C172 and PA28-181 flight instructors reported the C172 started takeoff run while the PA28 was on short final resulted in an NMAC requiring evasive action.
Synopsis
C172 and PA28-181 flight instructors reported the C172 started takeoff run while the PA28 was on short final resulted in an NMAC requiring evasive action.
Narrative
Instructional flight with student to demonstrate non-towered airfield operations to ZZZ. Runway XX pattern. Entered the pattern and landed on runway XX without incident. When holding short of runway XX; I gave the call to indicate we were holding short and asking if there was any incoming landing traffic. One aircraft reported they had begun their downwind to base turn. Interpreting that we would have enough time to take off ahead of the aircraft turning base; I directed the student to take runway XX for takeoff. However; the traffic that had reported base was much closer than expected; virtually short final. Having already taken the runway and begun rolling; we continued the takeoff in order to clear the runway as soon as possible; but the landing aircraft was already close enough that they instead conducted a go-around to avoid us maintain clearance. We then departed the pattern to the southeast. In retrospect; I should have allowed for some variance in traffic position reporting and timing; and continued to hold short of the runway to allow the traffic on base to continue and land before I took the runway to take off. This would have allowed adequate spacing for both ourselves and the landing traffic; and would have resulted in an uneventful takeoff. An additional human factor includes time pressure; as I wanted my student to have the time to perform multiple laps in the pattern to build confidence in non-towered airfield pattern procedures and landings. I should have been aware of how this time pressure could have influenced my perception of aircraft spacing in the traffic pattern and how it would have influenced my decision to take the runway despite not having a fully accurate picture of the positions of traffic in the pattern.
Second reporter narrative
My student and I were shooting the RNAV XY circle to Land RWY XX at ZZZ. Student was making calls every 2NM. There was an approach going when we entered the left down for RWY XX; the other plane was shooting the RNAV RWY XX. We were coordinated and they were far enough for us to complete the circle to land. When were turning base to final and we were on final 100ft MSL; there was a Cessna holding short of RWY XX. They decided to enter the runway and take off when we were on 100ft to final. I saw that and took over and told him hold short as we are on final; he decided to ignore us and continue taking off. I took control and went around. Aircraft Y continued taking off and was below us by 100ft; they were to our left so I side stepped to the right so we can avoid collision. They never made any other calls at all. At 1000ft; we continued flying runway heading and continued to climb to get out of the traffic pattern and clear the area. They decided to make left turn and almost hit another plane that entered the traffic pattern for left downwind for RWY XX. Still they didn't make any calls. Our flight was VFR but it was instrument flight so we were practicing approaches. I made calls on what how we are moving and I said to Aircraft Y that his actions were unprofessional and that he almost caused another Collison with another plane as well. Still no reply. I made last call that we are departing to the south east and switched to fingers; frequency 123.45. While flying back; same plane; was joking with another pilot and said that he almost had an incident and made the joke that he has to go back to pick up the left over pieces from the runway. I didn't say anything; but this was very unprofessional.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.