Despite airspace users’ slow progress toward meeting the 2020 ADS-B Out equipage mandate, the FAA is already considering which mix of radars will be retained to serve as a backup to the new ATC surveillance paradigm. The agency plans to provide the backup through a layered system of transponder-based and primary radars, said a senior FAA executive.
“People may have heard that the ADS-B program was a ‘radar-replacement program.’ That’s not the case—we have identified backup requirements,” said Robert Nichols, FAA surveillance services group manager. The challenge of transitioning to ADS-B surveillance in January 2020 will be choosing which legacy radars to retire and convincing controllers that the ATC system is “as good and as safe as it was before,” he told the Air Traffic Control Association (ATCA) annual conference on October 16.
The FAA will run the layered backup system through a Safety Management System process to mitigate risk, Nichols said. The system will incorporate existing “cooperative” surveillance methods that interact with aircraft transponders, including Mode S, multilateration ground stations and ATCBI (air traffic control beacon interrogator) 5 and 6 secondary surveillance radars. The FAA will no longer provide a Mode S traffic information service (TIS), which is replaced by ADS-B In's TIS-B feed.
The agency is rethinking the deployment of primary “skin-paint” radars that detect both transponding and non-transponding aircraft targets by reflected radio signals, taking into account the needs of the Department of Defense (DOD), Nichols said.
“Is there a stated need for the FAA to have skin-paint radar? We need it in the low altitude for sure, but how do we right-size that?” he asked. “That’s when you have a stray, unequipped guy roll into a potentially high-density airspace. In the upper altitude, currently we don’t have a stated need for it, although DOD does. Really, the strategy that we need to look at here as we go forward is where and what do we need in all the airspace?
“The radar removal is going to be difficult,” Nichols acknowledged. “I’ll be retired by the time we take the first one out, probably. I’ve got about a year.”
The ADS-B system calls for aircraft to regularly broadcast their GPS-derived position to a network of ground stations, from where the information is piped to ATC centers. The transition from a ground-based radar paradigm assumes widespread compliance by airspace users with the FAA’s ADS-B Out equipage mandate. With a little over two years left to equip, just 43,344—or 27 percent—of all U.S. aircraft have been fitted with the necessary avionics of the 160,000 the FAA estimates will need to be equipped across the general aviation, military and air carrier segments, according to the agency’s latest available numbers. Of those, 6,177 are “nonperforming emitters” that failed to meet the FAA’s performance standard because the avionics were installed incorrectly.
As of May, U.S. carriers had equipped 1,367 of roughly 7,000 overall airliners, led by United Airlines with 242 and UPS with 232, according to the FAA. Responding to a petition by trade group Airlines for America on behalf of its member carriers, the FAA in August 2015 issued Exemption 12555, which allows airlines to operate through 2024 using GPS receivers that do not meet required navigation accuracy and integrity performance standards. But they still must install ADS-B Out transponders by the 2020 deadline.
Also speaking at the ATCA conference, Joe Bertapelle, JetBlue Airways director of strategic airspace programs, described how the FAA is exerting pressure on airlines to equip for ADS-B through the industry-government NextGen Advisory Committee (NAC). At the October 4 NAC meeting at United Airlines headquarters in Chicago, Dan Elwell, FAA deputy administrator, called upon each airline executive in attendance to say whether they would make the 2020 deadline, “and they all said ‘yes, we’re going to make it,’” he related.
Through the industry-government “Equip 2020” initiative, the airlines have determined that the avionics supply chain has capacity and will be able to support their compliance with the ADS-B Out mandate. For Parts 121 and 135 air carriers, “there is a solution set for every airplane, and every CEO says we will make it, probably by mid-2019. We are building up to it. We’re in the transition now,” Bertapelle said.
Nichols agreed that the airlines “have plans” in place to make the FAA’s equipage deadline. “They were identified at the NAC a couple of weeks ago—that they were all on track,” he said. “But the metrics show you’re not on track; you’re well below the curve right now. It would be an upswing [to equip in time] and we are hearing that there’s going to be an upswing.”
Also lagging in equipping for ADS-B Out position reporting is the DOD, which oversees some 12,000 aircraft across the military services. At last count, there were 39 compliant systems installed, Nichols said.
The types of aircraft DOD is prioritizing for equipage are airlifters and tankers operated by the Air Mobility Command, VIP aircraft flown by the Special Air Mission based at Joint Base Andrews, Maryland, and aircraft used for command and control and intelligence, surveillance and reconnaissance, AIN has reported.
At the ATCA conference, Allan Storm, U.S. Air Force civil/military integration division deputy, explained that it is easier to fit the service’s 187 C-17 Globemaster III cargo jets for ADS-B Out than to equip fighters such as the F-35A, F-22 and F-16.
“I’m not going to make the mandate, and I’m not going to be close,” Storm stated flatly. “But the good news is…we are working on a memorandum with the FAA on how we’re going to accommodate both the equipped and the non-equipped.”