Pilot
Category
N
VFR
IFR
Flight Director (P/RFD) or Unconnected Box Tunnel). Finally, on-pitch command, while the upper vertical limits were pilot’s technical performance will be improved with the tunnel removed from the Tunnel with Ghost Aircraft and Connected concepts without increasing pilot workload. Box Tunnel, thereby encouraging the pilot to gain altitude The experiment was conducted at NASA Langley while executing a missed approach.
Research Center (LaRC) using the SVS-GA General Aviation WorkStation (GAWS) fixed-base flight simulator. GAWS Mean Mean Pilot utilizes a Precision Flight Controls PC-based Aviation N Age Experience Category (yrs) (hrs) Training Device model PI-142 instrument trainer coupled with two 6-inch VGA monitors on the instrument panel and a VFR 9 43 293 SXGA overhead projector for the OTW depiction. For the IFR 6 35 766 SD-HDD experiment, the evaluation pilot (EP) flew the H-IFR 6 53 11,632 scenarios from the left seat and was required to utilize the Total 21 44 3,668 yoke, rudder pedals, and throttle quadrant, to operate the simulator. The primary elements of the GAWS instrument Table 1. Evaluation Pilot (EP) Data panel included the SVS-PFD and a navigation display (ND) with multi-level range selection capability, developed at The four TPC and four GSC combined to make a NASA LaRC. Pilot selectable fields of view (FOV) total of sixteen experimental display configurations examined (horizontal angle of the image that is presented on the display) for both the approach and missed-approach scenarios over the of 30 and 60 degrees were available throughout the scenarios course of a two-day within subject GAWS simulator for the PFD and the boundaries of the PFD FOV were experiment. Twenty-one subjects ranging in experience from depicted on the ND. Finally, the Initiative Computing low-time VFR pilots to high-time IFR pilots (Table 1) Electronic Instrument Training Environment (ELITE) flight participated in the SD-HDD experiment. The Juneau, Alaska, simulator software was configured with a Cessna C-172 terminal area (JNU) served as the simulation area of dynamic flight model.
operations for the two distinct scenarios. The approach This experiment, the initial simulation experiment of scenario required the subject pilot to fly downwind, base, and the SD-HDD series, focused on the approach and missed- short- final, flight segments to Runway 26, using a VMC-like approach modes of flight. In addition to the current basic PFD approach for each of the 16 SD-HDD display concepts.
background of Blue Sky over Brown Ground (BSBG), three Similarly, the missed-approach scenario required the subject Terrain Portrayal Concepts (TPC) were chosen (Figure 1) for pilot to fly short-final, straight-climb missed-approach, the SVS experimental terrain database. Constant Color with climbing right-turn crosswind, and downwind, flight segments Fish Net (CCFN), the lowest fidelity terrain concept, used a for Runway 8 at JNU, using each of the 16 SD-HDD display single color as the terrain texture and included a consistently concepts. For both scenarios, OTW visibility decreased from 9 spaced overlaying grid for the elevation cues of a digital nautical miles (nm) to 1 nm within one minute of the elevation model (DEM) with a resolution of 60 arc/sec. The beginning of each data collection run.
medium-fidelity terrain concept, Elevation Based Generic (EBG), utilized 12 graduated color bands to depict elevation RESULTS gradients within its 6 arc/sec DEM resolution database. Green was used to depict field elevation; the highest terrain within 50 The dependent variables for this SD-HDD nm was colored white; and uniform height color bands were experiment were both objective and subjective. For the used for elevations in between for the EBG concept. Photo objective data measures, a real-time data processor was used Realistic (PR), the highest fidelity terrain concept, used digital to score each data collection run immediately after data satellite photographs (4-meter imagery) overlaid on a 2 arc/sec collection for that run finished. A numerical score for each DEM resolution database. The Guidance Symbology run was calculated in terms of percent of time within the Concepts (GSC) chosen for the experiment were three tunnel Level-1 (L1) flight technical performance category based on concepts (Tunnel with Ghost Aircraft, Unconnected Box the combination of airspeed, vertical path, and lateral path, Tunnel, and Connected Box Tunnel) and one dual-cue flight error. The subjective data measures included a 3-D Situation director (Pitch/Roll Flight Director) (Figure 2). The dual-cue Awareness Rating Technique (SART), a standard NASA-TLX flight director served as the baseline for GSC for this (TLX) workload index, and specific questions about terrain experiment as this concept is used for current day PFD-type awareness and guidance awareness. At the end of each data displays. Each of the tunnel concepts were adopted from collection run the subject pilot was required to complete the various research organizations and industry applications and three-page subjective run questionnaire, administered digitally represent specific concepts in this area. Parameters that define on a Tablet PC. The run questionnaire provided the EP’s with each tunnel concept, such as size, shape, color, etc., were not the ability to convey instantaneous subjective estimates of SA modified from their nominal values for each tunnel concept.
