Supplementing haptic feedback through the visual display of flight envelope boundaries

Abstract

Haptic feedback on the side stick has been used in previous research on assisting pilots in recognising flight envelope limits. Pilots indicated, however, that it was not always clear what the haptics were trying to tell them, leading to a lower system acceptance. This paper describes the design and evaluation of a visual display in supplementing haptic feedback on the side stick as a way to communicate flight envelope boundaries to pilots. The design adds indications for the limits in airspeed, load factor, angle of attack and angle of bank to a standard Airbus primary flight display (PFD). The indications not only show the limits of the flight envelope, but also indicate the magnitude and direction of the cues given by the haptic feedback. Fifteen professional Airbus pilots and one Airbus sim instructor participated in an experiment in the SIMONA Research Simulator at Delft University of Technology. In the experiment several approaches in three different scenarios were flown with the old and new PFD while haptic feedback was always enabled. The objective results do not show a clear improvement with the new display, although the time spent outside the flight envelope is slightly reduced. Subjective results indicate a preference, however, for the new display as well as an increased understanding of the haptic feedback. Further research is recommended and should focus on improving the design by removing unused indications and setting up an experiment with a bank scenario that allows the use of the actual bank limits rather than artificially reduced limits.