Two flight instructors in different aircraft reported they were involved in an NMAC in the pattern at APA when one of the aircraft cut off the other.
Synopsis
Two flight instructors in different aircraft reported they were involved in an NMAC in the pattern at APA when one of the aircraft cut off the other.
Narrative
The problem arose when I began teaching a standard approach to landing from the traffic pattern to Runway 17R. My student had only been in the program a week and was up for his first flight in the traffic pattern. Due to this I became task saturated teaching as he'd told me he'd read over the required material but was having a hard time contextualizing without seeing it in practice during our preflight briefing. I told him I would take over the first lap in the pattern in the downwind and explain everything I was doing until we'd landed. The issue occurred due to me getting fixated on teaching though an approach and I mistakenly got in front of my traffic to follow. After being cleared to land; I temporarily lost sight of the assigned traffic to follow due to teaching and then mistakenly believed them to have already landed. I did have the traffic in sight when I turned base but misjudged them to be set up to land on the parallel runway and continued to talk though my approach to my student.Once I'd turned final; the traffic now behind and above me called a go around after informing ATC they'd been cut off. With the mistake already made I continued to land so as to not cause any further risk to either plane since without being able to see behind me I could only assume they were climbing. At this point I was unsure of how close we were but I do not remember TCAS going off.The human factor that likely contributed to the quality of my performance the most is an abnormal amount of stress from my personal life. The instability in my life has caused me to not be getting the most restful sleep and I was likely more fatigued than I felt which could have also affected my judgement of the situation. A solution to this mistake is to schedule fewer high workload flights a day until my stress level is lower. Also in the future I will double check with ATC about my traffic to follow if I have even a shadow of a doubt about who I'm following.
Second reporter narrative
After several touch and goes in the traffic pattern; my student and I experienced a near miss due to an aircraft turning an early base-to-final. Despite being in contact with Tower and reporting us in sight twice; an aircraft turned towards Runway 17R on a mile base to final while we were on a one mile final.We had the necessary clearance and were lined up on the correct runway when our ADS-B system alerted us of traffic. I nearly disregarded the alert since they occur frequently in a busy pattern. Instead; I noticed the depiction showed a target at the same altitude turning towards us. I looked to see where it was and saw the other aircraft flying directly towards us; descending slightly lower.I immediately took the flight controls and initiated a go-around. I made the decision to overfly the parallel Runway 17L; as we were in a low wing and I wanted to maintain visual contact with the aircraft in the event that they initiated their own go around.After notifying Tower of the near miss; we were sequenced back in to the pattern and had an uneventful conclusion to the rest of the flight.I was instructed to call the APA Tower Cab; and spoke with the Controller at the time of the event. The Tower Supervisor reviewed the data and determined that the aircraft had mistakenly turned in after reporting us in sight on the tapes. The Supervisor notified me that the data had shown us within +/-200 feet of each other; and a collision being likely within seconds had evasive action not occurred.I used this as a teachable moment for my student and myself; as it is easy to become complacent of traffic alerts in the pattern. It also stresses the importance of honest 'in sight' reports.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.