CMH LCL CTLR FAILS TO ISSUE TFC RESULTING IN TFC CONFLICT.

Narrative

WE WERE DEPARTING/LNDG TO THE E. THE WX WAS CAVU. I HAD JUST RELIEVED THE LCL CTLR MAYBE 2-3 MINS PRIOR TO WHEN THE PLT ASKED ABOUT THE ACFT THAT HE APPARENTLY JUST PASSED OVER. BY THE SOUND OF HIS VOICE; IT WAS OBVIOUSLY WITHIN AN UNCOMFORTABLE PROX. THERE WERE ONLY 2 ACFT ON FINAL AT THE TIME. BOTH HAD ALREADY BEEN CLRED TO LAND BY THE CTLR I HAD JUST RELIEVED. THERE WERE NO DEPARTING ACFT READY FOR TKOF. TFC SURVEY (MEDIA BROADCAST TFC RPTING) ACFT WERE FLYING THEIR NORMAL FLT PATHS. IN THIS CASE; WHERE THEY CROSS OUR FINAL; THEY ARE OUTSIDE THE FINAL APCH FIX; AND 500 FT BELOW THE OUTER RING OF OUR CLASS C AIRSPACE. THE PLT OF ACFT X; A PAYE; WHO WAS INBOUND FOR RWY 10R SAID SOMETHING LIKE 'WHO WAS THAT WHO JUST PASSED 300 FT BELOW ME?' AT THAT TIME HE WAS JUST OUTSIDE THE FAF (ARLIG); ON A VISUAL APCH. THE RWY 10R GS WAS OTS. NORMALLY ACFT ON A VISUAL APCH WILL STAY AT OR ABOVE THE GLIDE PATH; AND ARE THEREFORE AT LEAST 700 FT ABOVE THE STANDARD FLT PATTERN OF THE TFC SURVEY ACFT. HOWEVER; IN THIS CASE; THE PLT OF ACFT X WAS WELL BELOW THE NORMAL FLT PATH; AND THAT PUT HIM BELOW THE LOWER LIMIT OF THE OUTER RING OF OUR CLASS C AIRSPACE (2500 FT MSL). HE WAS AT 2300 FT MSL WHEN TYPICALLY HE WOULD'VE BEEN AT OR ABOVE 2700 FT MSL. THE TFC SURVEY ACFT FLY AT 2000 FT MSL. I HADN'T CONSIDERED THE IMPLICATIONS OF THE GS BEING OTS. I WAS NOT EXPECTING THE PLT TO BE SO LOW. I DO NOT RECALL HEARING ANY CONFLICT ALERT AUDIBLE ALARM. I BELIEVE THAT HAD I HEARD A CONFLICT ALARM ACTIVATE; THAT WOULD HAVE CERTAINLY BROUGHT MY ATTN TO THE SIT. THERE WAS 1 OTHER CTLR (WORKING GND CTL); AND A SUPVR (WORKING CLRNC DELIVERY) IN THE CAB. HAD THEY OBSERVED THE SIT (ESPECIALLY IF CONFLICT ALERT WAS BLARING); I FIRMLY BELIEVE THEY WOULD HAVE SAID SOMETHING. MY INABILITY TO SEE THE ENTIRE ARPT MOVEMENT AREA WAS A PRIMARY DISTR FOR ME. I DIDN'T OBSERVE ANY CORRECTIVE ACTION TAKEN BY THE PLT; NOR DID THE PLT ADVISE OF ANY CORRECTIVE ACTION. FACTORS AFFECTING THE QUALITY OF HUMAN PERFORMANCE: I AM UNABLE TO OBSERVE VAST EXPANSES OF THE ARPT MOVEMENT AREA WHILE STANDING IN ANY ONE LOCATION IN THE TWR CAB. TO BE ABLE TO SEE ADEQUATELY; I UTILIZE A 14