Narrative:

I departed ZZZ direct to aio to attend a fly-in with one passenger. I communicated 10 miles northeast of aio that I would enter the left downwind for runway 02. Aircraft Y pilot reported 6 south of aio for a straight in approach to runway 02. A couple minutes later I communicated to the aircraft Y pilot that I was entering the downwind to runway 02 and would land after. At this time aircraft Z reported 5 miles northwest and would enter the downwind to runway 02. Aircraft west reported 8 to the west of aio and would overfly the field before entering the downwind to runway 02. I again reported on the left downwind to runway 02. Not more than 20 seconds later my passenger pointed out aircraft Z; which passed slightly behind us from the right and slightly below us. I took evasive action to avoid the aircraft and exited the pattern to the west.I reentered the pattern behind aircraft west. Aircraft west pilot extended his downwind and eventually turned onto the upwind without landing. I suspect he thought I would overtake him and land despite me communicating that I would follow aircraft west and land after him. Unsure what aircraft west pilot would do; despite communicating on CTAF; I continued to follow aircraft west through the entire pattern. The aircraft west pilot eventually turned onto a 2 mile final on his second circuit and landed. The pilot exited 4500 down the 5000 runway. Shortly after aircraft west pilot exited the runway I was able to land without incident. There was a lot of traffic at the airport due to the fly-in. I arrived at a particularly busy time. Despite communicating on the radio multiple times; a mid-air collision almost occurred. Based on the report of aircraft Z being 5 miles out as I entered the pattern; I had thought that it was no factor. Aircraft Z was not in the position that it had reported on CTAF. If I don't avoid fly-in's entirely in the future. I will ensure that I communicate more directly with each pilot that could create a conflict. I made the mistake of trusting where the pilot said. His aircraft was also positioned in a location that was not visible from the pilot's seat of [my aircraft].

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Original NASA ASRS Text

Title: GA pilot reported several airborne conflicts and a near-mid-air-collision while entering the pattern at AIO CTAF airport.

Narrative: I departed ZZZ direct to AIO to attend a fly-in with one passenger. I communicated 10 miles northeast of AIO that I would enter the left downwind for runway 02. Aircraft Y pilot reported 6 south of AIO for a straight in approach to runway 02. A couple minutes later I communicated to the Aircraft Y pilot that I was entering the downwind to runway 02 and would land after. At this time Aircraft Z reported 5 miles northwest and would enter the downwind to runway 02. Aircraft W reported 8 to the west of AIO and would overfly the field before entering the downwind to runway 02. I again reported on the left downwind to runway 02. Not more than 20 seconds later my passenger pointed out Aircraft Z; which passed slightly behind us from the right and slightly below us. I took evasive action to avoid the aircraft and exited the pattern to the west.I reentered the pattern behind Aircraft W. Aircraft W pilot extended his downwind and eventually turned onto the upwind without landing. I suspect he thought I would overtake him and land despite me communicating that I would follow Aircraft W and land after him. Unsure what Aircraft W pilot would do; despite communicating on CTAF; I continued to follow Aircraft W through the entire pattern. The Aircraft W pilot eventually turned onto a 2 mile final on his second circuit and landed. The pilot exited 4500 down the 5000 runway. Shortly after Aircraft W pilot exited the runway I was able to land without incident. There was a lot of traffic at the airport due to the fly-in. I arrived at a particularly busy time. Despite communicating on the radio multiple times; a mid-air collision almost occurred. Based on the report of Aircraft Z being 5 miles out as I entered the pattern; I had thought that it was no factor. Aircraft Z was not in the position that it had reported on CTAF. If I don't avoid fly-in's entirely in the future. I will ensure that I communicate more directly with each pilot that could create a conflict. I made the mistake of trusting where the pilot said. His aircraft was also positioned in a location that was not visible from the pilot's seat of [my aircraft].

Data retrieved from NASA's ASRS site 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.