A TWIN TURBOPROP CLBING OUT AND A DSNDING DC9. THE RPTR TOOK EVASIVE ACTION BY MAKING A STEEP R TURN.

Narrative: DEPARTED COS ARPT AT ABOUT XA20, WITH A VFR ISSUED CLRNC. THE TRIP WAS COS TO A RANCH DEST IN NE NEW MEXICO, ABOUT 160 MI S ON ABOUT A 165 DEG HDG. COS DEP CTL ASKED IF I WANTED FLT FOLLOWING WHEN ABOUT 15 MI S OF COS CLBING TO 15500 FT. I RESPONDED AFFIRMATIVE. AFTER A HDOF ATTEMPT, THE DEP CTLR ADVISED ME THAT ZDV WAS BUSY AND WOULDN'T TAKE US FOR ADVISORIES AND TO SQUAWK VFR AND TERMINATED RADAR SVCS. APPROX 3-4 MINS LATER WHILE LEVELING AT 15500 FT I SAW A DC9 CONVERGING FROM MY R AT ABOUT 45-60 DEGS. I ESTIMATED THE ACFT TO BE ABOUT 1-2 MI AT THAT TIME. AFTER A COUPLE OF SECONDS (?) TO ORIENT HIS FLT PATH AND ALT, I REALIZED THERE WAS A SERIOUS CONFLICT. HE WAS SLIGHTLY ABOVE AND IN A DSNDING L TURN. I MADE A STEEP R TURN AND WAS ABLE TO AVOID AND REMAIN IN VISUAL CONTACT WHILE THE DC9 PASSED OFF MY L SIDE AT ABOUT 100-200 YDS. I THEN INSTANTLY FLEW THROUGH HIS WAKE. I HAD NO KNOWLEDGE IF THE PLT OF THE DC9 SAW MY ACFT UNTIL I CALLED COS ARPT OPS WHERE I DEDUCED THEY WERE HEADING. HE INDICATED HE HAD SEEN ME FOR ABOUT 3 OR 4 SECONDS ONLY AFTER MY ACFT GAVE A BETTER VISUAL PROFILE. HE SAID HE HAD BEEN TOLD BY ZDV OF THE CONFLICT EARLIER AND THAT CTR SUGGESTED HE EXPEDITE FROM FL190 TO 14000 FT. THIS INCIDENT SEEMS LIKE A CASE OF IFR, VFR MIXING AND NOT USING THE SAME COM FREQ. HAD ZDV TAKEN OUR FLT FOLLOWING REQUEST, BOTH ACFT WOULD HAVE BEEN TOLD OF THE COMING CONFLICT MUCH EARLIER. FORTUNATELY, THE SEE AND AVOID SYS DID WORK.

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.