LJ25 CAPT LANDED AT MIA BELOW MINIMUMS.

Narrative

FLEW A LIFEGUARD FLT FROM ZZZ TO MIAMI; FL. FO FILED THE FLT PLAN AND GOT WX. HE BRIEFED ME THAT THERE WAS NO WX UPON ARR IN MIAMI; AND DID NOT CHK INST NOTAMS DUE TO GOOD FORECAST WX. 1/2 WAY TO MIAMI; I RECHKED WX. I FOUND THE FORECAST FOR 1 HR BEFORE OUR ARR TO BE CLR AND VFR; AND 2 HRS BEFORE OUR ARR TIME TO BE OCCASIONALLY 1/4 MI FOG. MY FO SAID THERE WAS NO MENTION OF FOG IN THE BRIEFING. WE CONTINUED TO MIA; AND UPON ARR; THE WX DROPPED TO LESS THAN 1/8 MI AND NOBODY WAS GETTING IN. WE DIVERTED TO FT MYERS FOR FUEL AND A QUICK TURN. THE PATIENT HAD TO BE IN MIAMI; FL; FOR A TIME CRITICAL; SPECIALTY LIFE SAVING PROC IN 25 MINS. WE DEPARTED FT MYERS; FL; TO MIA; AND UPON ARR IN MIA; ATC TOLD ME THAT RWY 9R WAS CLOSED; THE XING RWY WAS LESS THAN 1000 FT RVR; AND 3 ACFT JUST LANDED RWY 9L AND 1 MISSED RWY 9L WITH 3000 FT RVR. ATC ADVISED ME THAT BEST VISIBILITY (3000 FT RVR) AND CHANCE OF GETTING IN WAS RWY 9L. ATC CLRED ME FOR ILS RWY 9L. I REMEMBERED A NOTAM ON RWY 9L THAT HAD TO DO WITH AN UNMONITORED LOC OR DME OUT; OR SOMETHING TO THAT NATURE. I BEGAN THE APCH (ILS RWY 9L); AND THE LOC WAS MILDLY ERRATIC ON SHORT FINAL. IT SETTLED DOWN APCHING MINIMUMS. I LANDED WITHOUT INCIDENT. WHILE TAXIING IN; I HEARD AIRLINES LOOKING FOR 5000 FT RVR ON ILS RWY 9L. I WONDERED WHY. I RECHKED MIA NOTAMS AFTER SHUTDOWN IN MIA; AND FOUND 'MIA RWY 9L ILS LOC UNUSABLE 1.2 NM/3.1 DME INBOUND' IN MIA NOTAMS. THAT EXPLAINED THE ERRATIC NEEDLE DURING SHORT FINAL. I LOOKED AT OTHER APCHS TO RWY 9L AND FOUND A GPS TO RWY 9L WITH 5000 FT RVR MINIMUMS. I ASSUME THE AIRLINES WERE USING THIS APCH. I JUST DON'T UNDERSTAND WHY APCH WOULD CLR ME FOR THE ILS RWY 9L WITH A NOTAMED OUT LOC FROM 1.2 NM TO 3.1 NM. IF THIS WAS THE CASE; HOW CAN THEY CLR ME FOR THE APCH? IF THEY WANTED ME TO BACK UP WITH GPS; I SHOULD HAVE BEEN CLRED GPS RWY 9L; ILS COURSE INOP. ALSO; WHY WOULD RWY 9L ILS BE TURNED ON IN LOW FOG WHEN LOC IS INOP FOR 1.9 NM INSIDE THE MARKER? THE FLT LANDED WITHOUT INCIDENT; AND PATIENT MADE IT TO THE HOSPITAL JUST IN TIME. IN RETROSPECT; RWY 9L WAS THE ONLY RWY WITHIN 75 MI OF THE HOSPITAL THAT HAD GREATER THAN 1000 FT RVR; AND HAD AIRPLANES LNDG ON IT.