Date: 202009
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: Haze / Smoke; 10
Light: Dusk
Aircraft: Small Aircraft; Low Wing; 1 Eng; Fixed Gear
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Personal
Flight phase: Final Approach
Airspace: Class E ZZZ
ATC / advisory: CTAF ZZZ
Second aircraft: Small Aircraft; High Wing; 1 Eng; Fixed Gear
Reporter organization: Personal
Reporter function: Pilot Flying; Single Pilot
Reporter qualification: Flight Crew Private
Human factors: Confusion; Communication Breakdown; Distraction; Troubleshooting; Situational Awareness
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action
Contributing factors: Procedure; Human Factors; Environment - Non Weather Related; Staffing
Primary problem: Staffing

Narrative: ZZZ Class D Airspace has been operating on reduced hours since COVID-19 started. The airspace in the traffic pattern reverts to Class E once the Tower is closed and pilots make announcements on the CTAF.The traffic pattern was very busy at dusk as I was arriving back from ZZZ1. I was entering the pattern by flying over the field at 2;200 and then executing a teardrop entry into a 45 for left traffic Runway XX. There was Aircraft Y on Left Downwind for Runway XX as Aircraft Z approached directly from the east (in opposite traffic); at pattern altitude in what it described as a 'wide entry' to join the 45 for left downwind. This entry was not wide as Aircraft Y reported that Aircraft Z had almost collided with it in the traffic pattern and reprimanded the pilot for his choice of pattern entry procedure. I was forced to abort my tear drop entry as Aircraft Z proceeded directly for my location. I executed a 360 degree holding turn and observed Aircraft Z pass approximately 800 feet below me. I sequenced in behind Aircraft Z and maintained visual contact. I extended my left downwind slightly for spacing when I observed Aircraft A transiting the airspace; NORDO; at 2;300 feet - this was the altitude I was previously at and the altitude which I had crossed midfield. While this aircraft didn't have to make any announcements; it is reckless to transit a busy airport; slightly above its traffic pattern; while NORDO. Immediately afterwards; while I was turning left base for Runway XX; an aircraft announced that it was entering 'Right traffic' for Runway XX. While we are used to flying right traffic when the Tower is open; this is not the prescribed procedure while on CTAF and can create a very dangerous situation. Aircraft B on the RNAV XX approach was forced to go missed given the situation in the traffic pattern.This temporary reduction in Class D services has created hazards for pilots flying in this busy airspace; as traffic has picked up again to levels that warrant full-time Class D service hours. This entire situation could have been avoided had ZZZ's Control Tower been in normal; pre-COVID; operational hours.




Synopsis: GA pilot reported reduced Tower services at a Class D airport due to COVID-19 has resulted in an unsafe environment and described several conflicts occurring while the Tower was closed.