Narrative:

I was inbound to the cgz airport; about 3 nm northeast. I reported my position on the CTAF and that I was planning a left downwind entry to the active runway; which was runway 05. There was a fair number of trainer aircraft in the vicinity of the tfd VOR executing practice instrument approaches. A light twin announced that he was upwind of runway 5; then crosswind. Since I knew that his departure could result in a possible conflict; I maintained extra caution and vigilance. Even so; I did not see the northbound aircraft until it was above the horizon; about 1/8 mile away. There wasn't enough time for evasive action; the aircraft passed behind me. This kind of incident may be a precursor to possible in-flight collisions at this airport because of very heavy training activity with many non-standard operations. Exacerbating the situation was the fact that numerous training aircraft over the tfd VOR (8 miles southwest) were communication with each other with information on altitudes; distances from the fix; type of approaches they were doing; all on the CTAF for cgz. All of this continuous radio chatter precluded my opportunity to announce my position as I entered downwind and may have been a factor as to why the other aircraft failed to see my aircraft.

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Original NASA ASRS Text

Title: Pilot reported that high traffic volume and frequency congestion at a non-towered airport resulted in a NMAC.

Narrative: I was inbound to the CGZ airport; about 3 nm northeast. I reported my position on the CTAF and that I was planning a left downwind entry to the active runway; which was Runway 05. There was a fair number of trainer aircraft in the vicinity of the TFD VOR executing practice instrument approaches. A light twin announced that he was upwind of runway 5; then crosswind. Since I knew that his departure could result in a possible conflict; I maintained extra caution and vigilance. Even so; I did not see the northbound aircraft until it was above the horizon; about 1/8 mile away. There wasn't enough time for evasive action; the aircraft passed behind me. This kind of incident may be a precursor to possible in-flight collisions at this airport because of very heavy training activity with many non-standard operations. Exacerbating the situation was the fact that numerous training aircraft over the TFD VOR (8 miles southwest) were communication with each other with information on altitudes; distances from the fix; type of approaches they were doing; all on the CTAF for CGZ. All of this continuous radio chatter precluded my opportunity to announce my position as I entered downwind and may have been a factor as to why the other aircraft failed to see 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.