(SART) and perceived workload (NASA-TLX) for each of the The tunnel concepts were also selected due to their relative 16 display concepts in both the approach and missed-approach clutter characteristics (from low to high). Furthermore, three scenarios, immediately after exposure to each particular of the four GSC automatically altered their attributes when the display concept. Both the objective and subjective data pilot executed a missed-approach. The pitch cue on the collected during the SD-HDD experiment were statistically Pitch/Roll Flight Director was modified to become a speed- analyzed using SPSS software.
Figure 1 – Terrain Portrayal Concepts (TPC) Figure 2. Guidance Symbology Concepts (GSC) Workload Situation Awareness A significant effect was found for GSC with respect A significant effect was found for GSC with respect to perceived workload (NASA-TLX), F (3,332) = 7.995 (p to SA, F (3,332) = 13.962 (p <.05), for the missed-approach <.05), for the missed-approach scenario (Figure 3a). The scenario. The tunnel with ghost aircraft GSC was found to tunnel with ghost aircraft GSC was found to produce produce significantly higher subjective SA then the other significantly less workload than the other concepts, for the concepts, for the missed-approach scenario. There were no missed-approach scenario. There were no significant significant differences for GSC with respect to subjective SA differences for GSC with respect to workload for the approach for the approach scenario. There was a significant effect scenario and TPC was not significant for either scenario. found for TPC with respect to SA for the approach scenario, Figure 3. Mean NASA TLX Scores There was a significant effect found for pilot category with respect to workload for the approach scenario, F (2,333) = 44.361 (p <.05) (Figure 3b), as well as for the missed- approach scenario, F (2,333) = 18.434 (p <.05) (Figure 3c). In both scenarios, high-time IFR (H-IFR) pilots were found to have the highest perceived workload. There were no significant differences found for either the approach or missed-approach scenarios for the interaction of TPC and GSC with respect to perceived workload.
Figure 4. Mean SART Scores F (2,332) = 8.156 (p <.05) (Figure 4a), as well as for the concept (TPC). The fourth and final hypothesis stated that missed-approach scenario, F (2,332) = 5.960 (p <.05) (Figure pilot technical performance would be improved with tunnel 4b). In both scenarios, the baseline PFD background of BSBG concepts. In terms of lateral and vertical flight technical error, was found to have the lowest subjective SA. There were no the Tunnel with Ghost Aircraft GSC produced the smallest significant differences found for either the approach or mean FTE, regardless of scenario or TPC. Furthermore, Photo missed-approach scenarios for the interaction of TPC and Realistic terrain, regardless of GSC, resulted in the highest GSC with respect to subjective SA. There was a significant mean subjective SA scores while having no negative impact effect found to exist for pilot category with respect to on FTE, for both the approach and missed-approach scenarios.
subjective SA (SART) for the approach scenario, F (2,333) = Interestingly, pilot category had a significant impact 27.666 (p <.05) (Figure 4c), and for the missed-approach on perceived workload, SA, and L1 performance, for the scenario, F (2,333) = 16.203 (p <.05) (Figure 4d). In both missed-approach scenario and on perceived workload and SA scenarios, high-time IFR (H-IFR) pilots were found to have for the approach scenario. During the approach scenario, VFR the lowest subjective SA. pilots who were unfamiliar with IMC flight were able to do as well as highly trained IFR pilots in terms of controlling flight Level-1 Performance path error (no significant L1 differences), and with less workload and more situation awareness, as a result of SVS.
