Runway status lights

A captain I was flying with once made this sarcastic observation while we were taxiing to the departure end of the runway. The sun was going down, and the flashing lights in question were in place to mark a part of the taxiway that was being repaired. It was the first day this project had been added to the NOTAMs, and a note to the pilot group had been disseminated several days earlier. We had discussed it in our pre-departure taxi brief, and his comment was a subtle dig that airports always seem to have lights on for something.

Some years ago, the FAA began using what they call Runway Status Lights, shortened to RWSL. RWSL were introduced to cut down on the number of runway incursions by aircraft and ground vehicles. Initially deployed at Dallas Fort Worth (DFW), RWSL systems are now present at approximately 20 of the busiest/most-prone-to-incursion airports in the country. The lights are automatically operated on the runway or taxiway where traffic may commonly hold short while waiting to enter or cross a runway.

The system requires no input from air traffic control (ATC) personnel. In fact, if a controller gives you a clearance that is contrary to the red lights of the RWSL, you are required to honor the lights and query the controller. However, I’ve never personally seen this happen.

If you’re new to the airlines and/or corporate world where operations to such airports are common, there is a good chance you will see the RWSL in the simulator. If it is available, ask your sim instructor to do both a day and a night demo. Without getting into all the various modes and triggers, the two most common things you will see will be red lights in the pavement that warn you to not enter a runway due to a departing or arriving aircraft, and another set of in-pavement lights in the takeoff zone to warn you not to start a takeoff roll due to crossing traffic or an incursion down the runway.

There are some great documents, training materials, and videos on the FAA website for RWSL, along with a map of currently operational systems. There are also some good diagrams available for viewing of airports that have RWSL installed. Boston, for example, has a very congested layout of runways, and RWSL makes ground operations—especially in low visibility common to coastal areas—much safer.

Unfortunately, it is unlikely that RWSL will spread to more than a limited number of airports due to the cost of installation and upkeep, but that is always something that might change. In the meantime, where airports have it, pilots need to be aware of the system and what it means when encountered. After all, RWSL just might save your life.