Equipping our airplanes with ADS-B is on our “radar” these days.  What does this new technology do for us? Is it worth it to equip? The FAA just provided a tool to anticipate where ADS-B coverage is available, which could help you decide whether to equip your aircraft.

Automatic Dependent Surveillance-Broadcast (ADS-B) was born in Alaska, as a demonstration project in the Bethel area — part of a safety program to reduce aircraft accidents.  It succeeded by significantly reducing the accident rate in southwest Alaska, along with the addition of more weather stations, instrument approaches, and other improvements.   This and follow-on projects contributed to the national system (NextGen) we are transitioning to today.  By 2020, pilots wishing to fly in certain classes of airspace will be required to have ADS-B Out, the component of the system that broadcasts your position once a second to other airplanes that are equipped to receive it.  And ADS-B Out also broadcasts to stations on the ground, which relay your position to Air Traffic Control facilities who may track you inflight, something that in the past only radar could do.  Of course, ADS-B also has an IN side. With additional additional equipment added to your airplane, you receive not only the location of OUT equipped aircraft, but weather information, pilot reports, NOTAMs and more.  However, to get the full benefits of the system, you need to be within the coverage footprint of a ground station to receive that data.  And that’s the rub. The network of ground stations in Alaska is pretty sparse.  The good news is that this month the FAA added Alaska coverage to the Google-Earth tool to see where you can expect to receive ADS-B coverage at different altitudes.  Below is an example.

The figure above shows that the ADS-B coverage at 3,000 feet above ground level is selected. Other choices in the file allow you to select altitudes from 500 feet to 10,000 feet agl. The file also contains ATC radar coverage which may be toggled on and off as well. Two routes between Anchorage and Fairbanks are displayed.

The screen shot above shows what ADS-B coverage at 3,000 agl looks like. Also displayed are two flight routes—a direct flight for those clear days when you can climb to altitude, and the more indirect route past Palmer, through Tahneta Pass, across the Copper River Valley to Isabel Pass, and then on to Fairbanks.  The more indirect route illustrates that there is no coverage in the Copper River area, until you make it through the pass, and are in the Tanana Valley.  With Google Earth, you may define any route you like, and get an idea of where you will or won’t receive the full benefits of the ADS-B system.

RADAR Coverage Included
Another information source is included in this package.  For each of the altitude categories in the KML file, you may also display ATC radar coverage.  This can be helpful if you are trying to determine where, and at what altitudes you might be able to get VFR Flight Following from ATC, which is another handy feature.

Alaska ADS-B Coverage Lacking
There are many benefits of the ADS-B system, but to receive the full value of the system, the airspace you fly in needs to be in coverage.  Zooming out and looking at coverage statewide, it becomes apparent that large portions of the state have no coverage.  AOPA, the Alaska Airmens Association and other organizations have and will continue to advocate to increase coverage across the state. While no ground-based system will ever cover the entire state, we estimate that another 12-14 stations would be required to provide an adequate minimum operational network of coverage.  We continue to work with the FAA to push for more stations, however the cost benefit calculation is in part determined by how many aircraft are equipped to utilize the system.

Benefits Still Exist
While we continue to advocate for improved coverage, there are many safety benefits regardless of coverage.  For example, two aircraft flying opposite directions on a drizzly day under a low cloud layer following the Yukon River half-way between Fort Yukon and Eagle will be able to “see” each other, without the benefits of any ground station, if both are equipped with ADS-B.  This benefit, along with the ability to receive weather information, current pilot reports and NOTAMs from a remote area or while enroute are features that can help improve pilots’ situational awareness and should be considered when deciding if, and how to equip your aircraft. You can use the FAA’s ADS-B coverage map to asses the availability and value for the flying that you do.

Statewide coverage of ADS-B for 3,000 ft agl shows huge holes in coverage across mainland Alaska. AOPA is pushing for additional coverage for the state.

Getting the Tool
To obtain this KML file, go to the FAA’s Equip ADS-B page  https://www.faa.gov/nextgen/equipadsb/airspace/ and select the link to download the Google Earth map.  If you don’t already have Google Earth on your computer, you will need to separately download and install that free program.  The KML file from the FAA encompasses the entire country, and at first may appear overwhelming, as it contains airports and airspace in addition to the ADS-B and radar coverage folders.  After opening the file in Google Earth on your own computer, you may turn off those other features. The FAA includes the Alaska ADS-B and radar coverage in a separate folder, which you may save independently, if you like. Scroll down the list of folders to find the Alaska section.

With this tool, it is easy to look at the places you fly, and see what kind of ADS-B coverage to expect along the routes most important to you. It may help you make an investment decision!


Other ADS-B References that might be helpful:

Online course on ADS-B Basics:  Link directly to an AOPA Air Safety Institute interactive course that provides the basics on what ADS-B is and how it works.  https://flash.aopa.org/asf/ads-b/

AOPA’s ADS-B OUT selector:  A flow sheet to help figure out what equipment might be most appropriate for your flying.  https://www.aopa.org/go-fly/aircraft-and-ownership/ads-b/ads-b-selector

Updated information on the FAA ADS-B Rebate Program: https://www.faa.gov/nextgen/equipadsb/rebate/





Exemption for aircraft without electrical system: