Runway Status Light System (RWSL) is an automated system that warns pilots and surface vehicles if it is unsafe to cross or enter a runway via a series of red lights embedded in the pavement.
The Runway Status Light System is takes information from the airport’s ground surveillance radar, either Airport Movement Area Safety System (AMASS) or Airport Surface Detection Equipment-X (ASDE-X), detects the motion and velocity of the traffic on or approaching that same runway. When an unsafe condition for crossing exists, the system will activate the:
- Runway Entrance Lights (REL)
- Takeoff Hold Lights (THL)
- Final Approach Runway Occupancy Signal (FAROS)
The REL and THL are inpavement light fixtures that are directly visible to pilots and surface vehicle operators. FAROS activation is by means of flashing the Precision Approach Path Indicator (PAPI).
Runway Status Lights (RWSL) are an independent safety enhancement that enhances safety and does not substitute for an ATC clearance permission for movement or operation on the airport
The system Studies have shown that it will address about 65 percent of the high-hazard runway conflicts currently occurring at U.S. airports without adversely impacting runway capacity or controller workload.
Pilots approaching a runway will see red lights illuminate if there is traffic detected. Pilots & vehicles must stop when they see the red lights. Clearance to cross or enter a runway must be given by air traffic control. Once the lights go off the pilot must verify clearance before proceeding. RWSLs will also be used by vehicle operators.
Controllers can set in-pavement lights to one of five brightness levels to assure maximum visibility under a variety of conditions.
The system can be shutdown should RWSL operations impact the efficient movement of air traffic Shutdown of the FAROS subsystem will not extinguish PAPI lights or impact its glide path function. Whenever the system or a component is shutdown, a NOTAM must be issued, and the Automatic Terminal Information System (ATIS) must be updated.
Here’s a video showing the Runway Status Light System