Causes
While there are many reasons why a plane might crash into terrain, including bad weather and navigation equipment problems, it is claimed that pilot error is the single biggest factor leading to a CFIT incident.
Even highly experienced professionals may commit CFIT due to fatigue, loss of situational awareness, or disorientation. CFIT is considered a form of spatial disorientation, where the pilot(s) do not correctly perceive their position and orientation with respect to the Earth's surface.
The incidents often involve a collision with terrain such as hills or mountains, and may occur in conditions of clouds or otherwise reduced visibility. CFIT often occurs during aircraft descent to landing near an airport. CFIT may be associated with subtle equipment malfunctions. If the malfunction occurs in a piece of navigational equipment and it is not detected by the crew, it may mislead the crew into improperly guiding the aircraft despite other information received from all properly functioning equipment, or despite clear sky visibility that should have allowed the crew to easily notice ground proximity (compare tunnel vision).
Some pilots, convinced that advanced electronic navigation systems coupled with flight management system computers, or over-reliance on them, are partially responsible for these accidents, have called CFIT accidents "computerized flight into terrain".
Read more about this topic: Controlled Flight Into Terrain