Date: 202006
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: Calm Winds; 50
Light: Daylight
Aircraft: Small Aircraft; High Wing; 1 Eng; Fixed Gear
Operating under: Part 91
Flight plan: None
Mission: Training
Flight phase: Landing
Airspace: Class E ZZZ
ATC / advisory: UNICOM ZZZ
Second aircraft: Small Aircraft; Low Wing; 1 Eng; Fixed Gear
Reporter organization: Other unknown
Reporter function: Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Commercial
Human factors: Confusion; Distraction; Situational Awareness; Communication Breakdown; Training / Qualification
Anomaly: Conflict NMAC
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: While on short-short final for RWY XX.  Aircraft Y turn a tight diving base to final -- over took us; flew over-top of us; and proceeded to landed in front of us. The Aircraft Y's left main landing gear cleared our aircraft by only 3 FEET! Aircraft Y entered ZZZ's airspace. Making a radio call on (incorrect frequency) NOT CTAF. HE WAS ON OUR COMPANY FREQUENCY. 15 miles North.  Announcing he was setting up for a Left-Downwind for RWY Y.  ZZZ calm wind RWY is RWY XX as published. Several attempts were made to contact Aircraft Y and inform them of their error and the business of the airspace.  Aircraft Y never switch to CTAF until it was too late.  He proceeded to enter a 4 mile Left-Downwind for RWY Y.  (Wrong frequency) was quiet with little active. However the CTAF was not.  Aircraft Z and I were currently joining the Right-Downwind for RWY XX.  Aircraft Z went wide and we were staying tight-in on the Right-Downwind for RWY XX. We were in contact with each other and had a couple of miles lateral separation; as we normally do. The Aircraft Y not seeing either of us in the Right-Downwind for RWY XX; split us going the opposite direction; at traffic pattern altitude for RWY Y.  Aircraft Z was unaware and not monitoring (wrong frequency).  So; I issued Aircraft Z a traffic alert.  I then issued another traffic alert as both the Aircraft Y and Aircraft Z; aircraft turned their base respectively for opposite ends of the RWY. The Aircraft Y finally answered our attempts to have them switch to CTAF; as they were in the base turn to the RWY Y. The Aircraft Y executed a course reversal and jointed the correct downwind for RWY XX.  The Aircraft Y still unaware of all the traffic inbound for RWY XX.  Aircraft Y made a short and tight re-entry to the correct downwind for RWY XX; then turned a non-standard tight diving base to final approach - overflying us; and cutting off other RNAV traffic in bound traffic. We had three in sequence for RWY XX.  I was made aware of the overtaking Aircraft Y; because I luckily saw a brisk aircraft shadow overtaking us from behind.  I performed an evasive maneuver to avoid a mid-air. I reduced airspeed to the slowest KIAS speed possible; as the shadow approached.  I matched the descent rate of the Mooney; using our above skylight window. We descended as low as I could; estimated 30 feet off the deck. now using our dangerously slow-slow speed to create separation from the diving plan. Once we were clear of the Aircraft Y's tail we executed a climbing right-hand go-around.  I was worried about striking our wings against Aircraft Y -- we were literally that close!Aircraft Y proceeded to land on RWY XX; touching down at the [XY] intersection.  Aircraft Z was still on his roll out and planning to clear at the [XY+1] intersection. I issued a third traffic alert to Aircraft Z. Aircraft Z expedited his exit.  Aircraft Z cleared in time. The Aircraft Y stopped aggressively.   I had a birds-eye view as we were conducting a go-round off-set up wind climb.




Synopsis: Pilot reported a NMAC with an aircraft on very short final.