ACR-MLG BEING VECTORED FOR VISUAL APCH WAS DESCENDED BELOW MVA AND INTO CONFLICT WITH ACR-LGT ON ILS APCH.

Narrative

THE WX WAS RPTED VFR 20 SCATTERED; 250 SCATTERED. ONE ACFT VECTORED FOR ILS 4R; THE OTHER VECTORED FOR VISUAL APCH TO 4L. CLOUD LAYER MOVED IN. THE SEVERITY OF THE CLOUD LAYER WAS NOT MADE CLEAR. ATC WAS MISTAKEN AS TO THE VMA IN THE AREA AND DSNDED ACFT ON VISUAL APCH TO WHAT HE THOUGHT WAS MVA IN ORDER TO GET BELOW CLOUDS. THE SEP BTWN ACFT ON VISUAL APCH AND ACFT ON ILS APCH WAS SUBSEQUENTLY LOST. THIS INFO CAME TO LIGHT AFTER NTAP. IN THE CTLR'S JUDGEMENT; SEP WAS NOT LOST. SEP WAS ALSO LOST BTWN THE ACFT ON VISUAL APCH ON AND TERRAIN. THE SOLUTION TO THE PROB IS TO MAKE CTLRS MORE AWARE OF WX AND HOW QUICKLY AND SEVERELY IT CAN MOVE IN. ADDITIONALLY; THE ACFT ON VISUAL APCH NEVER MADE ANY COMMENT ABOUT THE CLOUDS; WHICH LED THE CTLR TO BELIEVE THE CLOUDS WERE JUST A SCATTERED LAYER AND NOT A FACTOR TO A GOOD; SAFE VISUAL APCH. THE PLT WAS AWARE THAT HE WAS ON VECTORS FOR THE VISUAL APCH. ALSO; TRNING SHOULD BE GIVEN TO CTLRS TO REFRESH MEMORIES ABOUT MVA'S; AS SOMETIMES WE TEND TO DO THINGS BY ROTE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR CTLR WAS VECTORING AN ACR MLG FOR A VISUAL APCH TO RWY 4L AND; THINKING THE MVA WAS 1500' WITH A SCATTERED CLOUD LAYER AT 2000'; DSNDED THE MLG TO 1500' IN AN AREA OF 1800 MVA. THAT WAS ERROR #1. THEN; AS THE MLG APCHED THE FINAL APCH COURSE FOR RWY 4L AND THE ACR LGT ON ILS RWY 4R; STILL NOT IN THE CLOUDS; RADAR SEP WAS LOST BETWEEN THE TWO WHEN THE MLG ENTERED MORE CLOUDS AND LOST SIGHT OF THE LGT. THIS SYSTEM ERROR OCCURRED MAINLY BECAUSE THE CTLR CONTINUED TO TRY TO CONDUCT VISUAL APCHS AFTER THE WX HAD DETERIORATED TO THE POINT THAT VISUAL APCHS COULD NOT WORK.