Immediately following each data collection run, a However, these results are troubling in that highly trained and numerical score for evaluation pilots were calculated in terms experienced pilots reported having higher workload and less of percent of time within the Level-1 (L1) flight technical SA without a significant improvement in L1 performance over performance category. L1 performance was analyzed for both their less experienced counter parts. This outcome may the approach and missed-approach scenarios however vertical simply be a result of dissimilar strategies employed by the path error was not a graded measure for the missed-approach different pilot categories when responding to the subjective scenario. An ANOVA performed on the L1 data found a SA and workload questionnaires or perhaps the intuitive significant effect for GSC on L1 performance for the approach nature of SVS truly does mitigate the perils that accompany scenario, F(3,320) = 24.842 (p <.01), as well as for the the loss of out-the-window visibility for VFR pilots. However missed-approach scenario, F(3,287) = 22.407 (p <.01). The more research needs to be performed before a conclusion can Tunnel with Ghost Aircraft GSC was found to be significantly be drawn in this regard.
better for achieving L1 performance for both scenarios. There were no significant differences found for TPC or the REMARKS interaction of TPC and GSC with respect to L1 performance for either the approach or missed-approach scenarios. This experiment was the first in a series of SD-HDD Furthermore, there were no significant differences found for experiments designed to investigate the interaction of terrain pilot category with respect to L1 performance for the approach and guidance concepts on a synthetic vision system primary scenario, however, pilot category did have a significant effect flight display (SVS-PFD). Future SD-HDD experiments will on L1 performance for the missed-approach scenario, F(2, focus on the enroute flight mode as well as the minification 287) = 3.9 (P<0.02). The H-IFR pilot group had a slightly effects over a range of field of view sizes on the SVS-PFD.
higher mean L1 performance then the other pilot groups for REFERENCES the missed-approach scenario.
Charlton, S. (2002). Questionnaire Techniques for Test and DISCUSSION Evaluation . In T.G. O’Brien & S.G. Charlton (Eds.), The first experiment hypothesis stated that providing Handbook of Human Factors Testing and Evaluation terrain on the PFD would improve pilot SA across all (pp. 225-246). Mahwah, NJ: Lawrence Erlbaum.
guidance symbology concepts. The results above indicate that Endsley, M. (1999). Situation Awareness in Aviation situation awareness (SA) was enhanced without negatively Systems . In D.J. Garland, J.A.Wise, and V.D. Hopkin impacting pilot workload or flight technical error (FTE) (Eds.), Handbook of Aviation Human Factors (pp.
during the approach and missed approach modes of flight, by 257-276). Mahwah, NJ: Lawrence Erlbaum.
providing a general aviation pilot with an integrated SVS display to use when OTW visibility is obscured. The second Glaab, L., and Hughes, M. (2003). Terrain Portrayal for nd and third hypotheses stated that low fidelity (simple) terrain Head-Down Displays Flight Test . 22 Annual concepts would favor complex guidance symbology Digital Avionics Systems Conference (DASC).
(Connected Box Tunnel or Tunnel with Ghost Aircraft) and Indianapolis, IN.
high fidelity terrain concepts would favor simple guidance Hughes, M. and Glaab, L. and. (2003). Terrain Portrayal for symbology (Pitch/Roll Flight Director or Unconnected Box Head-Down Displays Simulation Experiment Tunnel). Since there was no statistical evidence of an nd Results . 22 Annual Digital Avionics Systems interaction between TPC and GSC, the results of the data Conference (DASC). Indianapolis, IN.
analyses do not support these hypotheses. Perceived workload was lowest and subjective situation awareness was highest Hummel, K., Landsberg, B., Roy, K., & Wright, D. (2002).
with the Tunnel with Ghost Aircraft GSC, for both approach Nall Report 2002: AOPA Air Safety Foundation and missed-approach scenarios, regardless of terrain portrayal Accident Trends and Factors for 2001. AOPA Press.