Narrative:

My student and I were coming in to land at the ZZZ airport on the 45 degree to the left downwind; runway xx. At the 4 mile point we heard a takeoff call of another aircraft. Their call was as such: 'aircraft Y; taking off runway xx' [and] nothing else. We never saw them takeoff or depart but the next radio call we heard from them was them calling turning left downwind runway xx. At this point we were also turning left downwind so I quickly looked to our left and they were turning into us and we're [now] on a collision course. I assumed flight controls from my student; took evasive action and turned a very wide downwind; let them go ahead; and we both landed unharmed.I feel [that] what could help diminish situations like this; other than us paying more attention to aircraft taking off when coming in on a 45 to the downwind; would be to standardize radio communications at pilot controlled airports and really try to enforce their use in training and everyday operations. If aircraft Y had specified that they were staying in the traffic pattern; my student and I would have been on heightened alert for aircraft turning from crosswind to downwind into us.

Google
 

Original NASA ASRS Text

Title: Flight Instructor reported an NMAC event with another aircraft turning to downwind at an uncontrolled airport.

Narrative: My student and I were coming in to land at the ZZZ Airport on the 45 degree to the left downwind; Runway XX. At the 4 mile point we heard a takeoff call of another aircraft. Their call was as such: 'Aircraft Y; taking off Runway XX' [and] nothing else. We never saw them takeoff or depart but the next radio call we heard from them was them calling turning left downwind Runway XX. At this point we were also turning left downwind so I quickly looked to our left and they were turning into us and we're [now] on a collision course. I assumed flight controls from my student; took evasive action and turned a very wide downwind; let them go ahead; and we both landed unharmed.I feel [that] what could help diminish situations like this; other than us paying more attention to aircraft taking off when coming in on a 45 to the downwind; would be to standardize radio communications at pilot controlled airports and really try to enforce their use in training and everyday operations. If Aircraft Y had specified that they were staying in the traffic pattern; my student and I would have been on heightened alert for aircraft turning from crosswind to downwind into us.

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.