BELOW MINIMUMS IFR APCH.

Narrative

I BEGAN THE ILS TO RWY 27 TO HAGERSTOWN; WASHINGTON COUNTY ARPT; ON A PART 135 FLT. TWR RPTED VISIBILITY AS 1/2 MI; WHICH WAS PLENTY FOR THE APCH PER THE DEC/XX/94 APCH CHART I WAS USING. THE APCH CHART SHOWED 1/2 MI AS THE MINIMUM. UPON LNDG; I REVIEWED A NOTAM OBTAINED FROM A COMPUTERIZED WX SVC AND NOTICED THAT THE VISIBILITY REQUIRED FOR THE APCH WAS 3/4 MI. THE INCREASED VISIBILITY WAS BURIED INSIDE 8-10 LINES OF CHANGES TO THE APCH. I JUST MISSED IT. UPON CHKING WITH A PLT WHO USES ANOTHER TYPE OF CHART; I SAW THAT HIS CHART; ISSUED NOV/YY/94 (ALMOST A FULL MONTH BEFORE THE CURRENT CHART) ALREADY HAD THE CHANGE NOTED. MOST PEOPLE DON'T CHK THE NOTAMS FOR MY TYPE OF CHARTS UNLESS THEY'RE TAKING A CHKRIDE. IT IS EASY TO MISS THIS AND VIOLATE A REG UNWITTINGLY. ACTUAL VISIBILITY AT DECISION HT WAS LESS THAN 1 MI. IF THIS WERE A PART 91 FLT; THERE WOULD NOT HAVE BEEN A PROB. HOWEVER; UNDER PART 135; AN APCH CANNOT BE INITIATED UNLESS VISIBILITY IS AT OR ABOVE MINIMUMS; WHICH IN THIS CASE WAS 3/4 MI. NOTE: I DID HAVE MY TYPE OF CHART NOTAM IN MY POSSESSION DURING THE APCH AND HAD REVIEWED IT BEFORE THE FLT. HOWEVER; THE INCREASED VISIBILITY AND DECISION HT WERE 'BURIED' INSIDE NUMEROUS OTHER CHANGES AND I JUST OVERLOOKED IT.