GA Instructor pilot and their student reported another aircraft in the pattern was not complying with non tower airport pattern procedures which resulted in an NMAC as well as conflicts with other aircraft in the pattern.
Synopsis
GA Instructor pilot and their student reported another aircraft in the pattern was not complying with non tower airport pattern procedures which resulted in an NMAC as well as conflicts with other aircraft in the pattern.
Narrative
Today Day 0 at XA45 am local. I was working on pattern work with my student today at ZZZ. During our pattern work; Aircraft Y was also working on pattern work today. The issues I observed were the Aircraft Y's unsafe pattern operations. The Aircraft Y consistently made unsafely low crosswind turns and low patterns in general. The Aircraft Y did 4 patterns like this with cross-wind turns at 200 ft. AGL and downwind legs at 600 ft. AGL.The first pattern I observed the Aircraft Y did was while we were holding short of Runway XX; the Aircraft Y's low crosswind turn caused them to cut off Aircraft Z in the pattern; and again on base to final. Aircraft Z had to go around. In the second pattern; the Aircraft Y took off after us and again turned a low crosswind turn 200 ft. AGL cutting us off and turning direct to us on downwind. So I asked the Aircraft Y if they had us in sight; and they responded they did have us in sight; as we proceed on downwind for a short approach the Aircraft Y cut us off on our base and I took flight controls from my student departed the pattern (this was our close encounter) and came back in on the 45.The Aircraft Y has now cut off 2 people in the pattern by flying an unsafe low pattern at a busy time at ZZZ. The next pattern the Aircraft Y flew was similar to the first 2; Crosswind turn at 200 AGL and pattern no higher than 600 AGL. This time another flight was in the pattern (I forgot the tail number but it was a low wing) they had a close encounter with the Aircraft Y and again called out the Aircraft Y on frequency. This is when the instructor of the Aircraft Y got on the radio and said 'his student was flying a proper pattern for a Aircraft Y and that he was doing just fine.' This is a MAJOR concern! The Aircraft Y pilot is teaching extremely unsafe pattern procedures to a student pilot at an extremely busy airport such as ZZZ with a flight school as well as other training traffic.
Second reporter narrative
I was flying with my instructor in Aircraft X practicing power off 180s on Runway XX at ZZZ. The Aircraft Y was also in the pattern but flying extremely low while cutting off other aircraft including us. He would takeoff Runway XX and turn crosswind at about 200 ft. AGL and before crossing Runway X-XY. He was flying roughly a 600 ft. AGL pattern. We had to break out of pattern right before I was going to turn base just to miss him. He also started taxiing onto the runway before other flight school planes were even on the ground during landing. This all started around XA45am CST and ended around XB15am CST.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.