Skyhawk 172/Cutlass 172
Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument
Flight Crew Last 90 Days 90; Flight Crew Total 670; Flight Crew Type 600
Communication Breakdown
Conflict NMAC
Flight Crew Took Evasive Action
Human Factors; Airspace Structure
At ZZZ; Aircraft Y (RV-8) based out of ZZZ nearly collided with the aircraft I was operating (Aircraft X) on the downwind leg of the left traffic pattern for runway 36. My student and I had returned from an uneventful local instrument training flight in the area. After landing; we (my student and myself) elected to taxi back to the runway to practice landings in preparation for my student's check ride. Throughout the duration of our time in the traffic pattern; my student was making proper radio calls on CTAF. While in the pattern for our last lap on the downwind leg; Aircraft Y radioed on CTAF (ZZZ- Aircraft Y; left downwind 36). Aircraft Y made no prior calls to the aforementioned. I immediately radioed Aircraft Y for clarification of his position as he frequently enters the traffic pattern in a non-standard manner. With that; I looked out the left side of the aircraft; and saw Aircraft Y turning less than 100 feet below; and to the left of our aircraft. I took control of the aircraft and ensured separation would be maintained between our aircraft despite Aircraft Y making no effort to ensure proper traffic pattern entry or separation. Aircraft Y frequently performs inappropriate and dangerous takeoffs; landings; and maneuvers at or near. The owner/operator of Aircraft Y needs remedial training as he is an unsafe operator who frequently violates FARs and has blatant disregard for safety. There was no reason for him to enter the traffic pattern recklessly; and to risk not only his life; but the life of myself and my student.
A Cessna 172 pilot reported that while flying downwind for landing an RV8 pilot flew into the pattern without communicating his position or intentions causing a near miss.