Narrative:

While on a left downwind for runway xx; tower issued instructions to switch to runway xy and contact tower on the frequency for the north runway. I complied and was then cleared to land on runway xy following an archer on short final. Our aircraft observed aircraft Y on a left base turning final and asked tower to confirm that aircraft was turning final for xx so we could ensure proper spacing before turning left base for runway xy. Tower did not verify traffic; but our aircraft was able to determine aircraft Y was in fact turning final for runway xx and we could execute our left base with proper spacing. Once established on a left base; tower asked us to say position. We reported a left base for runway xy. As we reported our position aircraft Y on final for runway xx began turning left and executing a climb away from the final course and toward our aircraft. Unaware of why aircraft Y was executing a climbing turn due to the other aircraft being on the frequency for the south runway; I queried tower of the intentions of aircraft Y. Tower again asked us to state position while aircraft Y continued toward our aircraft. The instructor on board aircraft Y and myself took action to avoid each other at this moment with aircraft Y passing directly below our aircraft. Tower again cleared our aircraft to land on runway xy. After landing; I contacted ground for an explanation on what had occurred leading to a conflict that should not have existed otherwise. I was told there was a mix-up in the tower between the two [similar aircraft] due to tower not having the other aircraft identify early enough to verify their exact location. Tower then stated they had resolved the confusion once our aircraft was on final for runway xy. Upon talking to the other instructor; it was found that tower had cancelled their landing clearance and instructed them to return to the downwind; but then re-amended instructions to turn base causing them to perform a 360 which; part way through; created a traffic conflict with the [aircraft] I was operating. I believe tower intended the instructions to return to downwind be issued to my aircraft when tower became confused. The cause of the problem was a confusion among separate tower controllers over which aircraft they had control over; causing instructions to be issued to the incorrect aircraft leading to a traffic conflict. Had both aircraft been on the same tower frequency; the confusion likely could have been resolved with no traffic conflict. More caution should be taken when switching similar make and model aircraft to separate tower frequencies when they are in the vicinity of each other and one aircraft will be crossing through the final approach course of a parallel runway while the other aircraft is flying on that final approach course. Radar services at [this airport] would also prevent confusion among controllers servicing a high volume of training aircraft of similar make and models.

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Original NASA ASRS Text

Title: Flight instructor reported a near-midair-collision in the traffic pattern due to possible ATC confusion with similar aircraft on different frequencies.

Narrative: While on a left downwind for runway XX; tower issued instructions to switch to runway XY and contact tower on the frequency for the north runway. I complied and was then cleared to land on runway XY following an Archer on short final. Our aircraft observed Aircraft Y on a left base turning final and asked tower to confirm that aircraft was turning final for XX so we could ensure proper spacing before turning left base for runway XY. Tower did not verify traffic; but our aircraft was able to determine Aircraft Y was in fact turning final for runway XX and we could execute our left base with proper spacing. Once established on a left base; tower asked us to say position. We reported a left base for runway XY. As we reported our position Aircraft Y on final for runway XX began turning left and executing a climb away from the final course and toward our aircraft. Unaware of why Aircraft Y was executing a climbing turn due to the other aircraft being on the frequency for the south runway; I queried tower of the intentions of Aircraft Y. Tower again asked us to state position while Aircraft Y continued toward our aircraft. The instructor on board Aircraft Y and myself took action to avoid each other at this moment with Aircraft Y passing directly below our aircraft. Tower again cleared our aircraft to land on runway XY. After landing; I contacted ground for an explanation on what had occurred leading to a conflict that should not have existed otherwise. I was told there was a mix-up in the tower between the two [similar aircraft] due to tower not having the other aircraft IDENT early enough to verify their exact location. Tower then stated they had resolved the confusion once our aircraft was on final for runway XY. Upon talking to the other instructor; it was found that tower had cancelled their landing clearance and instructed them to return to the downwind; but then re-amended instructions to turn base causing them to perform a 360 which; part way through; created a traffic conflict with the [aircraft] I was operating. I believe tower intended the instructions to return to downwind be issued to my aircraft when tower became confused. The cause of the problem was a confusion among separate tower controllers over which aircraft they had control over; causing instructions to be issued to the incorrect aircraft leading to a traffic conflict. Had both aircraft been on the same tower frequency; the confusion likely could have been resolved with no traffic conflict. More caution should be taken when switching similar make and model aircraft to separate tower frequencies when they are in the vicinity of each other and one aircraft will be crossing through the final approach course of a parallel runway while the other aircraft is flying on that final approach course. Radar services at [this airport] would also prevent confusion among controllers servicing a high volume of training aircraft of similar make and models.

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.