AOPA pushing ADS-B privacy forward

ADS-B uses GPS satellites to determine an aircraft’s position, and then transmits it to FAA ground stations and other aircraft; it is a key technology behind the agency’s Next Generation Air Transportation System and the FAA has mandated ADS-B Out for flight after Jan. 1, 2020, primarily in airspace where a transponder is required today.

“AOPA understands privacy has become a leading concern for many general aviation pilots deciding whether to equip with ADS-B and, should they decide to equip, which system to install,” said Rune Duke, AOPA senior director of airspace, air traffic, and aviation security. The technology also allows third parties to track ADS-B Out-equipped aircraft, including those squawking a 1200 VFR transponder code, and display aircraft identification to the public in real-time. 

These privately operated networks bypass the FAA’s established Block Aircraft Registration Request (BARR) program and Aircraft Situation Display to Industry (ASDI) data—and charge operators who wish to remove their aircraft from display to the public. 

Aircraft operators who choose to equip with a 978-MHz Universal Access Transceiver (978UAT) for ADS-B Out can, if their hardware supports it, select what’s called anonymous mode during certain operations. Under the rules, the aircraft must transmit its registration number or the call sign filed on the flight plan “except when the pilot has not filed a flight plan, has not requested ATC services, and is using [an approved 978UAT transmitting a self-assigned temporary ICAO code].” 

An aircraft receiving ATC services must squawk a discrete transponder code, which normally disables the anonymous mode. However, an aircraft that has filed a flight plan—even if it is squawking 1200 and not receiving radar services—cannot, under the rules, utilize the 978UAT anonymous mode. AOPA has heard from numerous pilots that this limitation on filing a VFR flight plan is onerous and discourages them from equipping with ADS-B, or from filing a VFR flight plan. 

So, AOPA has petitioned the FAA—the first step in changing the rules to allow anonymous mode when a pilot has filed a VFR flight plan, has not requested ATC services, and is operating outside 14 CFR 91.225 rule airspace.

“It is clear that privacy or anonymity must now originate at the aircraft and not from an FAA system downstream,” Duke wrote in the FAA petition. “The UAT ADS-B system with anonymous mode is the only approved method of achieving ADS-B regulatory compliance and an equivalent level of privacy as is available for solely Mode C transponder-equipped aircraft.”

Next, the petition will be published in the Federal Register and, following a comment period, AOPA anticipates that the exemption will be granted. As part of this process, the FAA will need to identify the limitations or requirements, if any, that will be imposed on pilots who choose to operate under any approved exemption.

What about 1090ES?

The anonymous mode offered by 978UAT is not an option for all operators, Duke noted—especially for turbine-powered and other aircraft operating above Flight Level 180 or internationally, where a 1090-MHz Extended Squitter (1090ES) transponder is required for ADS-B Out compliance.

And relief for some 1090ES operators is slowly moving closer, Duke said. Earlier this year the FAA sought feedback on the idea of “rolling ICAO codes,” which could provide anonymity for aircraft equipped with 1090ES ADS-B Out hardware.

In an early December presentation, the FAA’s Surveillance and Broadcast Services program office gave an update on what it’s now calling Private ICAO Addresses (PIA). The office has addressed concerns surrounding privacy and data collection, and determined that PIA would not introduce any new hazards to the National Airspace System. The FAA will contract with one or more third-party service providers for a technology demonstration in early 2019, Duke said.

Melissa Rudinger, AOPA vice president for government affairs, wrote the FAA on the subject in April 2018.

“The concept of ‘rolling ICAO codes’ is a promising approach to increasing anonymity for general aviation operators. Rolling ICAO codes refers to the idea of the aircraft emitting randomly assigned ICAO codes that will be changed periodically. In combination with an anonymous call sign, the aircraft would be harder to track,” she wrote. “This is a feasible solution and we look forward to other suggested approaches from vendors as to how to improve real-time privacy of aircraft using ADS-B and Mode S transponders.”

It is important the FAA collaborate with Nav Canada to determine a privacy solution that would be compatible with Canadian airspace, she noted. “The solution must not be onerous for owner-operators to the point that it limits participation, [and] privacy should be available whether or not the pilot is utilizing air traffic services. The FAA should continue working with industry to find a long-term solution to encrypting Mode S and ADS-B messages to ensure privacy is being provided automatically at the source, Rudinger added.