The Crosscheck: Tools To Prevent Runway Incursions

I have written previously that improvements to tools, staffing and work environments would help mitigate runway incursions. I suggested the FAA require anti-blocking circuits in ATC and aircraft radios to prevent some runway incursions. That would lessen one of the risks that cause incursions, but there are other risks as well. Sometimes two airplanes or an airplane and a vehicle wind up at almost the same spot on a runway even when their radio transmissions are clear. That requires some different tools.

One of the tools the FAA has developed to mitigate the risk is the Runway Status Light (RWSL) system. The lights work pretty well but do they work well enough?

RWSL systems consist of two types of lights—Runway Entrance Lights (REL) and Takeoff Hold Lights (THL). They function automatically and are independent of air traffic control. RELs are installed in the pavement where taxiways intersect with runways, and they illuminate in red to indicate to a taxiing pilot that an airplane is approaching or the runway is occupied by another airplane. THLs are installed along runway centerlines, and they illuminate in red to indicate to a pilot about to take off that another airplane or a vehicle has encroached on the runway.

The system has had some success. The FAA in 2019 said “the effectiveness of RWSL at the 15 airports where it was operational in 2017 found an overall 52% reduction in the average runway incursion rate, with 15,484 potential saves by the technology.” What the agency  didn’t say was there had also been a few incursions despite the presence of RWSL.

On Jan. 29, 2016, an Airbus A321 crew operating a late-night flight from Fort Lauderdale/Hollywood International Airport (FLL) in Florida commenced the takeoff roll despite the fact that the THLs were illuminated. The tower controller caught her own mistake in issuing them takeoff clearance in time to stop the takeoff when controllers’ ASDE-X (Airport Surface Detection System, Model X) surveillance system alerted. The captain claimed he never saw the truck on the runway and recalled that the THL lights went out as they accelerated. He didn’t know that was feature of the system.

On Dec. 14, 2016, a Canadair CL-600 regional jet crossed the runway hold short line to Runway 28L at San Francisco International Airport (SFO) at the taxiway Juliet (J) intersection while another air carrier flight was on takeoff roll. Taxiway J was not equipped with RELs since it was a high-speed taxiway and was only intended to be used as an exit. Even though an RWSL system was installed at the airport, it didn’t prevent the incursion.

More notable incursions took place at RWSL- equipped airports in 2023. On Jan. 13, an American Airlines Boeing 777-200 crossed Runway 4L without ATC clearance at John F. Kennedy International Airport (JFK) in New York. A Delta Air Lines Boeing 737-900ER was forced to abort its takeoff as a result of the incursion. The FAA’s RWSL diagram of JFK shows there is an REL at the “J” taxiway by Runway 4L, the point where the American flight crossed that runway. It should have prevented the incursion.

A Learjet 60 took off without clearance from Runway 9 at Logan International Airport (BOS) in Boston on February 27 and almost struck a JetBlue E190 that was about to land on Runway 4R. According to the FAA Mandatory Occurrence Report filed for the event, the “Runway 9 status lights displayed red.” Were the lights bright enough? Was the warning timely? We don’t know.

On August 11, a Cessna Citation 560XL overflew a Southwest Airlines Boeing 737 at San Diego International Airport (SAN), resulting in a loss of separation. SAN’s Runway 9/27 is equipped with RELs, but the preliminary report at this writing did not say if they were a factor in the incident.

So far, neither the completed nor the preliminary NTSB reports on these incidents have suggested any design flaw in the RWSL system, but it seems to be a question worth asking. RWSL systems are now deployed at 20 major U.S. airports and if there are improvements needed, now is a good time to find out.

On Oct. 13, the FAA informed the NTSB that it would spend more than $100 million to reduce runway incursions at 12 airports. The projects include changing confusing taxiways, adding lighting systems, and providing flexibility on the airfield. No new RWSL installations were mentioned.

Following several serious incidents in late 2022, the FAA named a six-member Safety Review Team to examine safety and reliability in the nation’s air traffic management system in April. In a final report released on Nov. 15, the independent team recommended that training more controllers is the biggest near-term step the FAA can make to improve system safety and efficiency. The report makes 24 recommendations overall.

FAA ‘Sprint Efforts’
As one of the tools to prevent incursions, however, RWSL may have reached the point of diminishing returns.

A hint of the direction the FAA seems to be going is in its most recent reply to NTSB Recommendation A-00-066. That recommendation proposed a ground movement safety system that would provide direct warnings to flight crews. The FAA says it will make a “sprint effort” toward a Surface Awareness Initiative to provide surface traffic displays at airport towers that do not currently have a surface surveillance system. This sounds like an attempt to find a less costly way than RWSL systems to prevent incursions at second and third level airports.

Other “sprint efforts” are being devoted to an Approach Runway Verification (ARV) system to aid controllers in checking aircraft runway alignments and a new Runway Incursion Device (RID) memory aid for controllers.

A measure of the persistence of the runway incursion threat is the age of the NTSB recommendation. It was issued in 2000 and replaced a similar recommendation issued in 1991. If you are less than 32 years old, this effort to stop runway incursions is older than you are.

It appears that the FAA is making an all-out effort to improve the tools we need to operate our complex air traffic management system without having any more runway incursions. Let’s hope the effort pays off.