What happened
While operating in instrument meteorological conditions and encountering turbulence, the pilot experienced significant difficulty interacting with the aircraft's touchscreen multi-function display. These interface challenges led to the accidental selection of an incorrect radio frequency. During the period when communication with air traffic control was interrupted, the aircraft descended below the assigned altitude, which was the minimum sector altitude. The descent continued until communication was eventually restored.
The investigation
The investigation focused on the pilot's workload and the impact of environmental conditions on cockpit interfaces. It was determined that the pilot was managing a high workload caused by the combination of turbulence, instrument meteorological conditions, and the pressure of feeling rushed. This high cognitive demand likely resulted in ineffective monitoring of flight instruments. The investigation also noted that the physical vibrations caused by turbulence can make touchscreen interfaces difficult to use, as the display moves independently of the pilot, often leading to increased input errors or the need to stabilize the hand against the screen edge, which risks accidental presses.
Findings
- Turbulence caused data entry difficulties on the touchscreen multi-function display, leading to an incorrect radio frequency selection.
- The pilot was likely experiencing high workload due to the demanding flight conditions, which contributed to a loss of situational awareness.
- Ineffective monitoring of instruments occurred as a result of the pilot's cognitive resources being stretched by multiple simultaneous tasks.
- An air traffic controller issued a terrain safety alert after communication was re-established, which likely prevented a controlled flight into terrain accident.