OPPOSITE DIRECTION APCH MTR Y HAD LTSS FROM ACR X. SYS ERROR.

Narrative

ACR X WAS READY FOR IFR DEP OFF RWY 17. INBOUND TFC WAS NUMEROUS MTRS ON PRACTICE ILS APCHS TO RWY 35. I WAS THE LCL CTLR MONITORING AN OJT (TRAINING) SESSION. THE TRAINEE REQUESTED AN IFR RELEASE FROM FSI APCH AND WAS GIVEN A RELEASE REF AN MTR ON APCH AND A VOID TIME. THE VOID TIME WAS NOT WRITTEN DOWN. (I DID NOT HEAR THE CONVERSATION. INTERPHONE CONFIGN MAKES IT DIFFICULT TO MONITOR). THE TRAINEE ADVISED THAT ACR X WOULD BE AFTER MTR AND THAT MTR WOULD BE TURNED EARLY TO FACILITATE ACR X DEP AND WAS GIVEN CLB OUT INSTRUCTIONS FOR MTR. ADDITIONAL TFC WAS AN MTR Y ON A SURVEILLANCE APCH TO RWY 35. WE WERE TOLD THAT HE WAS AT 7 MIL. ACR X WAS CLRED FOR TKOF (THE VOID TIME HAD PASSED). BEFORE ACR X WAS AIRBORNE; FSI APCH CALLED FOR CLRNC ON THE SURVEILLANCE AT 4 MI. THIS WAS LESS THAN 1 MIN AFTER GETTING THE 7 MI RPT. FACTORS: LAWTON TWR DOES NOT HAVE RADAR; VISIBILITY WAS REDUCED DUE TO HAZE; TRAINING IN PROGRESS; AND POOR INTERPHONE ARRANGEMENT. SUGGESTIONS TO PREVENT RECURRENCE: IMPROVE COM EQUIP AT LAWTON (SCHEDULED FOR FALL 1992). CLARIFY INFO -- BOTH TWR AND APCH (DISCUSSED BTWN INSTRUCTOR AND TRAINEE; LESSONS LEARNED).