Sequence of Events
The aircraft was conducting an Instrument Landing System (ILS) approach to runway 15 when it collided in-flight with static wires approximately 2 miles north of the runway. The wires were positioned in the aircraft's flight path and aligned directly with the ILS final approach course. At the time of the accident, the local control tower was closed.
Weather Conditions
Weather observations from the Otis Air National Guard Base (2155) reported: indefinite ceiling 100 feet sky obscured, visibility 3/4 mile, light rain and fog, temperature 59°F, dew point 58°F, wind from 170° at 14 knots gusting to 19 knots, and altimeter 29.96 inches Hg.
Pilot Reports
Three other aircraft had conducted the approach prior to N402BK. The pilots of those aircraft all reported encountering downdrafts and turbulence at approximately 500 to 700 feet MSL while on the final approach course. They noted that the downdrafts caused their airplanes to descend below the glide slope, requiring increased power or pitch adjustments to rejoin the glide path.
Probable Cause
The official findings state that the probable cause was the pilot's failure to maintain a proper glide path during an ILS approach, which resulted in a collision with power lines. Contributing factors were identified as adverse weather conditions including turbulence, downdrafts, and fog.