Date: 202012
Local time of day: 1201-1800
Location: F70.Airport, CA
Flight conditions: VMC
Light: Daylight
Aircraft: Small Aircraft
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Personal
Flight phase: Initial Approach
Airspace: Class G F70
ATC / advisory: UNICOM F70
Second aircraft: Any Unknown or Unlisted Aircraft Manufacturer
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Commercial
Human factors: Communication Breakdown; Situational Awareness
Anomaly: Conflict NMAC
Result: Flight Crew Took Evasive Action
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: I was approaching F70 from the southeast after a personal flight while making radio calls every few miles as I noticed on my ADS-B in several targets circling around the airport due to intense student activity.Someone made a radio call a few minutes before I was in the vicinity of another aircraft cutting them off on downwind too and I prepared myself for heavy traffic in the pattern and trying to find an opening so I could join the downwind.Upon entering the 45 for downwind I noticed visually an aircraft on the upwind taking off and repeatedly asked his intentions and if he could see me.There was no answer and seeing him proceed on runway heading I continued on the 45 for downwind being confident he wouldn't start a turn to crosswind until he reached close to pattern altitude as is recommended for the noise abatement procedure out of F70 for departures from Runway 18.Then I saw him maneuver for the crosswind maybe 500 feet below my altitude which was at pattern and make a radio call in that regards. At this point I had contacted him several times regarding his intentions and whether he could see me but without any answer.Seeing him turn and put me on the direct collision course with me although 300 ft. below me I decided to execute a 360 degree turn saw him coming extremely near me. Finally he acknowledged my presence in a subsequent radio call.I continued the full turn and reentered downwind.F70 was extremely busy that day with several schools on the field and at one point I saw no less than 5 aircraft in the traffic pattern. Needless to say a Tower is badly needed in that field for the safety of flight as the indiscriminate addition of several aircraft from several schools without any sort of coordination between those schools makes this urgently needed.A bit of courtesy goes a long way too and someone was nice enough to extend their downwind for me earlier in the day so I could depart as I had to hold short of the active runway at least 10 minutes as one aircraft after another was landing with no end in sight.On my side I should have waited outside the pattern on a hold in a safe area until there was no aircraft on upwind and the downwind leg would be fully opened; with adequate radio communications ensuring everyone in the pattern has knowledge of any other traffic with acknowledgement for all.This was my first experience with this field with that many aircraft in the pattern and the lesson learned here is to stay outside an uncontrolled field until there is fewer than a set limit of aircraft that one can set as personal limit.Such a personal limit is not taught at all as part of any training curriculum nor in the AIM in my knowledge.Most uncontrolled field are uncontrolled because of very low traffic but some reach levels just below the threshold needed for a tower and F70 seems to be in that category.Also the schools on the field could coordinate some kind of schedule among themselves so not everyone is up in the air at the same time. Poisson's law dictates things happen in bursts unless there is coordination to avert it.




Synopsis: GA pilot reported an NMAC in the pattern at F70 airport.