GABRIELS, NY, USA
N55000
BEECH 1900C
ON IFR ARRIVAL, FLT 4821 WAS CLEARED TO INTERSECTION 17 NE OF AIRPORT AT 6000', THEN FOR ILS RUNWAY 23 APPROACH. RADAR SERVICE WAS TERMINATED 6.5 EAST OF INTERSECTION. RADAR DATA SHOWED THAT FLIGHT CROSSED & THEN BRACKETED LOCALIZER. FLIGHT INTERCEPTED GLIDE SLOPE FROM BELOW ABOUT 7 MI OUTSIDE OF OUTER MARKER & THENCE DEVIATED ABOVE GLIDE SLOPE. ABOUT 2 MILES OUTSIDE OF MARKER, FLIGHT WAS AT A FULL FLY DOWN DEFLECTION WHEN IT ENTERED A DESCENT VARYING FROM 1200 TO 2000 FPM. AIRCRAFT STRUCK WOODED MOUNTAIN TOP 2.0 MI INSIDE OF OUTER MARKER (3.9 MI FROM RWY) AT ELEVATION OF 2280'. MINIMUM ALTITUDE AT MARKER WAS 3600'. GLIDE SLOPE ELEVATION AT POINT OF IMPACT WAS APRX 2900'. EVIDENCE WAS FOUND OF INADEQUATE ELECTRICAL GROUND PATH BETWEEN RADOME & FUSELAGE WHICH, WHEN COMBINED WITH EXISTING WEATHER CONDITIONS, MAY HAVE PRODUCED ELECTROSTATIC DISCHARGE (PRECIPITATION STATIC). ALTHOUGH POST-ACCIDENT TESTS WERE NOT CONCLUSIVE, THE SAFETY BOARD BELIEVES THAT THE GLIDE SLOPE INDICATIONS MIGHT HAVE BEEN UNRELIABLE DUE TO PRECIPITATION STATIC INTERFERENCE.
FAILURE OF THE CAPTAIN TO ESTABLISH A STABILIZED APPROACH, HIS INADEQUATE CROSS-CHECK OF INSTRUMENTS, HIS DESCENT BELOW SPECIFIED MINIMUM ALTITUDE AT THE FINAL APPROACH FIX, AND FAILURE OF THE COPILOT TO MONITOR THE APPROACH. FACTORS RELATED TO THE ACCIDENT WERE: WEATHER CONDITIONS AND POSSIBLE PRECIPITATION STATIC INTERFERENCE, CAUSED BY INADEQUATE GROUNDING BETWEEN THE RADOME AND FUSELAGE THAT COULD HAVE RESULTED IN UNRELIABLE GLIDE SLOPE INDICATIONS.
Source: NTSB Aviation Accident Database
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