Impact of Communication Delays on Pilot Workload and Performance in RPAS Landings: A Study of HUD Interfaces and Workload Metrics

Studies on managing critical failures during the flight of Remotely Piloted Aircraft Systems (RPAS) must be conducted, especially as long-distance operations between different cities become increasingly feasible. This study analyzes a simulated scenario in which, during a journey between cities, a critical failure occurs that does not affect flight dynamics but requires landing at an unmapped airport, without the ability to remotely adjust the landing settings. In this context, a pilot takes control of the aircraft and performs the landing at an airport along the route. Given that communication between the ground control station and the RPAS is conducted via satellite, a delay of approximately two seconds was observed between the pilot's command and the aircraft's execution. The experiment consisted of three flights, each utilizing a different Head-Up Display (HUD). During the flights, the Instantaneous Self Assessment (ISA) evaluation was applied, while the NASA-TLX was used after each flight to measure workload. After the three flights, the pilots completed the SWORD questionnaire to assess cumulative workload. The objective of this paper is to compare the different subjective evaluations (ISA, NASA-TLX, and SWORD) and investigate their correlation with the pilot's actual performance, aiming to understand the validity of these metrics in the context of RPAS operations under delay conditions.

Keywords: Remotely piloted aircraft systems, Pilot workload, Human performance, Instantaneous self-assessment, NASA-TLX, SWORD questionnaire, Human-machine interaction, Performance evaluation metrics.