A cessna 172 pilot reported that while flying downwind for landing an RV8 pilot flew into the patter...

Narrative:

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.

Original NASA ASRS Text

Title: 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.

Narrative: 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.

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.

Attributes
ACN	1490548
Time
Date	201710
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Route In Use	None Visual Approach
Flight Plan	None
Aircraft 2
Make Model Name	RV-8
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Route In Use	Visual Approach None
Flight Plan	None
Person 1
Function	Instructor Pilot Not Flying
Qualification	Flight Crew Commercial Flight Crew Flight Instructor Flight Crew Instrument
Experience	Flight Crew Last 90 Days 90 Flight Crew Total 670 Flight Crew Type 600
Events
Anomaly	Conflict NMAC
Miss Distance	Horizontal 200 Vertical 100

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.