Cessna 152
Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Commercial
Flight Crew Last 90 Days 40; Flight Crew Total 256; Flight Crew Type 197
Situational Awareness
ATC Issue All Types; Conflict NMAC
Flight Crew Took Evasive Action
Human Factors; Procedure
I was approaching [the airport] to make a left downwind pattern for Runway 31L. As I did this I was instructed to follow a Cessna which I identified in front of me. While flying parallel to 31L; I was instructing my private student on what sort of distance we were looking for and performing our before landing checklist. I lost situational awareness temporarily and lost the Cessna; but believed I identified it further on making its base turn. I watched the aircraft pass by my wing and allowed about 30 seconds more to keep us separated. I then looked ahead of me and to my left to make sure I was clear of traffic before turning base. I instructed my student on what a proper base looked like before turning final. By then I still had not been cleared to land so I was about to query the Tower when another call came on saying they were on final with someone above them. Even though we have a parallel runway there was enough doubt in my mind I executed a missed approach; and banked to the right to stay clear of the traffic which I located under me and to my right. I exited the pattern and request instruction to rejoin. It was later I learned the Diamond I would come in close contact with was on a right base for the same runway at a different altitude and that is why I wasn't able to pick him up in my scan as I was focused on left downwind traffic. I believe the problem was caused by a variety of factors. One being that the other aircraft and I didn't see each other; and it is my opinion this close call could have been avoided if [ATC] had intervened when he saw two aircraft on base heading towards each other.
C152 instructor pilot reported a NMAC in the airport traffic pattern.