Narrative:

During pattern training for a pre-solo student we were on short final for runway xx. The winds were favoring that runway; although they were mostly crosswind. A government helicopter was also in the traffic pattern and had just completed a practice ILS to the opposing runway. They had broken off their approach at 1000 feet and entered the right downwind for runway xx. The government helicopter alerted us that there was an aircraft on the left downwind to [the opposite direction] runway and they weren't talking to anyone. Prior to that radio call to us; the helicopter had made a call to that aircraft asking their intentions. There was no response. As we did our touch and go (with the correct radio calls) we noticed that this aircraft had turned to a base leg on runway yy and would be a traffic conflict with the government helicopter; now on a final to runway xx. We alerted the helicopter and they made a landing on the adjacent taxiway intersection. We had made our crosswind turn early in order to avoid the aircraft. At some point between then and us entering the downwind for runway xx; the helicopter called us on the radio to let us know that the aircraft was traveling fast on a new downwind for runway xx and would be a traffic conflict with us. I took the flight controls and elected for a 360 on the downwind in order to provide this faster aircraft some space. During the 360; we saw the aircraft approaching us rapidly and had to take evasive action to avoid him. We are not sure if this aircraft knew we were on the downwind; or even in his or her vicinity. The aircraft made a full stop taxi back at ZZZ and then departed for presumably their home field.

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Original NASA ASRS Text

Title: C172 flight instructor reported a NMAC with an aircraft that was not transmitting intentions on the CTAF frequency.

Narrative: During pattern training for a pre-solo student we were on short final for Runway XX. The winds were favoring that runway; although they were mostly crosswind. A government helicopter was also in the traffic pattern and had just completed a practice ILS to the opposing runway. They had broken off their approach at 1000 feet and entered the right downwind for Runway XX. The government helicopter alerted us that there was an aircraft on the left downwind to [the opposite direction] runway and they weren't talking to anyone. Prior to that radio call to us; the helicopter had made a call to that aircraft asking their intentions. There was no response. As we did our touch and go (with the correct radio calls) we noticed that this aircraft had turned to a base leg on Runway YY and would be a traffic conflict with the government helicopter; now on a final to Runway XX. We alerted the helicopter and they made a landing on the adjacent taxiway intersection. We had made our crosswind turn early in order to avoid the aircraft. At some point between then and us entering the downwind for Runway XX; the helicopter called us on the radio to let us know that the aircraft was traveling fast on a new downwind for Runway XX and would be a traffic conflict with us. I took the flight controls and elected for a 360 on the downwind in order to provide this faster aircraft some space. During the 360; we saw the aircraft approaching us rapidly and had to take evasive action to avoid him. We are not sure if this aircraft knew we were on the downwind; or even in his or her vicinity. The aircraft made a full stop taxi back at ZZZ and then departed for presumably their home field.

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.