The US government has expanded the use of an AI tool for advising air traffic controllers to assist in managing air traffic across the entire national airspace system. Airline executives have voiced support for the rollout, but the US labor union representing air traffic controllers has said it was not involved in designing or testing the AI-driven system.

The Federal Aviation Administration (FAA) says the $875 million SMART system has helped reroute 180 flights since being implemented in airspace over Washington, DC, on September 21. The agency claims that this saved an average of 10 minutes per flight and almost 80 gallons of fuel per flight—and it is apparently hoping such results can be replicated nationwide through the expanded deployment.

“After a successful initial rollout to the National Capital Region in September, the FAA will now use SMART in the airspace of all 22 centers across the country to reduce delays, reduce fuel consumption and improve the travel experience for the flying public,” according to the agency statement posted on November 10.

The FAA fact sheet describes SMART as a cloud-based system that combines information about “weather patterns, flight paths, traffic flow and controller staffing metrics” to predict air traffic patterns. It is designed to make scheduling recommendations, identify optimal flight routes, and determine the best order of arrivals for aircraft.

However, a human team of FAA specialists based in DC is ultimately responsible for validating the SMART system recommendations before passing them along to air traffic control facilities across the country, according to the agency.

Furthermore, the AI-powered SMART system “cannot be used to replace the critical role air traffic controllers play or take over control of an aircraft,” the FAA clarified in the September 21 announcement about the initial deployment. Local air traffic controllers can decide whether or not to accept the SMART system recommendations.

The previous FAA announcement included supportive statements from Delta Air Lines CEO Ed Bastian and American Airlines CEO Robert Isom.

But the National Air Traffic Controllers Association, which represents more than 15,000 members, also told Flying magazine that it was not consulted or involved in the “design, testing, or implementation of SMART and therefore cannot speak to its effect on the air traffic control workforce.”

Following the initial deployment in airspace above DC, the FAA expanded the SMART system’s coverage to air route traffic control centers in Atlanta along with Jacksonville and Miami in Florida, according to The Dallas Morning News.

The FAA also shared an example with The Dallas Morning News about how SMART recommended a shorter and faster route for a cargo flight arriving at Dallas-Fort Worth International Airport, although the newspaper noted that the agency did not identify the flight involved and has not provided information about how SMART may have assisted passenger flight traffic.

Ars has previously covered the SMART system’s development and lingering questions about how it works, as well as the air traffic controller shortage and other challenges facing the FAA.