DCA85AA035

Drg arr, aprx 12 mi south of the final apch fix (faf), flt 1808 was clrd for an ILS rwy 4 apch. Aprx 3 min later, ATC controller (ctlr) noted acft was tracking east of the localizer (LOC) course. He asked if the flt was rcvg the ILS LOC. Capt replied 'not yet we haven't intercepted.' The ctlr then stated 'roger, turn left hdg 340, show you slightly rgt ofit.' Aprx 45 sec later, as the acft was crossing the LOC at the faf with a large intercept angle, the capt acknowledgedrcvg it. The acft contd past the faf at a relatively fast speed, but dscndg very slow. Also, it contd left of the LOC, then crossed back to the rgt & went abv, then blo the glide slope. Subsequently, the acft hit trees 4007' short & 440' rgt of the rwy. No preimpact part failure/malfunction was fnd. There was evidence that crew coordination was not consis-tently practiced among company crewmembers drg routine opns. Prev inv revealed Beech 99 acft had cockpit noise lvl of up to 97 db. FAA surveillance was affected adversely by lack of manpwr. Ovrall exp lvl of company plts reduced by turnovr.