THERE WAS NO WX RPRTG STN AT COATESVILLE, BUT APRX 25 MI ESE AT PHILADELPHIA, THE FORECAST WAS FOR OCNL CEILINGS OF 600'OVERCAST, VIS 3 MI WITH LGT RAIN SHOWERS & FOG. THERE WERE FLT PRCTNS FOR TURBC BLO 5000' DUE TO WND SHEAR, CEILINGS & VIS FREQ BLO 1000' & 3 MI WITH STRATUS, LGT DRIZZLE & FOG. DRG ARRIVAL, THE ACFT WAS VECTORED FOR A VOR RWY 29 APCH (ILSWAS OUT OF SVC). ON HIS 1ST ATTEMPT, THE PLT MADE A MISSED APCH. HE GOT VECTORS TO FLY THE APCH AGAIN & SAID HE WOULD PROCEED TO PHILADELPHIA, IF A LNDG COULD NOT BE COMPLETED. ON THE 2ND APCH, THE ACFT DSCNDD BLO RADAR COVERAGE AT 1800' MSL, APRX 3 MI ESE OF THE ARPT. SUBSEQUENTLY, IT CRASHED APRX 1 MI NNE OF THE RWY THRESHOLD, WHILE IN A STEEP NOSE DWN ATTITUDE. THE MAIN WRECKAGE CAME TO REST 44' NNE OF THE PRINCIPAL IMPACT POINT. NO PREIMPACT MECHANICAL PROBLEMS WERE FOUND. THE STABILATOR TRIM WAS NOTED IN THE FULL NOSE DWN POSITION; BUT THE SYS'S INTEGRITY WAS NOT MAINTAINED DRG THE ACDNT. WX STUDY INDCD CLD BASES WERE AT 900' MSL. MIN DSCNT ALT (MDA) FOR THE APCH WAS 1060' MSL; ARPT ELEV WAS 662'.