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

Bottom line

A contributing factor in many accidents is a distraction that diverts the pilot's attention from monitoring the instruments or scanning outside the aircraft. When a pilot becomes task saturated, there is no awareness of input from various sources, so decisions may be made on incomplete information and the possibility of error increases. By planning ahead, a pilot can effectively reduce workload during critical phases of flight and prevent erosion of performance.