Effect of weather state-change notifications on GA Pilot Behavior

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Authors: Ulf Ahlstrom
Robert Bastholm
Eamon Caddigan
Matthew Dworsky
Oliver Ohneiser
Kenneth Schulz

Ahlstrom, U., Caddigan, E., Schulz, K., Ohneiser, O., Bastholm, R., & Dworsky, M. (2015). The effect of weather state-change notifications on general aviation pilots’ behavior, cognitive engagement, and weather situation awareness (DOT/FAA/TC-15/64). Atlantic City International Airport, NJ: Federal Aviation Administration William J. Hughes Technical Center.


Objective: Results from the WTIC Phase 2 study showed that general aviation (GA) pilots performed poorly at detecting aviation routine weather report (METAR) symbol changes during flight (Ahlstrom & Suss, 2014)—attributed to the change-blindness phenomena. Here, we address this gap by examining the potential benefits of weather state-change notifications on pilots’ behavior and Weather Situation Awareness (WSA) during a simulated flight. A second objective of this study was to assess pilot sensitivity to weather symbology changes on Topological, Visual Flight Rules (VFR), and Instrument Flight Rules (IFR) aeronautical map backgrounds in a changedetection experiment. Method: Seventy-three GA pilots volunteered to participate in the study. During a simulated weather scenario, participants were randomly assigned to an experimental or a control group and flew a single-engine GA aircraft, initially under Visual Meteorological Conditions (VMC). The experimental group was equipped with a vibrating bracelet that notified participants of state-changes to displayed METAR, Special-Use Airspace (SUA), and Significant Meteorological Information (SIGMET) symbols. During the simulation, we recorded each participant’s horizontal and vertical flight profile, WSA, decision-making, cognitive engagement, weather presentation interaction, and distance from the aircraft to hazardous weather. Finally, we used a change-detection experiment to assess participant sensitivity to changes in weather symbols on three different backgrounds. Results: By assessing WSA, we found that the experimental group provided credibly more communications of weather information and maneuver/course change information and a higher number of “out-the-window” reports to the pilot following than the control group provided. This supports our hypothesis that weather state-change notifications result in earlier and more accurate recognition of weather state-changes and, thereby, positively improves participant WSA. The results of distance-to-weather analyses showed that both groups kept similar distances to 30 dBZ precipitation cells. It also showed, however, that participants in both groups flew closer to hazardous weather than what is recommended in current guidelines. Although not a credible difference, there were more participant reports of VFR flights into Instrument Meteorological Conditions (IMC) in the control group (N = 33) than in the experimental group (N = 27). When analyzing the functional near-infrared (fNIR) data, we found credibly higher prefrontal oxygenation levels in the control group compared to the experimental group. We attribute the reduced cognitive load in the experimental group to increased participant WSA. Because of the state-change notifications, participants were more attentive to information on the weather presentation, which enhanced planning and decision-making and reduced cognitive load. Finally, participant discrimination performance for symbol changes was low on the Topological, IFR, and VFR map backgrounds when compared to the performance of a simulated group of ideal observers. We interpret these findings to indicate that much work is still needed to optimize the symbology for cockpit weather presentations to achieve good symbol discrimination and reduce the time needed to differentiate weather presentation elements on all backgrounds. Conclusion: Weather state-change notifications improved WSA and reduced cognitive workload. However, these improvements did not translate to changes in participants’ weather-avoiding behavior, indicating gaps in pilot understanding of the information or gaps in pilot decision making. 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.