Background
An incident involved a pilot operating in instrument meteorological conditions and turbulence. The pilot experienced difficulties entering data using the aircraft's touchscreen interface. Research has documented that touchscreens can increase data entry errors and slow interaction times during turbulence.
Data Entry Difficulties
The pilot's data entry difficulties were consistent with studies on touchscreen interfaces. During turbulent conditions, the display may move or vibrate independently of the pilot's body, which is also vibrating. A study by Dodd and others (2014) found that in moderate turbulence, pilots took over two minutes longer to complete a task compared to no turbulence. Stabilizing the hand on the screen edge, although necessary, can also increase the risk of accidental presses on the screen's edge (Coutts and others, 2019).
Ineffective Monitoring
The pilot was experiencing high workload, likely due to operating in instrument meteorological conditions, turbulence, encountering data entry difficulties, and feeling rushed. This high workload likely resulted in the pilot not initially noticing a frequency change nor the continued descent and descent below the assigned altitude, which was the minimum sector altitude. Workload is defined as the sum of task demands placed on an individual's cognitive resources. Once cognitive resource limits are reached, performance declines with increased error rates and delayed responses, leading to cognitive overload. During high-workload periods, monitoring flight instruments can degrade due to other tasks requiring attention, potentially leading to undetected errors (Flight Safety Foundation, 2014). A study on controlled flight into terrain (CFIT) by the International Civil Aviation Organization, Flight Safety Foundation, and the U.S. Federal Aviation Administration found that two-thirds of all CFIT accidents result from altitude error or lack of vertical situational awareness. Although the pilot reported coping well, pilots are often unaware that their monitoring performance has degraded, subsequently affecting situational awareness.