What happened
During an instrument approach using the Instrument Landing System, the flight crew prepared for the arrival while navigating through poor visibility, characterized by a 100-foot broken cloud layer and 2 miles of visibility. The approach path extended over water, and the immediate area of the accident was obscured by dense fog. Prior to this flight, two smaller aircraft had successfully completed the same approach.
As the aircraft descended, the first officer provided altitude callouts until the plane reached 200 feet above the decision height. At this stage, the captain inquired about visual references. The first officer reported seeing ground contact and noted the arrival at decision height. The captain then identified the approach lights, which the first officer confirmed. Following this, the captain reduced engine power to flight idle. Approximately four seconds later, an attempt to increase power was made, but the engines failed to respond in time to prevent the aircraft from descending into the water. The impact occurred approximately 2,000 feet from the runway, where the aircraft also struck several approach light stanchions.
Findings
Investigation into the descent revealed that the crew ceased altitude callouts once the approach lights were sighted. Crucially, the captain continued the descent below the established decision height without meeting the necessary criteria for a visual approach. It is believed that the lack of visible ground references may have induced a featureless terrain illusion, leading the pilot to believe the aircraft was at a higher altitude than its actual position. No mechanical issues were identified that would have prevented the aircraft from operating normally.