Narrative:

I was PIC on an IFR flight plan to dts. I was talking to eglin approach and he cleared me for the visual approach to runway 14 at dts. He said he had an AC90 on final and a king air about to depart off dts on runway 14. I was making radio calls on what I found out to be an invalid frequency. I was over the top of runway 14 at the center of the airport and I looked out my left window and saw the AC90 make a hard left turn to avoid hitting me. I called eglin approach and told him about it and told him what frequency I was on. He told me that was the wrong frequency. He gave me the new frequency and by that time I was now behind the AC90 and landed without incident. Callback conversation with reporter revealed the following information: reporter stated that a NOTAM existed for CTAF frequency; but it was not brought to his attention during briefing. This resulted in communicating on the wrong frequency. Additionally; the conflicting aircraft had entered an overhead pattern; so it was directly over the runway at traffic pattern altitude.

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Original NASA ASRS Text

Title: C-500 WAS INVOLVED IN NMAC. FLT WAS CLEARED FOR VISUAL APCH AND WAS COMMUNICATING ON WRONG FREQ WHEN EVENT OCCURRED.

Narrative: I WAS PIC ON AN IFR FLT PLAN TO DTS. I WAS TALKING TO EGLIN APCH AND HE CLRED ME FOR THE VISUAL APCH TO RWY 14 AT DTS. HE SAID HE HAD AN AC90 ON FINAL AND A KING AIR ABOUT TO DEPART OFF DTS ON RWY 14. I WAS MAKING RADIO CALLS ON WHAT I FOUND OUT TO BE AN INVALID FREQ. I WAS OVER THE TOP OF RWY 14 AT THE CTR OF THE ARPT AND I LOOKED OUT MY L WINDOW AND SAW THE AC90 MAKE A HARD L TURN TO AVOID HITTING ME. I CALLED EGLIN APCH AND TOLD HIM ABOUT IT AND TOLD HIM WHAT FREQ I WAS ON. HE TOLD ME THAT WAS THE WRONG FREQ. HE GAVE ME THE NEW FREQ AND BY THAT TIME I WAS NOW BEHIND THE AC90 AND LANDED WITHOUT INCIDENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THAT A NOTAM EXISTED FOR CTAF FREQ; BUT IT WAS NOT BROUGHT TO HIS ATTENTION DURING BRIEFING. THIS RESULTED IN COMMUNICATING ON THE WRONG FREQ. ADDITIONALLY; THE CONFLICTING ACFT HAD ENTERED AN OVERHEAD PATTERN; SO IT WAS DIRECTLY OVER THE RWY AT TFC PATTERN ALT.

Data retrieved from NASA's ASRS site as of January 2009 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.