DUE TO FMS PROGRAMMING; WX FACTORS (ICING); AND MULTI FUNCTION DISPLAY UNIT DISTR; ALT XING RESTR NOT MET.

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WE WERE AT FL290 ABOUT 40 MI SW OF OTT VOR ON THE GVE TRANSITION OF THE DUPONT 3 ARR. ZDC INSTRUCTED US TO CROSS OTT AT FL240. THE FO; WHO WAS FLYING; TOLD ME THE POINT AT WHICH HE WOULD START HIS DSCNT. THE POINT WAS BEFORE THE FMS COMPUTED DSCNT POINT; BUT BEYOND WHERE I WOULD HAVE STARTED. I WAS NOT CONCERNED; HOWEVER; BECAUSE I KNEW THE F100 COULD DSND AT A HIGH RATE; SHOULD WE GET BEHIND ON THE DSCNT. THE FO INITIATED THE DSCNT BY SELECTING A VERT SPD IN PROFILE MODE. ICING CONDITIONS AND A CABIN ALT CTL CHANNEL MULTI FUNCTION DISPLAY UNIT MESSAGE CAUSED SOME DISTR AND OUR DSCNT SEEMED TO SHALLOW OUT. I REMINDED THE FO OF OUR REQUIRED DSCNT RATE; AND HE SELECTED A DIFFERENT VERT MODE FOR THE AUTOPLT. APCHING OTT; WE WERE STILL ON PATH TO MAKE THE XING RESTR; BUT JUST BARELY. HOWEVER; I DID NOT ANTICIPATE THE DECREASED VERT SPD THE AUTOPLT USED AS WE APCHED FL240. WE CROSSED OTT AT FL243 AND CONTINUED DOWN TO FL240. ZDC DID NOT QUERY US ON OUR DSCNT OR XING. I COULD HAVE PREVENTED THIS INCIDENT BY SUGGESTING AN EARLIER DSCNT POINT TO THE FO. PADDING THE REQUIRED DISTANCE WOULD ACCOUNT FOR UNEXPECTED CONDITIONS DURING THE DSCNT. I ALSO WILL NOT ASSUME THE F100'S HIGH DSCNT CAPABILITY WILL ALWAYS BE AVAILABLE.