Now You See Me, Now You Don’t

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Authors: Ulf Ahlstrom
Joel Suss

Ahlstrom, U., & Suss, J. (2014). Now you see me, now you don’t: Change blindness in pilot perception of weather symbology (DOT/FAA/TC-14/16). Atlantic City International Airport, NJ: Federal Aviation Administration William J. Hughes Technical Center.


Objective: The overarching goal of this study is to perform a human factors assessment of the effects of variations in cockpit weather symbology on General Aviation (GA) pilot symbol perception.

Background: To support the Next Generation Air Transportation System (NextGen) program, ongoing efforts focus on the implementation and use of weather technologies and weather presentations.

Method: Sixty instrument-rated GA pilots volunteered to participate in the study. We manipulated the independent variable Weather Presentations by presenting weather information under three different symbology modes. In Experiment 1, we assess pilot perception of METAR symbols during flight and assess how this affects flight behavior, cognitive engagement, and decision-making. In Experiment 2, we focus on pilot perception of time-stamps and weather symbols in a “change-detection” experiment.

Results: The result shows that pilots (using different weather presentations) vary considerably in their overall perception of METAR symbol change during flight. The overall group detection ranges from a virtual blindness (25% detections) to a modest detection performance (62% detections). The result from the change-detection experiment shows that the detection accuracy varies greatly between different weather symbols and between different weather presentations. Although the average change-detection performance is high across all weather presentations for precipitation areas (on average, 89% to 94% correct detections), SIGMET areas (83% to 93%), and METAR symbols (83% to 91%), pilots are virtually blind to changes for lightning symbols (17% to 43%) and time-stamp information (13% to 20%). Conclusion: Weather presentation symbology affects pilots’ perception of symbol change and cognitive engagement. Pilot performance varies credibly between different symbology renderings of the same weather data.

Applications: This simulation is part of an ongoing assessment of the effects of weather-presentation symbology related to the optimization of weather presentations in cockpits.