INSTRUCTOR PLT ALERTLY ADVISED LAF TWR REGARDING THE POS OF A METROLINER ON A 3-4 MI FINAL; BUT NOT IN COM WITH THEM. ATC HAD ARR INFO ON THE METROLINER; BUT WAS NOT AWARE THAT IT WAS ON FINAL APCH; THAT CLOSE; AND STILL ON ZID FREQ. LAF ATCT DOES NOT HAVE RADAR FOR TFC SEQUENCING.

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I WAS FLYING WITH A STUDENT WORKING ON XWIND LNDGS ON RWY 23 AT LAF; WHEN THE PATTERN BEGAN TO FILL UP WITH TFC COMING IN TO LAND. TWR SWITCHED US TO RWY 28 (FAVORED RWY BY THE WIND) UNTIL EVERYONE ELSE LANDED. OUR TFC WAS CALLED AS THE SECOND CADET ON A 3 MI FINAL; WHICH WAS THEIR CORRECT POS. WE RPTED BOTH ON FINAL IN SIGHT AND WERE TOLD TO FOLLOW THE SECOND CADET. ABOUT 5 SECONDS LATER; TWR WAS TALKING TO SOMEONE ON THE OPPOSING (L) DOWNWIND; AND I SPOTTED WHAT APPEARED TO BE A METROLINER ON A HIGH 3 1/2 MI FINAL FOR RWY 28. WHEN I GOT A BREAK ON THE FREQ; I ASKED TWR; 'TWR; SMA X; WHO'S THE GUY ON A HIGH FINAL FOR RWY 28; ABOUT 3 1/2 MI OUT?' TWR MISUNDERSTOOD; AND THINKING THAT I HAD LOST MY TFC TO FOLLOW; RE-RPTED THEIR POS TO US. MY MISTAKE WAS NOT TELLING THAT IT APPEARED TO BE A METROLINER ON THE INITIAL CALL. I THEN RPTED THIS ON MY SECOND CALL; AND THEY SAID THEY WERE EXPECTING A METROLINER ANY TIME; BUT THEY WEREN'T TALKING TO HIM AND ASKED ME FOR HIS POS. I GAVE THEM HIS POS AS 'ABOVE SMA Z' (MY TFC TO FOLLOW) AND SLIGHTLY L OF THEM ON FINAL FOR RWY 28. ABOUT 5-10 SECONDS LATER (IT SEEMED LIKE A LONG TIME); THE METROLINER MADE HIS INITIAL CALL; APOLOGIZING FOR HIS LATE CALL; AND SAID THAT CTR HAD JUST GIVEN HIM A FREQ CHANGE. THIS IS A FAIRLY COMMON PROB HERE AT LAF. ZID FORGETS THAT WE HAVE A TFC PATTERN AND INTENSIVE STUDENT TRAINING HERE; AND VECTORS IFR TFC INTO OUR PATTERN. THEY CANNOT SEE ANYONE RELIABLY BELOW 4000 FT MSL; WHICH IS ABOUT 3500 FT AGL. THEY EITHER NEED TO TURN IFR INBOUNDS OVER TO OUR TWR EARLIER; OR WE NEED A RADAR HERE. THERE WERE 5 IN THE PATTERN AT THE TIME -- ME IN R TFC; AND 4 ON THE L SIDE; AND BOTH OF THE ONES ON FINAL AT THE TIME WERE FULL STOP. TWR MADE THE METROLINER GAR AND COME BACK INTO THE PATTERN AS ANYTHING ELSE WOULD HAVE MADE 3 OTHER AIRPLANES GAR. THIS MUST BE FRUSTRATING TO THE METRO CREW; SINCE THEY DIDN'T MAKE THE MISTAKE IN THE FIRST PLACE.