Narrative:

While I was in a downwind phase of landing (midfield) pattern, another aircraft almost descended on top of my aircraft. It was your typical high wing, low wing conflict. I was in high wing aircraft on a downwind leg of traffic pattern when a low wing entered the traffic pattern using a midfield crosswind entry and almost descended on top of my high wing. Both the low wing pilot and I did not know it was happening. Another aircraft who was following me in the traffic pattern saw the low wing almost descend on top of me. I had been radioing my position reports and the other pilot had probably not heard them for whatever reason, or mistook the other aircraft that was following me as me and did not see any conflict. When I got on the ground, I spoke to the pilot of the low wing and the pilot who was following me to determine what went wrong. Evidently, the low wing pilot crossed over the airport at 500' above pattern altitude and then descended down to pattern altitude in the downwind leg. He did not use the standard 45 degree FAA aim method. Again the resolution is to have pilots only use 1 type of pattern entry at uncontrolled fields and radio position at all times. Also, and very importantly, the unicom frequency at I77 is 123.0. There are several other airports in the area on the same unicom frequency (middletown, oh; blue ash, oh; etc). We need less crowded unicom frequencys in higher traffic areas.

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Original NASA ASRS Text

Title: IN TRAFFIC PATTERN AT UNCONTROLLED ARPT LOW WING ACFT DESCENDED ON TOP HIGH WING ACFT MISSING BY 30'.

Narrative: WHILE I WAS IN A DOWNWIND PHASE OF LNDG (MIDFIELD) PATTERN, ANOTHER ACFT ALMOST DSNDED ON TOP OF MY ACFT. IT WAS YOUR TYPICAL HIGH WING, LOW WING CONFLICT. I WAS IN HIGH WING ACFT ON A DOWNWIND LEG OF TFC PATTERN WHEN A LOW WING ENTERED THE TFC PATTERN USING A MIDFIELD XWIND ENTRY AND ALMOST DSNDED ON TOP OF MY HIGH WING. BOTH THE LOW WING PLT AND I DID NOT KNOW IT WAS HAPPENING. ANOTHER ACFT WHO WAS FOLLOWING ME IN THE TFC PATTERN SAW THE LOW WING ALMOST DSND ON TOP OF ME. I HAD BEEN RADIOING MY POS RPTS AND THE OTHER PLT HAD PROBABLY NOT HEARD THEM FOR WHATEVER REASON, OR MISTOOK THE OTHER ACFT THAT WAS FOLLOWING ME AS ME AND DID NOT SEE ANY CONFLICT. WHEN I GOT ON THE GND, I SPOKE TO THE PLT OF THE LOW WING AND THE PLT WHO WAS FOLLOWING ME TO DETERMINE WHAT WENT WRONG. EVIDENTLY, THE LOW WING PLT CROSSED OVER THE ARPT AT 500' ABOVE PATTERN ALT AND THEN DSNDED DOWN TO PATTERN ALT IN THE DOWNWIND LEG. HE DID NOT USE THE STANDARD 45 DEG FAA AIM METHOD. AGAIN THE RESOLUTION IS TO HAVE PLTS ONLY USE 1 TYPE OF PATTERN ENTRY AT UNCONTROLLED FIELDS AND RADIO POS AT ALL TIMES. ALSO, AND VERY IMPORTANTLY, THE UNICOM FREQ AT I77 IS 123.0. THERE ARE SEVERAL OTHER ARPTS IN THE AREA ON THE SAME UNICOM FREQ (MIDDLETOWN, OH; BLUE ASH, OH; ETC). WE NEED LESS CROWDED UNICOM FREQS IN HIGHER TFC AREAS.

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.