A CRJ PIC INITIATES AN EARLY DSCNT ON THE VOR DME RWY 24 APCH TO RSW; FL.

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WE WERE ASSIGNED THE VOR DME 24 APCH TO RSW; FORT MYERS. WE WERE CLRED BY APCH CTL TO DSND TO 1600 FT MSL AND WERE VECTORED ONTO THE INBOUND COURSE OF 244 DEGS. BELOW APPROX 2500 FT MSL; WE WERE IN VFR CONDITIONS WITH VISIBILITY OF 3-5 MI. THE APCH CALLS FOR A DSCNT TO 660 FT MSL AT 7 DME (MORGN) FROM THE RSW (LEE COUNTY) VOR. THE PF MISUNDERSTOOD THE DME AND BEGAN A DSCNT TO 700 FT (AS WAS SET IN THE ALT PRESELECT FOR THE FLT DIRECTOR AND AUTOPLT) AT 9 DME. THE PNF WAS SEARCHING FOR THE FIELD OUT THE WINDOW AND DID NOT IMMEDIATELY NOTICE THE ERROR. THE PNF NOTICED THE ERROR MOMENTS BEFORE THE TWR QUERIED US ABOUT OUR ALT WHICH INDICATED LOW; BY THAT TIME 200-300 FT LOW. WE COULD VISUALLY IDENT 2 OR 3 TWRS AT OUR 12 O'CLOCK POS AND WE AGREED TO STOP THE DSCNT AND CLB ABOVE THE TWRS BEFORE STARTING BACK DOWN TOWARDS THE ARPT; NOW VISIBLE. BETTER CRM WOULD HAVE HELPED WITH THE PNF MORE CLOSELY WATCHING THE ACTIONS OF THE PF. ALSO; THE PF ANNOUNCING HIS INTENTIONS BEFORE CARRYING OUT THE ACTION WOULD HAVE HELPED PREVENT THIS PROB. SUPPLEMENTAL INFO FROM ACN 573210: MISREAD DSCNT POINT AT MORGN; ON VOR; STARTED DOWN TO APPROX 1400 FT THEN STARTED TO CORRECT AT ABOUT THE SAME TIME APCH QUERIED. WE DO SEVERAL APCHS A DAY; SEVERAL DAYS A WK AND SEVERAL MONTHS A YR. IT IS IMPERATIVE TO REMAIN VIGILANT.