Interaction between various terrain portrayals and guidance/tunnel symbology concepts for general aviation synthetic vision displays during a low en-route scenario

In support of the NASA Aviation Safety Program's Synthetic Vision Systems (SVS) Project, a series of piloted simulations were conducted to explore and quantify the relationship between candidate terrain portrayal concepts and guidance/tunnel symbology concepts, specific to General Aviation (GA). The experiments were conducted in a fixed based flight simulator equipped with two separate 6-inch Liquid Crystal Display (LCD) Head Down Displays, one serving as a glass cockpit style Primary Flight Display (PFD) and the other as a Navigation Display (ND). This work is the second part of a three-part study related to the Symbology Development for Head Down Displays (SD-HDD) test series. The focus of this experiment was on advanced low altitude en route maneuvers simulating a transition into Instrument Metrological Conditions (IMC) in the central mountains of Alaska (Merrill Pass). A total of 18 GA pilots, with three levels of pilot experience, evaluated a test matrix of four terrain portrayal concepts (TPC) and six guidance/tunnel symbology (GSC) concepts. Both quantitative and qualitative measures were recorded and analyzed. Quantitative measures included all pilot/aircraft performance data, flight technical errors (FTE), flight control inputs, and selected physiological data. The qualitative measures included pilot comments and pilot responses to the structured questionnaires such as perceived workload, subjective Situation Awareness (SA), pilot preferences, and the rare event recognition. Only a sample of the results of FTE, SA and workload is reported here. There were statistically significant effects found from GSC and TPC but no significant interactions between TPCs and GSCs for this experiment. Lower FTE and increased SA were achieved using SVS displays, as compared to the baseline Pitch/Roll Flight Director (PRFD) and Blue Sky Brown Ground (BSBG) combination. These results indicate that all pilots performed very well, mostly within the 75ft of vertical and lateral limits indicated by one dot of the course deviation indicators. With the same SVS training provided to all three groups, low time VFR pilots performed as well as IFR pilots in low altitude en-route scenario with IMC. Overall those GSCs that have both Guidance Cue and Tunnel performed better than the other concepts.