Narrative:

I was conducting a multi-engine commercial end of course stage check when we had a near mid-air collision with another aircraft that was on the ILS at the same time as us. The sequence of events began with me vectoring the student onto the ILS at 3;500 ft. I told her to proceed direct to the IAF at 3;500 ft so we could practice a hold entry. At this point we were south of final approach course. She proceeded direct to the IAF and entered the hold. From there we attempted to intercept the glideslope and follow it down. We were approximately 3/4 scale vdi deflection low (above the glideslope) and about 1/4 scale CDI deflected left at this point. I was monitoring CTAF and heard two airplanes: one who was also on the ILS and another in closed traffic for runway [opposite direction]. I immediately began looking for both of them. I might have made one radio call outside the FAF; unfortunately I don't recall where. A few minutes later; we were about 1 NM past the FAF and still slightly above glideslope when we received a radio call from the other aircraft on the ILS what our intentions were (his exact words were; 'twin prop at ZZZ; what's your plan'). I said that we were going to do the ILS to a missed approach. At the time I believed that the aircraft talking to me was the aircraft in closed traffic. I still had not seen the other aircraft on the ILS yet. He then informed me that we had overtaken him on the ILS. His exact words were 'you basically dropped in on top of us on the ILS.' in his later phone conversation with a chief instructor; the other pilot estimated that we had passed approximately 200 ft above him on the ILS; a distance estimate I was made aware of during a conversation with that same chief instructor. After hearing the call over the radio; I decided to not descend below pattern altitude on the ILS (I wanted to avoid further danger from the aircraft in closed traffic for the opposite direction runway) and informed the student to make her da 1;000 MSL and start the missed approach then. She complied and we flew back. I could've avoided this situation by being much more proactive on the radio than I was. This situation could've easily been avoided by better use of radios on CTAF to coordinate spacing on the approach and better situational awareness between the two pilots.

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Original NASA ASRS Text

Title: PA44 instructor pilot is informed by a C172 pilot that a NMAC occurred while both aircraft were practicing an ILS with the PA44 overtaking from above. The reporter never saw the other aircraft and states that his CTAF communications may have been lacking.

Narrative: I was conducting a Multi-Engine Commercial End of Course Stage Check when we had a near mid-air collision with another aircraft that was on the ILS at the same time as us. The sequence of events began with me vectoring the student onto the ILS at 3;500 FT. I told her to proceed direct to the IAF at 3;500 FT so we could practice a hold entry. At this point we were south of final approach course. She proceeded direct to the IAF and entered the hold. From there we attempted to intercept the glideslope and follow it down. We were approximately 3/4 scale VDI deflection low (above the glideslope) and about 1/4 scale CDI deflected left at this point. I was monitoring CTAF and heard two airplanes: one who was also on the ILS and another in closed traffic for Runway [opposite direction]. I immediately began looking for both of them. I might have made one radio call outside the FAF; unfortunately I don't recall where. A few minutes later; we were about 1 NM past the FAF and still slightly above glideslope when we received a radio call from the other aircraft on the ILS what our intentions were (his exact words were; 'Twin prop at ZZZ; what's your plan'). I said that we were going to do the ILS to a missed approach. At the time I believed that the aircraft talking to me was the aircraft in closed traffic. I still had not seen the other aircraft on the ILS yet. He then informed me that we had overtaken him on the ILS. His exact words were 'You basically dropped in on top of us on the ILS.' In his later phone conversation with a Chief Instructor; the other pilot estimated that we had passed approximately 200 FT above him on the ILS; a distance estimate I was made aware of during a conversation with that same Chief Instructor. After hearing the call over the radio; I decided to not descend below pattern altitude on the ILS (I wanted to avoid further danger from the aircraft in closed traffic for the opposite direction runway) and informed the student to make her DA 1;000 MSL and start the missed approach then. She complied and we flew back. I could've avoided this situation by being much more proactive on the radio than I was. This situation could've easily been avoided by better use of radios on CTAF to coordinate spacing on the approach and better situational awareness between the two pilots.

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.