Narrative:

Some low stratus and ground fog was beginning to form in the area, but it wasn't a direct factor in the incident. The tower was closed, so I called on the CTAF 8 mi out that I was inbound for straight in to runway 17. On approximately 4 mi final another aircraft called over the OM inbound on low approach. I could see another aircraft (or so I thought) approximately 3/4 mi ahead of me on a somewhat erratic approach, but I couldn't see the aircraft I assumed was behind me that had called the OM. I kept up cruise speed to put distance between me and the aircraft doing the ILS. I did a couple of s-turns to make myself more visible and to try to spot the phantom aircraft behind me. I then realized what was happening. I had fixed on the thought that I could be run down from behind, when all the time the aircraft I was looking for was the one in front of me. This realization took the form of an aircraft silhouette approximately 50' above and 100' ahead of me. I had almost caught up with him. I did a 360 degree turn to the left, and when I rolled out on final again, the other aircraft was just beginning his missed approach, completing unaware of how close he came to becoming a biplane. Contributing factors to this were fatigue on my part, a concern for the growing areas of stratus and ground fog that were forming, and a failure on my part to use a standard pattern entry instead of doing a straight-in. A thought, for future reference, would be that when doing IFR practice approachs, the pilot or instrument should call actual position when on CTAF, rather than where they were 30 seconds or 1 min ago.

Related reports:

Google
 

Original NASA ASRS Text

Title: CLOSE PROX 2 GA SMA'S IN TRAFFIC TO TIW.

Narrative: SOME LOW STRATUS AND GND FOG WAS BEGINNING TO FORM IN THE AREA, BUT IT WASN'T A DIRECT FACTOR IN THE INCIDENT. THE TWR WAS CLOSED, SO I CALLED ON THE CTAF 8 MI OUT THAT I WAS INBND FOR STRAIGHT IN TO RWY 17. ON APPROX 4 MI FINAL ANOTHER ACFT CALLED OVER THE OM INBND ON LOW APCH. I COULD SEE ANOTHER ACFT (OR SO I THOUGHT) APPROX 3/4 MI AHEAD OF ME ON A SOMEWHAT ERRATIC APCH, BUT I COULDN'T SEE THE ACFT I ASSUMED WAS BEHIND ME THAT HAD CALLED THE OM. I KEPT UP CRUISE SPD TO PUT DISTANCE BTWN ME AND THE ACFT DOING THE ILS. I DID A COUPLE OF S-TURNS TO MAKE MYSELF MORE VISIBLE AND TO TRY TO SPOT THE PHANTOM ACFT BEHIND ME. I THEN REALIZED WHAT WAS HAPPENING. I HAD FIXED ON THE THOUGHT THAT I COULD BE RUN DOWN FROM BEHIND, WHEN ALL THE TIME THE ACFT I WAS LOOKING FOR WAS THE ONE IN FRONT OF ME. THIS REALIZATION TOOK THE FORM OF AN ACFT SILHOUETTE APPROX 50' ABOVE AND 100' AHEAD OF ME. I HAD ALMOST CAUGHT UP WITH HIM. I DID A 360 DEG TURN TO THE LEFT, AND WHEN I ROLLED OUT ON FINAL AGAIN, THE OTHER ACFT WAS JUST BEGINNING HIS MISSED APCH, COMPLETING UNAWARE OF HOW CLOSE HE CAME TO BECOMING A BIPLANE. CONTRIBUTING FACTORS TO THIS WERE FATIGUE ON MY PART, A CONCERN FOR THE GROWING AREAS OF STRATUS AND GND FOG THAT WERE FORMING, AND A FAILURE ON MY PART TO USE A STANDARD PATTERN ENTRY INSTEAD OF DOING A STRAIGHT-IN. A THOUGHT, FOR FUTURE REF, WOULD BE THAT WHEN DOING IFR PRACTICE APCHS, THE PLT OR INSTR SHOULD CALL ACTUAL POS WHEN ON CTAF, RATHER THAN WHERE THEY WERE 30 SECS OR 1 MIN AGO.

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.