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To “B,” or Not to “B” ...

Why Equipping with ADS-B Makes Sense, Even in Places It’s Not Required

By Tom Hoffmann
Source: FAA Safety Briefing, July/August 2020

At precisely 12:01 am (0001Z) on January 02, 2020, the FAA’s mandate for Automatic Dependent Surveillance-Broadcast (ADS-B) Out took effect, requiring most National Airspace System (NAS) users in designated rule airspace to be equipped with this next generation surveillance technology. No, no airplanes dropped out of the sky, nor did radar screens across the country go black. Instead, thousands of pilots quietly went about the business of flying, but with an entirely new system of situational awareness and safety working in their favor.

This historic milestone capped off over a decade of hard work and coordination among regulators, manufacturers, educators, and industry stakeholders. That’s not to mention the thousands of pilots who, since the requirements were first laid out in 2009, have weighed the pros and cons of different ADS-B options and worked diligently with repair stations to have these systems properly installed in time.

As the FAA initially communicated during the ADS-B launch, equipage was not an across-the-board requirement. The FAA carefully weighed the cost-benefit of installation and decided that ADS-B Out would be mandated only for those aircraft that operate in or transit through “rule air-space,” essentially anywhere a transponder is required. For pilots who operate in or around major cities or metropolitan areas, equipping was a given. However, for those who fly in some of the more rural swaths of the country, it was a more calculated decision. Would the expense of equipage and inconvenience of aircraft down time be worthwhile? That’s a question many faced, and perhaps still face today. Allow me to share some information that might help inform your decision and explain why ADS-B matters, even when it’s not required.

The Art of B’ing

Let’s start with a quick refresher. ADS-B is a foundational NextGen technology that uses GPS to track aircraft in real time and improve situational awareness. There are both Out and In components that serve distinctly different purposes.

With the now-required ADS-B Out system, Air Traffic Control (ATC) can get an exact latitude-longitude position for an aircraft about every second. It also allows ATC to see and provide services to aircraft near mountains and rough terrain, over bodies of water, and at lower altitudes where line-of-sight radar struggles.

ADS-B In systems give appropriately equipped aircraft the ability to receive traffic and weather information in a variety of display formats (panel mounted, portable tablet). These services, known as Traffic Information Services-Broadcast (TIS-B) and Flight Information Services-Broadcast (FIS-B), offer pilots critical surveillance information on surrounding traffic as well as a host of weather and aeronautical information products.

Under the mandate, ADS-B Out is required to operate in most controlled airspace in the United States. If you fly where a transponder is required, you need ADS-B Out. However, there’s still a lot of aerial real estate where that doesn’t apply. For example, in Alaska, where all airspace below 18,000 feet (outside the Class C at Ted Stevens Anchorage International Airport) remains outside rule airspace. It’s natural to see how some might be opposed to equipping with ADS-B Out, especially when an operator may only sporadically need to access ADS-B Out rule airspace.

According to FAA Contractor and Leidos Senior Systems Engineer Jim Wright, there’s still tremendous value in having just an ADS-B Out solution. “ADS-B Out allows other aircraft who have ADS-B In to see and avoid you, significantly reducing the risk of mid-air collisions,” says Wright. With ADS-B Out, your aircraft creates a “hockey puck” shaped zone of about 30 miles in diameter around your aircraft (with a 3,500-foot buffer above and below) that allows other ADS-B Out/In equipped aircraft in that vicinity to pick up your location.

Also, due to the significantly better coverage with ADS-B, having an aircraft equipped with ADS-B Out increases the likelihood of a successful search and rescue mission. In places like Alaska where radar coverage is minimal, this feature is significantly more relevant. Just ask Wright, who would have benefitted greatly with having the position accuracy and speedier recovery action of ADS-B after a tragic accident in Alaska in 1994. Caught in a blinding snowstorm, Wright’s Cessna 206 crashed on a beach and hurtled into a grove of spruce trees. Rescuers lost precious time searching for the crash site along a 25 mile route based on Wright’s last known position. With ADS-B Out data, the crash site could have been narrowed to a 1,000-foot perimeter. “Even if the aircraft operates outside a coverage area,” he continues, “the route can be tracked to the point where coverage is lost.” Wright wound up losing part of his leg after that accident, but he lives to tell the tale of how ADS-B is a true life-saver.

