As you may know, the FAA is working on Runway Status Lights (RWSL). It’s a new system that’s live at 20 airports in the US. Basically, you get a nice set of red lights (embedded in the ramp) that tell you whether it’s safe or not to proceed. These lights are installed (or placed or located) at the entrance of the runway and at the start of takeoff. If any of these lights are red, you don’t go. Simple as that.

Diagram of RWSL

These lights are fully automated and completely independent of ATC, which means they do not have a clue if the lights are red or not. This is intentional. If you get clearance from ATC, and you see red lights, the red lights take precedence over the controller. The FAA has issued SAFO17011, stating:

There have been several instances at RWSL airports where flightcrews have ignored the illuminated red in-pavement RWSL lights when issued a clearance by Air Traffic Control (ATC). Illuminated RWSLs mean aircraft/vehicles stop or remain stopped and contact ATC for further direction, relaying to ATC that the RWSLs are illuminated.

This system will be expanding throughout the United States, and you can read more about the system here: FAA Runway Status Lights.