Evaluation of human performance using touch screen displays in cockpit environment
Touchscreen technologies are making their way into aircraft flight decks as a means for pilots to view and interact with flight data. However, these touchscreens are often placed at arm’s length from the pilot, and all aircraft can experience turbulence. Even without turbulence, helicopter pilots in particular can be exposed to high levels of vibration caused by rotor movements. These factors may adversely impact touchscreen usability for the flight deck environment. In static conditions, touchscreens have been found to have higher throughput values, a performance measure that combines speed and accuracy (based on Fitts’s Law), compared to other pointing devices that are practical for the cockpit environment. This study provides throughput and error rate values under helicopter vibration conditions, to inform whether these devices still provide adequate performance under these conditions. In addition, a hand support method recommended by the standard SAE ARP60494 was tested, to indicate whether it improves usability under vibration. 24 participants performed a multidirectional selection task, as defined in the standard ISO 9241, using four different target sizes and three different distances between targets. Independent variables were: target size, distance between targets, vibration/no-vibration, hand support/freehand, type of screen, and position of screen. Two of the screens tested were avionic touchscreen prototypes, while the other two were consumer touchscreens. The touchscreens were placed in one of two positions: one representative of the Primary Flight Display (PFD, which is located on the main instrument panel), and the other representative of a Multi-Function Control and Display Unit (MCDU, which is located on the pedestal). This study provides values that quantify the impact of vibration on target-selection performance and error rate, when using a touchscreen. This will help flight deck designers decide whether touchscreens are an appropriate technology for their intended use. It also quantifies the impact of target size, which can be used to develop guidelines for minimum touchscreen target sizes for the flight deck environment. Lastly, it helps inform about the utility of using a simple hand support under vibration.