ADS-B Alaska map

It’s the “In” Thing

The benefits of ADS-B Out alone are a strong incentive to equip, but where those benefits go to the “next level” is with adding ADS-B In. Equipping with both gives pilots the full package of situational awareness with traffic and weather information at a relatively modest price point. Since it’s not required, pilots also have more flexibility in adopting an ADS-B In solution, including the popular and cost-effective BYOD (bring your own device) option. There are now 19 FIS-B products available with more on the way. Some of the more recent products include cloud top reports, icing forecasts, and turbulence information.

The FAA is also working on a plan to beef up the FIS-B reception range in Alaska to help pilots pick up information on developing weather further out. “Boosting signal power will allow you to maximize your situational awareness and plan for conditions that you see forming before you find yourself in trouble,” says FAA’s Alaska ADS-B Expansion Lead Jamal Wilson. The project is still in the beginning stages, but Wilson is optimistic with it moving forward very soon.

An important side note here: FIS-B and TIS-B information is strictly advisory in nature and should never be used in place of see-and-avoid practices.

See and “B” Seen

Having both ADS-B Out and In has another distinct advantage, especially in areas like Alaska where ADS-B ground station coverage is limited or lacking. Aircraft that have ADS-B Out (either a 1090 ES or 978 MHz unit) and a dual band ADS-B In receiver, can “talk” to each other and swap position information without the need of a ground station. When within range of a ground station, ADS-B In/Out equipped aircraft have a more complete traffic picture and can even detect other non-ADS-B targets that have a transponder.

Alaska currently has 42 ground stations covering some of the more highly trafficked areas, but there are gaps the FAA is working to address. According to Wilson, the FAA is taking a phased approach at improving ADS-B coverage in Alaska, aiming to add ground station infrastructure at 12 locations in the near future. “These additional ground stations could go a long way toward filling out the coverage in the center of the state, and between Anchorage and Yakutat which includes Cordova,” adds Wright. The expansion efforts respond to requests from aviation stakeholder groups and reinforce action on some of the key takeaways from the NTSB’s 2019 roundtable discussion on part 135 operations in Alaska. See the NTSB Chairman’s blog post on the subject here:

But Maybe I Don’t Want to “B” Seen

Privacy is a concern with some operators who may have issues with their real-time position and information being made public. The FAA has implemented the Privacy ICAO Address (PIA) program to address these concerns. PIA enables interested and eligible aircraft owners to request an alternate, temporary ICAO address, which will not be assigned to the owner in the Civil Aviation Registry. The program will be implemented in two phases, with the FAA maintaining initial control. A second phase will transition PIA control to a third party service provider. For more on PIA and how to submit a request, see Aircraft owners concerned with privacy should also look into the anonymous mode available on a majority of UAT/978MHz ADS-B systems.

“B” Part of the Solution

The reasons and rationales for equipping with ADS-B are numerous. But none can be more compelling than its potential to save lives. A recent FAA safety analysis concluded that Alaska air taxis with ADS-B In experienced an overall accident rate that was 55-percent less than those unequipped. The same study also looked at the effect of ADS-B In on certain types of accidents in the lower 48 and noted a similar 50-percent average rate reduction for equipped aircraft, with a cut in the fatal accident rate of about 90-percent. These numbers, along with countless pilot testimonials on how it saves lives, speak volumes in support of a decision to equip with ADS-B, whether it’s required or not.

“The main challenge is getting people to equip,” says Jens Hennig, VP of Operations at the General Aviation Manufacturers Association. “Yes, you may only enter rule airspace once or twice in a state like Alaska, but having everybody on the same frequency will improve safety and operations. This is the future, not just a milestone. This is the surveillance technology we’re going to use for the 21st century.”


“Better with ADS-B — The Proof is In” — FAA Safety Briefing, July/Aug 2019 issue

Tom Hoffmann is the managing editor of FAA Safety Briefing. He is a commercial pilot and holds an A&P certificate.

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