Small Aircraft; High Wing; 1 Eng; Fixed Gear
Flight Crew Flight Instructor; Flight Crew Instrument
Flight Crew Last 90 Days 200; Flight Crew Total 415; Flight Crew Type 370
Communication Breakdown; Situational Awareness
Conflict NMAC
Flight Crew Took Evasive Action
Human Factors
I was instructing a Student Pilot on traffic patterns and full stop taxi back landings this morning at IYS off of Runway 04. We had been working in the pattern for over 30 minutes; making all radio calls: 'upwind; crosswind; downwind; base; and final'. For over 30 minutes we were the only ones in the traffic pattern and landing at the airport. We made frequent position radio calls the entire time we were there. We were on our 4th landing; on the final leg for Runway 04; when a multi engine aircraft overtook us from behind and underneath. Not only had we made a 'turning final' call but I also personally made a 'short final' call. We were already established on a stable approach and on glide slope. We had not heard any radio calls at all from any other aircraft for PAWS or the surrounding area while on that lap in the pattern. We believed we were the only ones in the traffic pattern or attempting to land at the airport.After I made my short final call; I saw them at my 2 o'clock position underneath us. They heard my call and finally made a radio call with their position; and made a hard right 360 to avoid traffic. We started a shallow climb on our present heading; responded over the radio and informed them we would continue our final heading to also avoid conflict. We came to a full stable stop on Runway 04 and taxied to the parking area where I shut down the plane and had my student and myself take a break. The other aircraft continued to fly multiple approaches; only ever making a call when on their own short final. We waited for them to leave the area before starting the plane up again; taking off; and leaving that airport.
Light aircraft flight instructor reported an NMAC on final approach at IYS airport.