Narrative:

I was working the northwest radar position at okc, radar approach control. I accepted a radar handoff from the northeast controller on small transport X, swbnd en route to F28. From the onset, I confused X as being a VFR aircraft and acted accordingly. When the pilot of X reported on frequency I instructed him to cross over the wiley post airport at or above 3500' from northeast to southwest. Meanwhile small aircraft Y was west of wiley post airport, northbound at 4000'. I observed X descending through 4700' in conflict with Y. Still believing that X was a VFR aircraft, I merely issued traffic to the pilot instead of climbing him to 5000' or turning him immediately to maintain a 3 mi latitude sep. When X was 1.6 mi and 300' from Y, I turned X left to 180 degrees preventing a collision. However, sep was lost and subsequently decreased to less than 1 mi. After the targets passed I informed the pilot of X that traffic was no longer a factor and instructed him to resume his own navigation to the airport. When aircraft X was approximately 7 mi northeast of F28 I informed the pilot of his position and terminated radar services. Although I take full responsibility for failing to recognize that X was an IFR aircraft, I have to wonder why the pilot of X, after receiving a VFR altitude, receiving traffic information on an aircraft that was at an altitude above the one assigned on approach, did not question me on any of these actions. ATC is a 2-WAY street and controllers are not perfect. So to any pilot, that may read this, please question any ATC instruction this is not consistent with normal practice.

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Original NASA ASRS Text

Title: LESS THAN STANDARD SEPARATION BETWEEN CORP-TWIN AND SMA. OPERATIONAL ERROR.

Narrative: I WAS WORKING THE NW RADAR POS AT OKC, RADAR APCH CTL. I ACCEPTED A RADAR HDOF FROM THE NE CTLR ON SMT X, SWBND ENRTE TO F28. FROM THE ONSET, I CONFUSED X AS BEING A VFR ACFT AND ACTED ACCORDINGLY. WHEN THE PLT OF X RPTED ON FREQ I INSTRUCTED HIM TO CROSS OVER THE WILEY POST ARPT AT OR ABOVE 3500' FROM NE TO SW. MEANWHILE SMA Y WAS W OF WILEY POST ARPT, NBOUND AT 4000'. I OBSERVED X DSNDING THROUGH 4700' IN CONFLICT WITH Y. STILL BELIEVING THAT X WAS A VFR ACFT, I MERELY ISSUED TFC TO THE PLT INSTEAD OF CLBING HIM TO 5000' OR TURNING HIM IMMEDIATELY TO MAINTAIN A 3 MI LAT SEP. WHEN X WAS 1.6 MI AND 300' FROM Y, I TURNED X LEFT TO 180 DEGS PREVENTING A COLLISION. HOWEVER, SEP WAS LOST AND SUBSEQUENTLY DECREASED TO LESS THAN 1 MI. AFTER THE TARGETS PASSED I INFORMED THE PLT OF X THAT TFC WAS NO LONGER A FACTOR AND INSTRUCTED HIM TO RESUME HIS OWN NAV TO THE ARPT. WHEN ACFT X WAS APPROX 7 MI NE OF F28 I INFORMED THE PLT OF HIS POS AND TERMINATED RADAR SVCS. ALTHOUGH I TAKE FULL RESPONSIBILITY FOR FAILING TO RECOGNIZE THAT X WAS AN IFR ACFT, I HAVE TO WONDER WHY THE PLT OF X, AFTER RECEIVING A VFR ALT, RECEIVING TFC INFO ON AN ACFT THAT WAS AT AN ALT ABOVE THE ONE ASSIGNED ON APCH, DID NOT QUESTION ME ON ANY OF THESE ACTIONS. ATC IS A 2-WAY STREET AND CTLRS ARE NOT PERFECT. SO TO ANY PLT, THAT MAY READ THIS, PLEASE QUESTION ANY ATC INSTRUCTION THIS IS NOT CONSISTENT WITH NORMAL PRACTICE.

Data retrieved from NASA's ASRS site as of August 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.