Lighted X Runway Closure Marker—Flight Testing

On July 7, 2017, an Airbus A320 nearly collided with another aircraft on Taxiway C at San Francisco International Airport. The A320 mistakenly aligned with the taxiway instead of the parallel runway on which they were cleared to land. Because of this incident, the National Transportation Safety Board (NTSB) made a safety recommendation to improve the conspicuity of closed runways, particularly under nighttime conditions when at least one parallel runway remains in use. The Federal Aviation Administration (FAA) Office of Airports tasked the National Institute of Standards and Technology (NIST) to evaluate different configurations of Lighted X (LX) systems. NIST’s laboratory experiments with pilot participants revealed that larger 28-foot LX configurations were more recognizable from greater distances. However, the findings needed validation through real-world flight testing in varied lighting conditions to confirm their practical applicability. The FAA Airport Technology Research and Development (ATR) Branch conducted research to test and evaluate LX runway closure markers (RCMs) in real-world scenarios to validate NIST’s laboratory results. Eighty-eight test configurations were considered to evaluate the optimal intensity, size, and flash rate of the RCMs. Given this large test set and the costs associated with conducting flight testing, ATR conducted a two-phase test approach: ground tests at the Lakehurst Naval Air Warfare Center Aircraft Division (NAWCAD) and flight tests at Cape May Airport (WWD). Results from ground observations were used to eliminate RCM configurations that pilots found least viable, leading to a reduction from 88 test configurations to 33 based on pilot feedback. This report focuses on the results gathered from Phase 2 and provides a comprehensive summary of flight testing and recommends optimal LX configurations for intensity, size, and flash rate to better signal runway closures to pilots during operations.