C150 instructor pilot reported an near midair collision on approach to mio; a non-towered airport.

Narrative:

I was working with a student in his personal airplane. We were performing the GPS/RNAV 17 approach at mio. We were inside the final approach fix; ijedy descending from 2;500 feet MSL. My student; a private rated pilot; made the announcement we were 5 miles north at the final approach fix for the RNAV/GPS 17. A crop duster was departing 35 (winds were calm) and announced he had us in sight and he would be making a left turn to the west. I observed this airplane departing; and told my student that if necessary I would take control of the airplane but didn't think this would be necessary. About that time I observed a second airplane; a mooney directly below us and slightly to the right; estimated at 150-200 feet [from us]. He had made no calls up to this point. I made a call on the radio saying I had the crop duster [in] sight and a mooney on final; to let the crop duster know he had opposite direction traffic besides us. It was then the mooney made an announcement. He continued the approach and landed in front of us; causing us to go around. He apologized and said the he was on VFR flight following; that ATC did tell him he had traffic; but he thought we were just maneuvering. We had been on this approach since we intercepted mebie; IAF. I feel his reliance to ATC VFR flight following; his lack of seeing and avoiding and his improper pattern entry at a non-towered airport were contributing factors.

Original NASA ASRS Text

Title: C150 instructor pilot reported an NMAC on approach to MIO; a non-towered airport.

Narrative: I was working with a student in his personal airplane. We were performing the GPS/RNAV 17 approach at MIO. We were inside the final approach fix; IJEDY descending from 2;500 feet MSL. My student; a private rated pilot; made the announcement we were 5 miles north at the final approach fix for the RNAV/GPS 17. A crop duster was departing 35 (Winds were calm) and announced he had us in sight and he would be making a left turn to the west. I observed this airplane departing; and told my student that if necessary I would take control of the airplane but didn't think this would be necessary. About that time I observed a second airplane; a Mooney directly below us and slightly to the right; estimated at 150-200 feet [from us]. He had made no calls up to this point. I made a call on the radio saying I had the crop duster [in] sight and a Mooney on final; to let the crop duster know he had opposite direction traffic besides us. It was then the Mooney made an announcement. He continued the approach and landed in front of us; causing us to go around. He apologized and said the he was on VFR flight following; that ATC did tell him he had traffic; but he thought we were just maneuvering. We had been on this approach since we intercepted MEBIE; IAF. I feel his reliance to ATC VFR flight following; his lack of seeing and Avoiding and his improper pattern entry at a non-towered airport were contributing factors.

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.

Attributes
ACN	1651112
Time
Date	201905
Place
Locale Reference	MIO.Airport
State Reference	OK
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Cessna 150
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Route In Use	Visual Approach
Flight Plan	None
Aircraft 2
Make Model Name	M-20 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Person 1
Function	Pilot Not Flying Instructor
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 150 Flight Crew Total 8500 Flight Crew Type 200
Events
Anomaly	Conflict NMAC
Miss Distance	Horizontal 150 Vertical 200