What happened
On the evening of the accident, Northeast Airlines Flight 946 departed from Boston, heading toward destinations in Lebanon, New Hampshire, and Montpelier, Vermont. After reaching a cruising altitude of 8,000 feet, the crew received clearance to begin an approach to Lebanon Airport, with instructions to maintain 5,000 feet and report passing through 6,000 feet. Shortly after radar services were terminated, the flight crew contacted the Lebanon Flight Service Station, where they were informed of a cloud ceiling of approximately 2,000 feet and visibility of 10 miles.
Rather than following the standard published instrument approach procedure, the crew performed an improvised maneuver involving a right turn followed by a left turn to intercept the inbound radial for the VOR station. The aircraft intercepted this radial roughly 8 to 10 miles northeast of the station while at an altitude of approximately 4,500 feet. During this descent, the crew failed to maintain the required minimum altitude of 2,800 feet m.s.l.
While approaching runway 25, the Fairchild struck trees on the side of a steep, heavily wooded mountain located just 57 feet below its summit. The impact caused the aircraft to break apart and ignite. The accident resulted in 32 fatalities (including two crew members and 30 passengers) and 10 injuries.
Findings
The investigation determined that the crash was caused by the crew initiating a descent toward the minimum altitude prematurely. This decision was based on navigational readings that suggested they were approaching the station, though they were actually navigating through an area of course roughness. Because the crew had deviated from the standard approach and lacked supplemental navigational aids, they were unable to accurately determine their exact position during the maneuver.