INSTRUCTOR PLT OF A C150 TOOK OVER THE FLT CTLS FROM THE TRAINEE WHEN IT APPEARED THAT A MOONEY 20 WAS CONVERGING ON FINAL IN THE TFC PATTERN; STOPPING DSCNT AND CLBING ON A XWIND HDG ABOVE TFC.

Narrative

I WAS TEACHING A STUDENT A LESSON ON LNDG AT IXD; ON MAY/SAT/97. WE WERE THIRD IN THE L-HAND PATTERN FOR RWY 17 WITH A C150 AND A PIPER WARRIOR. THERE WAS ANOTHER ACFT IN THE R-HAND PATTERN. AFTER WE TURNED XWIND; ANOTHER ACFT (A MOONEY) RPTED 6.3 DME TO THE N FOR LNDG. THE TWR ADVISED HIM OF THE TFC IN THE PATTERN; TOLD HIM TO CONTINUE TO THE AIRFIELD; REMAIN AT 2000 FT; AND HE WOULD 'FIT HIM IN SOMEWHERE.' THE PATTERN WAS FAIRLY BUNCHED UP; SO I TOLD MY STUDENT TO DO S-TURNS ON DOWNWIND SO THAT WE WOULDN'T HAVE TO EXTEND OUT AS FAR. IN SPITE OF THE S-TURNS; WE TURNED BASE APPROX 1 1/2 - 2 MI FROM RWY 17. THE TWR CLRED THE WARRIOR FOR A TOUCH- AND-GO; THEN ASKED THE MOONEY OF HIS POS. HE RPTED 3 DME N. THE TWR CLRED US #2 FOR TOUCH-AND-GO BEHIND THE WARRIOR. SINCE WE HAD TO EXTEND SO FAR N; MY STUDENT ELECTED NOT TO START HIS DSCNT UNTIL WE WERE IN BASE. AS WE PREPARED TO TURN FINAL; I CHKED FOR CONFLICTING TFC. WHEN I CHKED TO MAKE SURE THAT FINAL WAS CLR; I SAW THE MOONEY AT OUR ALT AND AT 2 - 3 O'CLOCK POS INSIDE 1/4 MI. I IMMEDIATELY TOOK CTL OF THE AIRPLANE AND INITIATED A STRAIGHT CLB TO THE W. I TOLD THE TWR THAT I HAD BROKEN OFF THE APCH BECAUSE OF CONFLICTING TFC. HE HAD NO IDEA WHY WE HAD TO DO SO AND DEMANDED AN EXPLANATION. I TURNED TO FLY A COURSE PARALLEL TO UPWIND AND CONTINUED TO CLB TO 3500 FT. I REQUESTED AND WAS GIVEN A TURN TO THE N TO DEPART THE AIRSPACE. I LATER ASKED FOR A FREQ CHANGE. THE TWR TOLD ME TO STAND BY. WHILE WAITING; THE CTLR SCOLDED THE OTHER PLT AND THEN RELEASED ME.