Plane & Pilot
Tuesday, August 1, 2006

ADS-B: The FAA’s Bold New Bid To Change The Way We Fly

What’s this new technology we’re hearing so much about?

What’s this new technology we’re hearing so much about?

Aircraft owners usually cast a wary eye when the FAA introduces a new technology. With each announcement, owners are concerned about paying a price to retain their rights to use the country’s airspace, and there’s usually a mass grumbling that begins with “What’s in it for me?”

With ADS-B (Automatic Dependent Surveillance-Broadcast), the time hasn’t yet arrived when on-board equipment will be mandated, though based on what the FAA is saying and the funding decisions they’re making, it’s a reasonable assumption that the day is coming—not soon, but probably within the next ten years.

That’s the bad news about ADS-B. The good news, for those who want to equip their airplanes now, is that this technology, which provides pilots with datalink weather and traffic information sans a monthly fee, is already in place and fully functional for the East Coast, and it’s beginning its westward expansion.

By the end of 2005, more than 30 ground-based transmitters (GBTs) had been installed from New York to Florida, providing ADS-B coverage for an area that includes approximately 40% of America’s pilot population. Except for a few small gaps near Savannah and along the Florida coast south of Palm Beach, a pilot can now depart from the New York City area in an ADS-B equipped airplane, and fly to central Florida with free, real-time NEXRAD weather radar graphics and text displays of METARs and TAFs.

If that’s not enough to satisfy most users, the system also provides complete and full-time traffic displays that are derived not from the limited area info provided by transponders, but from a feed in the FAA’s main radar facility in Atlantic City (the images are uplinked and updated every few seconds). ADS-B aircraft also see other ADS-B aircraft as, second by second, they continuously broadcast detailed position information to each other (part of the “B” for “Broadcast” in ADS-B).

In the lower 48, ADS-B is an outgrowth of the Alaska-based Capstone Project, a program created to provide terrain clearance and traffic separation in non-radar-coverage areas (much of Alaska). That’s the “S” for “Surveillance” in ADS-B.

As the technology was being developed and then implemented, it became apparent to designers and engineers that, in addition to seeing where the plane was at all times, it was also possible to send information to the aircraft. Thus, pilots could get real-time weather and traffic information automatically (that’s the “A” for “Automatic” in ADS-B). It wasn’t long before a group within the FAA asked, if ADS-B worked so well in the harsh mountainous Alaskan terrain, wouldn’t it work just as well in the less-demanding lower 48?

Within the FAA, a department known as Safe Flight 21 was charged with encouraging individual states to install ADS-B ground stations. For some time, James McDaniel, the department’s Flight Safety Applications Manager, has been the government’s chief advocate for the new technology. McDaniel says, “I’ve been working on the program for about 10 years, from the early standards development and some of the early R&D work.

“Initially it was very slow. Ten years ago, it seemed like it would never happen. In the last two years we got a commitment from senior FAA executives to develop the initial East Coast application—that was a breath of fresh air and daylight into the program—and they said we can now show people what this technology can do for them. We developed that narrow corridor throughout the East Coast, and we called it the East Coast application. It has expanded beyond that, and we now call it ADS-B service delivery, and we’re delivering those services that ADS-B provides.”

One compelling reason for the FAA’s move to implement ADS-B is the high cost of maintaining ATC secondary radar systems. Last July, the FAA chose ADS-B as the “preferred option” for a future U.S. surveillance system, a commitment that will eventually involve the installation of an additional 420 GBTs throughout the country. As of January 2006, with the East Coast deployment and a few additional ground stations in Arizona, North Dakota, Ohio, and one at Oshkosh, Wis., there were units operating in 14 states, with nearly 20 more scheduled for installation.

Though the United States pioneered the FAA’s Capstone Project, it’s not alone in adopting ADS-B on a broad scale. Australia made the commitment to use the technology as its exclusive ATC surveillance method and is replacing its radar-based system with ADS-B. There are installations in Europe and Asia—China just decided to purchase several ground stations and transmitters for installation in 160 aircraft.

