What happened
During a night flight, the aircraft overflew the Shannon estuary and proceeded north at an altitude of 6,000 feet. Approximately forty-five minutes later, the captain disengaged the automatic pilot system to initiate a manual descent. After passing through the final cloud layer, the crew could see the ground but failed to realize that their altitude was insufficient for safe passage. The seaplane struck the slope of Mt Brandon with its right wing, which caused the aircraft to stall and crash in flames southwest of Brandon village. The accident resulted in ten fatalities, including the captain, while fifteen other occupants were injured.
Findings
The official investigation identified that navigation was conducted using compass headings and loop bearings on a ground radio station, without requesting QTE bearings from the station. The crew did not detect their deviation from the required track, a failure attributed to the "Night Effect," a known error in radio direction-finding apparatus around sunset and sunrise that can be undetectable even by experienced operators. Contributory factors included a strong south-westerly wind that caused the aircraft to arrive thirty minutes ahead of schedule, a subsequent shift in wind direction from south-west to north-west near Shannon, and the pilots' reliance solely on loop bearings for radio assistance while excluding direction signals from the ground station.