The FAA’s Runway Status Lights (RWSL) system is now operational at all 20 major U.S. airports slated to have the new technology. According to the agency, this is the first system designed to automatically provide a direct warning to pilots and vehicle operators about potential runway conflicts.

The technology alerts pilots and vehicle operators to stop when runways and taxiways are not safe to enter, cross, or begin takeoff. Red lights embedded in the pavement illuminate when the presence of other traffic creates a potential conflict. RWSL uses the airport’s surface surveillance system to determine the location of aircraft and vehicles. The lights are fully automated, requiring no input from air traffic controllers.

Runway Entrance Lights (REL) are deployed at taxiway and runway crossings and illuminate if it is unsafe to enter or cross a runway. Takeoff Hold Lights (THL) are deployed in the runway by the departure hold zone and illuminate when there is an aircraft in position for departure and the runway is occupied by another aircraft or vehicle and is unsafe for takeoff.

A report on the effectiveness of RWSL at the 15 airports where it was operational in 2017 found an overall 52 percent reduction in the average runway incursion rate, with 15,484 potential saves by the technology.