In the United States, currently only Garmin (with its GDL-90) supplies a Universal Access Transceiver (UAT) capable of providing the signals for viewing on its MX20 multi-function display. However, as the system’s software has been developed and paid for by the government, and since the software is available cost-free to any company with an interest in manufacturing its own transceivers and display units, economies of scale and the inevitable competition may soon significantly lower the high installation cost (approximately $9,000-$10,000).

Many companies are considering low-cost UATs whose signals can be displayed on existing handheld devices like portable GPS units and PDAs. If they’re successful in reducing the installation cost to a recently suggested total of less than $4,000 (including the portable display), and their services don’t require hefty monthly subscription fees, ADS-B will be an increasingly attractive option for pilots who want weather graphics, text products and traffic information in their cockpits.

  Real-World Flying With ADS-B  
  Sometimes you just get lucky. That was the case when I was approached in early 2005 by Steve Merritt of the North Carolina Division of Aviation. Merritt was calling to see if I was interested in taking part in a demonstration project to prove the effectiveness of ADS-B. North Carolina had recently invested more than $600,000 to install eight ground-based transmitters (GBTs) providing complete statewide coverage for this new technology, which not only offers radar-like coverage in areas with no radar, but also uplinks weather and traffic information to the cockpit. The only problem was that, at the time, the stations were broadcasting signals into a sky empty of aircraft equipped to receive the signals.

So, the state made the additional investment to equip 10 demonstration aircraft with ADS-B equipment; the catch was that the owners must already have a Garmin MX20 multi-function display (MFD) installed in their panels (the MX20 is currently the only MFD capable of displaying all ADS-B products). Several years ago, I’d installed an MX20 during a complete upgrade on the panel of my 56-year-old Ryan Navion, so I became a candidate to participate in the project.

In exchange for an owner’s willingness to give up several Saturday mornings over a three-year period to provide in-flight demonstrations of the technology to other N.C.-based pilots, the state would pay the complete cost for the installation of the required UAT and associated antennas.

Naturally, I jumped at the chance—my installation was the first of the 10 and was completed early in 2005. Beginning with a cross-country flight to Lakeland for Sun ’n Fun, a longer trip to Oshkosh, and numerous flights throughout Virginia, the Carolinas, Georgia and down the coast of Florida, what has become abundantly apparent is how many more trips I’ve been able to safely complete with on-board, real-time NEXRAD weather graphics, and METAR and TAF products. What has surprised me the most, however, is how much I’ve used the Traffic Information Services (TIS-B).

Frankly, I wanted ADS-B for the weather information, and thought the traffic would be an add-on frill. I couldn’t have been more wrong. Since ADS-B displays all traffic that ATC sees (everyone who’s squawking Mode C), and updates the display every second, the information is invaluable in locating potentially conflicting traffic. In fact, I now spot traffic well before ATC calls it for me, often eliminating the need for vectoring.

Soon (the FAA promises) ADS-B services will include the real-time display of temporary flight restrictions (TFRs). In the meantime, North Carolina has secured funding to equip an additional 10 aircraft with the technology. Hundreds of owners have taken part in the weekend demonstration rides (afterwards, almost all express their amazement at how useful the technology is), so filling those next 10 slots hasn’t been a problem.

ADS-B coverage is almost complete along the East Coast of the United States, and is fast-spreading westward. In fact, my only real complaint so far concerns the few times I’ve flown beyond the coverage area, a problem that’s steadily being eliminated as new ground transmitters are installed. It would have been hard to imagine just a few years ago, but my Navion now has no-fee, in-cockpit datalink weather and traffic information; not bad for a classic airplane well into its sixth decade of service.

For a look at sample ADS-B graphics, vist the FAA’s Safe Flight 21 Website at



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