Distractions, task prioritization, loss of situational awareness, or disorientation.

Bottom line

A distraction that diverts the pilot's attention from monitoring the instruments or scanning outside the aircraft is a contributing factor in many accidents. Fatigue, stress, and work overload can cause a pilot to fixate on a single perceived important item and reduce an overall situational awareness of the flight. When a work overload situation exists, a pilot needs to stop, think, slow down, and prioritize.