THIS METRO CAPT RPTS THAT; DUE TO THE SEATING POS OF A POI CONDUCTING A RTE CHK; THE POI THOUGHT THAT THE FLC HAD FLOWN BELOW MINIMUMS BEFORE HAVING VISUAL CONTACT WITH THE RWY ENVIRONMENT. THE RPTR ALSO STATED THAT THE WINDSHIELD DEFROSTER SYS DOES NOT CLR THE WINDSCREEN COMPLETELY.

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WITH OUR COMPANY'S POI ON BOARD GIVING A RTE CHK WE MADE AN APCH TO ANCHORAGE ILS RWY 6R WITH 2400 FT RVR. OUR VISIBILITY REQUIREMENT IS 1800 FT SO WE EXPECTED TO BREAKOUT BEFORE DECISION HT. AT DECISION HT WE IDENTED THE APCH LIGHTS AND CONTINUED TO 150 FT ABOVE TOUCHDOWN ZONE WHERE WE IDENTED THE RWY BY REILS; CTRLINE AND SURFACE. THE OBSERVER SEAT IN THE METRO IS THE FRONT R PAX SEAT WHICH HAS THE CLOSET DIRECTLY IN FRONT OF THE OBSERVER. THIS COMBINED WITH WINDSHIELD FRAME SUPPORTS AND AREAS OF OBSCURATION CAUSED BY WINDSHIELD FROST OBSCURED THE POI'S VIEW FORWARD TO CONFIRM THAT WE HAD THE RWY IN SIGHT. EVEN THOUGH WE HAD THE DEFROST FAN ON HIGH WE COULDN'T KEEP THE WINDSHIELD COMPLETELY ICE/FROST FREE. THE ONLY INST VISIBLE TO THE INSPECTOR WAS MY ALTIMETER AND AS SUCH I UNDERSTAND WHY HE THOUGHT WE WERE BELOW MINIMUMS. CAUTION SHOULD BE USED DURING RTE CHKS TO MAKE SURE THE INSPECTOR HAS A SAFE VIEWING POS FOR ALL OPS. ANOTHER METHOD OF CLRING THE WINDSHIELD SHOULD BE FOUND FOR THE METRO TO AVOID FUTURE PROBS. WE HAD INCLUDED A DSCNT FROM DECISION HT WITH LIGHTS IN SIGHT IN OUR BRIEFING OF THE APCH. AT NO TIME DID I OR MY CREW FEEL THAT WE WERE IN ANY DANGER.