Narrative:

After an uneventful landing on runway 18 at ZZZZ following a local sight-seeing flight with my nephew; I taxied back for another takeoff and trip around the pattern for one more landing. During the taxi back another aircraft was observed in the area; but was using a right hand traffic pattern rather than the normal left hand traffic pattern. The aircraft was also not transmitting on the CTAF of 122.9. The other aircraft was observed to make a low approach to runway 18 and continue south. I announced our takeoff intention on the CTAF 122.9; kept the other aircraft in sight and entered the active runway for takeoff. During the upwind and left downwind portion; the other aircraft was observed to make a very wide right traffic pattern and appeared to be climbing as if to leave the airport area to the north. I continued on our left downwind; then made a left base at the appropriate time. The other aircraft was observed to be turning slightly in our direction; but was above us and appeared to be leaving the pattern as it was well to our west in a northerly direction. Still no radio calls being made from the other aircraft. I announced every position in the pattern and announced on final to runway 18 as well. On short final; at approximately 150 feet; the other aircraft overtook us and overflew us by approximately 30 feet. I took immediate evasive action by descending slightly and turning immediately to the right (away from obstructions on the ground). I then continued with a full missed approached and climbed out parallel to the other aircraft's track. The other aircraft was observed to commence another low approach. I attempted to contact the other pilot on the local CTAF and another unicom frequency from a nearby airport; but received no response. The other aircraft; again made a very wide right traffic pattern. I continued with the left traffic pattern as we were well behind the faster aircraft by that time. I made an abbreviated pattern and attempted to contact the other aircraft several times; with no luck. I made a normal landing; well before the other aircraft and observed it perform another low approach from a right hand traffic pattern. It was still conducting low approaches as I taxied back to the hangar.the problem arose due to the other aircraft flying an improper and non-standard traffic pattern; as well as not communicating with other aircraft in the traffic pattern. I later learned from the FBO that owns that airplane that it was on a training flight; so the flight instructor was likely distracted by the student's performance and did not observe my airplane in the traffic pattern. After the last observed low approach; the other aircraft looked like it began using a left hand traffic pattern for the next couple of low approaches; so it makes me think they finally saw us and realized that they were using an incorrect pattern. The only other factor is that they were likely on the wrong radio frequency. A factor enhancing safety was that because my aircraft and the other aircraft are adsb compliant; I was able to track him well with onboard equipment. This enhanced safety and situational awareness; especially after the incident.I have since contacted the FBO that owns the aircraft and reported the incident to their chief flight instructor. I informed them of the correct CTAF and pattern so that the information can be passed along to their flight instructors for future use and to enhance the safety of operations at ZZZZ.

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Original NASA ASRS Text

Title: Pilot reported an NMAC event during landing with a non reporting aircraft in traffic pattern.

Narrative: After an uneventful landing on runway 18 at ZZZZ following a local sight-seeing flight with my nephew; I taxied back for another takeoff and trip around the pattern for one more landing. During the taxi back another aircraft was observed in the area; but was using a right hand traffic pattern rather than the normal left hand traffic pattern. The aircraft was also not transmitting on the CTAF of 122.9. The other aircraft was observed to make a low approach to RWY 18 and continue south. I announced our takeoff intention on the CTAF 122.9; kept the other aircraft in sight and entered the active runway for takeoff. During the upwind and left downwind portion; the other aircraft was observed to make a very wide right traffic pattern and appeared to be climbing as if to leave the airport area to the north. I continued on our left downwind; then made a left base at the appropriate time. The other aircraft was observed to be turning slightly in our direction; but was above us and appeared to be leaving the pattern as it was well to our west in a northerly direction. Still no radio calls being made from the other aircraft. I announced every position in the pattern and announced on final to runway 18 as well. On short final; at approximately 150 feet; the other aircraft overtook us and overflew us by approximately 30 feet. I took immediate evasive action by descending slightly and turning immediately to the right (away from obstructions on the ground). I then continued with a full missed approached and climbed out parallel to the other aircraft's track. The other aircraft was observed to commence another low approach. I attempted to contact the other pilot on the local CTAF and another UNICOM frequency from a nearby airport; but received no response. The other aircraft; again made a very wide right traffic pattern. I continued with the left traffic pattern as we were well behind the faster aircraft by that time. I made an abbreviated pattern and attempted to contact the other aircraft several times; with no luck. I made a normal landing; well before the other aircraft and observed it perform another low approach from a right hand traffic pattern. It was still conducting low approaches as I taxied back to the hangar.The problem arose due to the other aircraft flying an improper and non-standard traffic pattern; as well as not communicating with other aircraft in the traffic pattern. I later learned from the FBO that owns that airplane that it was on a training flight; so the flight instructor was likely distracted by the student's performance and did not observe my airplane in the traffic pattern. After the last observed low approach; the other aircraft looked like it began using a left hand traffic pattern for the next couple of low approaches; so it makes me think they finally saw us and realized that they were using an incorrect pattern. The only other factor is that they were likely on the wrong radio frequency. A factor enhancing safety was that because my aircraft and the other aircraft are ADSB compliant; I was able to track him well with onboard equipment. This enhanced safety and situational awareness; especially after the incident.I have since contacted the FBO that owns the aircraft and reported the incident to their Chief Flight Instructor. I informed them of the correct CTAF and pattern so that the information can be passed along to their flight instructors for future use and to enhance the safety of operations at ZZZZ.

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.