Effects of latency on flight information displays

Abstract

New display architectures will be required to efficiently handle video and graphics from a wide variety of sources with minimal latency in order to minimize operator error and reduce the likelihood that pilot-induced oscillations (PIO) will occur. These new display systems must be able to handle up to sixteen video and graphics sources, including forward-looking infrared (FLIR) and weather information. We designed a pilot-in-the-loop flight simulator study to determine the effects of latency for a head-down Primary Flight Display (PFD) with a large field of view Synthetic Vision surround, a central inset containing sensor imagery (Forward Looking Infrared), and a non latent 2D guidance symbology layer. The investigation was designed in two parts, a breadth study that served as an overall screening for the effectiveness of a relatively large number of variables, and a depth study that explored deeper into effects caused by variables that were deemed significant and important from the breadth study. The results of our study indicate the need to synchronize the latencies of a large field of view attitude indicator and a central inset FLIR overlay. Unsynchronized overlays cause an effect that we refer to as "swimming", which is annoying to the pilot, leads to higher workload, and causes distractions that may lead to some amount of flight technical deterioration as demonstrated by our results. Within the limits of the latencies that were administered in this study, we found only a very small effect on actual flight technical performance. Positional accuracy and heading alignment was not strongly affected and generally remained well within limits specified by most practical test standards (PTS). Pilots tended to compensate by operating the flight controls with more gain and with larger amplitudes. This change of the controlling strategy indicates a reduction in aircraft controllability and may not be desirable for prolonged operations.