Runway status lights

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The Runway Status Lights (RWSL) system is a technology the Federal Aviation Administration (FAA) is deploying to make runways even safer at busy airports. The system adds to the layers of protection already in place by providing visual alerts to pilots and drivers when runway traffic makes it unsafe to enter, cross, or begin takeoff. The lights enhance safety without affecting with normal and safe operations — an important consideration at airports that handle hundreds of operations an hour.

The system works by analyzing radar and satellite tracking data from Airport Surface Detection Equipment, Model X (ASDE-X) systems. ASDE-X systems use surface radar, multilateration, and in some cases ADS-B (Automatic Dependent Surveillance-Broadcast). The ASDE-X data includes location information for aircraft and vehicles. The RWSL system uses complex algorithms to calculate future paths and predict potential conflicts. The system automatically illuminates lines of bright red lights in the pavement of select runways when a potential conflict is likely to occur between two aircraft or vehicles. The RWSL arrays on taxiways light up any time an aircraft is landing or about to takeoff. The lights extinguish as soon as it is safe to move forward.

RWSL is important for ground vehicles as well as for aircraft, and work in exactly the same way. The lights help vehicle drivers avoid entering runways that are, or will soon be in use.

The system adds a vital layer of redundancy to runway safety and reinforces controller guidance without replacing it. Air Traffic Control (ATC) clearances are still required for any operation on airport runways.


Runway safety is a top priority at both the FAA and the National Transportation Safety Board (NTSB). Most runway incursions happen quickly, leaving little time for corrective action. Reducing these runway incursions is a critical safety effort. The goal is to enhance runway safety without affecting airport capacity.

The RWSL system helps reduce runway incursions by increasing the situational awareness of pilots and vehicle operators. The system automatically provides clear, prompt, and automatic alerts directly to pilots and drivers so no time is lost in transmitting warnings.

The lights supplement existing ATC tools and procedures without increasing controller workload. No input from controllers is required.


The RWSL system uses data from airport ground surveillance systems to detect traffic on or approaching the runways.

Two subsystems, the RWSL Processor and the Field Lighting System (FLS), work together to automatically illuminate and extinguish the in-pavement lights. The processor uses surveillance data to analyze real-time airport surface operations. The FLS provides the physical interface from the processor to the runway lights.

The system commands in-pavement lights to illuminate red when there is traffic on or nearing runways. On taxiways, Runway Entrance Lights (RELs) show that runways are not safe to enter or cross. On runways, Takeoff Hold Lights (THLs) show pilots that it is not yet safe to begin their takeoff. The system is fully automated and finely tuned for safety and efficiency.


The FAA plans to have RWSL operational at 17 airports in 2017:

The FAA will replace prototype RWSL systems with production systems at the following airports:

Further reading[edit]

  • Mouawad, Jad. “Safer Flights, But Risk Lurks on the Runway.” New York Times. New York Times, 24 Sept 2012. Web. 5 Oct. 2012.
  • Kaiser, Kimberly. “San Diego Int’l Switches to LED Runway Status Lights.” Airport Improvement Magazine. Chapel Road Communications, LLC, May 2012. Web. 5 Oct 2012.
  • Gersema, Emma. “Phoenix Sky Harbor, Other Airports Get Safety Upgrades.”, 26 May 2012. Web. 5 Oct 2012.
  • Turner, Aimee. “LAX Runway Status Lighting Advances.” Key Publishing Ltd Corporate, 9 May 2012. Web. 5 Oct 2012.
  • Aviation News Network. “Los Angeles, FAA To Advance Runway Lights Program.” Aviation News Today., 18 Apr 2012. Web. 5 Oct 2012.
  • Weikel, Dan. “More Runway Warning Lights Will Be Added at LAX to Increase Safety.” Los Angeles Times. Tribune Company. 16 Apr 2012. Web. 5 Oct 2012.
  • Namowitz, Dan. “Real-Time Runway Status Alerts Coming.” Aircraft Owners and Pilots Association Online. Aircraft Owners and Pilots Association. 28 Oct 2011. Web. 5 Oct 2012.
  • AeroSafety World Magazine. “Timing is Everything.” AeroSafety World Magazine. Flight Safety Foundation. Sept 2008. Web. 5 Oct 2012.
  • Levin, Alan. “Runway Safety Has Pilots Seeing Red.” USA Today. Garnett Co, Inc 24 Apr 2006. Web. 5 Oct 2012.