FAA Office of Aerospace Medicine
Civil Aerospace Medical Institute

Report No: DOT/FAA/AM-15/16

Title and Subtitle: The Influence of Looping Next-Generation Radar on General Aviation Pilots' Flight Into Adverse Weather

Report Date: August 2015

Authors: Knecht WR, Frazier E

Abstract: Looping Next-Generation Radar (NEXRAD) is currently finding its way into general aviation aircraft cockpits. Pilots may use this to try to pick their way through convective weather cells, with fatal results. This suggests a need to understand how well can pilots maintain safe clearance from severe weather when using this type of technology.

A looping NEXRAD-type cockpit display was created as a part-task simulation. NEXRAD-type images of various types of simulated adverse convective weather were created using a mathematical model of weather to precisely control the placement and movement of weather cells, and to measure the effect of the opening and closing of gaps, as well as weather system depth.

Results indicated that weather system depth made no difference for the values tested. In contrast, moving weather appeared to greatly decrease pilots' ability to judge how closely their planned flightpath would approach hazardous weather (measured as point-of-closest-approach, PCA). Moreover, it did not seem to matter if weather movement was relatively fast or slow, nor whether gaps were opening or closing. The results indicate judgment of PCA with any movement of weather was clearly difficult.

This has considerable implications for in-cockpit use of looping NEXRAD. First, it is not anticipated that first-generation looping NEXRAD will be adequate for safe penetration of gaps between storm systems. Second, while training could be expected to improve performance, training alone may not be sufficient. The display concept itself may require considerable human factors modification and testing to overcome multiple safety issues, not only those revealed in this study but also known additional issues of data latency, weather-movement prediction, and the inherently more unpredictable nature of natural weather itself.

The results suggest that in-cockpit NEXRAD could benefit from a) a zoom feature to allow a bigger picture of the weather hazards, b) a range ring to show how far the aircraft could travel in 1/2 hour, c) a method of projecting how far hazardous weather might be expected to travel in 1/2 hour, and d) a planning feature to estimate PCA of intended flightpath to hazardous weather.

Key Words: Aviation Weather, NEXRAD, Weather Flight, Weather in the Cockpit, Weather Avoidance, Convective Weather

No. of Pages: 47