Aircraft disappearance in mountainous terrain

2 fatalities • Bigfork, United States of America • Flight

An aircraft vanished from radar shortly after being cleared to descend, later impacting a steep mountain slope during night flight.

What happened

Following instructions from air traffic control to descend from 12,000 feet to 10,000 feet, the aircraft disappeared from radar surveillance. Radar telemetry indicated the plane was maintaining an altitude between 11,900 and 12,000 feet for roughly six minutes before losing contact. The final recorded transponder data at 0221:03 showed an altitude of 11,800 feet, suggesting the descent had commenced. At the time of the disappearance, a radar blind spot caused by antenna site construction prevented further tracking. Despite repeated attempts by controllers to establish communication, the aircraft could not be reached.

Weather conditions at the destination included precipitation and an overcast layer between 7,000 and 7,500 feet. After approximately two months, wreckage was located. Evidence at the crash site suggested the aircraft flew a level path through broken treetops before striking a northwest-facing mountain slope at a 60-degree angle near the 5,600-foot elevation. Examination of an encoding altimeter faceplate recovered from the scene showed needle impressions suggesting an altitude of approximately 560 feet, though other components were too damaged for full analysis.

Findings

Investigation into the wreckage revealed no evidence of mechanical malfunction or failure prior to the impact. However, records regarding the pilot's recent activity indicated a period of significant exhaustion; the pilot was returning from a strenuous three-day work period and had been awake for roughly 20 hours. The accident occurred under night conditions involving mountainous terrain, trees, and clouds, which contributed to the loss of the aircraft.

Probable cause

The pilot failed to maintain sufficient clearance from the terrain due to factors including fatigue and difficult flying conditions.

Frequently asked questions

What happened in the 1998-04-11 Piper PA-46 (Malibu/Meridian/Mirage/Matrix/M-Class) accident near Bigfork, United States of America?

An aircraft vanished from radar shortly after being cleared to descend, later impacting a steep mountain slope during night flight.

Were there any fatalities in the 1998-04-11 Piper PA-46 (Malibu/Meridian/Mirage/Matrix/M-Class) accident?

The accident was fatal, resulting in 2 fatalities.

What aircraft was involved and where did it happen?

The accident on 1998-04-11 involved a Piper PA-46 (Malibu/Meridian/Mirage/Matrix/M-Class), registration N9247W, operated by CMSystems, at Bigfork, United States of America.

What was the probable cause of the accident?

The pilot failed to maintain sufficient clearance from the terrain due to factors including fatigue and difficult flying conditions.

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