Does Your ADS-B Work?

Magical black boxes that supposedly send information to send information to somewhere else with nothing coming back, can leave you wondering if they work. I decided to find out.


Living in the world of email makes life easier, but can often be exquisitely frustrating. Each day I receive numerous emails, both from people I know, plus, of course, the unwelcome stuff we all get. Most of these emails are requesting a response from me. The frustrating part is when I respond to them, I’m too often met by silence. What happened to the sense of urgency? Did they get my response? Did they hear me?

When flying with a friend in his ADS-B Out-equipped Mooney, we began to wonder the same thing, but I’m getting ahead of myself.

The Basics

A few years back the FAA announced its upcoming NextGen project to revolutionize Air Traffic Control and enhance our own safety. The foundation of NextGen is the ADS-B (Automated Dependent Surveillance-Broadcast) system. As you probably know, ADS-B is a cooperative surveillance technology in which an aircraft determines it position via enhanced satellite technology (read WAAS) and broadcasts it, enabling the aircraft to be tracked via ATC ground stations as well as other aircraft. It is supposed to allow more operations in an already crowded system and enable fewer delays. In order to get us to sign up early, the FAA provides some value-added extras, like the ability to receive weather and traffic through the ADS-B In to the airplane. Presumably, this will entice us to equip our aircraft with ADS-B Out.

Lately much has been made of the progress on the ADS-B portion of NextGen both on the ground as well as in the air. The DOT recently reported that the FAA had installed 663 of the ground stations required for the ADS-B infrastructure. However, there seems to be issue if this coverage is enough for ATC to hear all the transmissions. Some people have recently taken the plunge in equipping with ADS-B Out in advance of the mad rush that is sure to happen over the next few years to meet the 2020 deadline, barring some decision change by the FAA (not likely to happen). How is it panning out?

Something Missing?

A friend who flies a Mooney Ovation already equipped with ADS-B, recently told me a story. He had taken a flight and noted that traffic 1000 feet above him wasn’t present on his ADS-B In display but was being worked by ATC. ATC remarked that there had been some radar issues in the area, even though ADS-B doesn’t work through the radar infrastructure. Since this other aircraft wasn’t being “heard” by his ADS-B, my friend wondered about his own installation and how it was performing. If his “In” portion seemed to be faulty, then what about his “Out”? Was it working? Based upon the report by the DOT, and my friend’s experience, how would any of us know?

Like my friend with the Mooney, the owner of the plane I operate has recently installed a Garmin GDL 88 datalink transceiver tied to a GNS 430W (for ADS-B In and Out). Recently, we picked up the plane to see how the upgrade went. The In portion worked to receive traffic (at least that we know of) plus we got weather. However, how were we to know if we are being heard? As far as I know, there is no test an avionics shop can perform to see if it’s working. My research led me to discover that there are two ways to verify the “Out” portion is working.

FAA Report on Your ADS-B

During the installation, I found out that the FAA has created the means to verify our installations. Upon completing a flight (the longer the better), send an email to [email protected]. Include the N#, the type of navigator (in this case a Garmin 430W), the make and model of the ADS-B installation (once again in this case a Garmin GDL 88), the date of the flight, and you might also include the departure and destination airports. Within a day or so you will receive an email with a report attached.

On the first page of the report (depicted on the previous page) you will see the tail number as well as the unique ICAO designator of the aircraft. Immediately following is the major section of non-compliance issues that were identified. If there is a check in any of the four boxes then it’s time to return to the avionics shop to let them sort out the issues. The final section of the first page includes the name of the owner and the date of the report.

The second page of the report (shown here) includes a unique operation id that is tied to the specific flight being checked. Once again, it includes ICAO and tail # info. The duration is the number of seconds that the flight was being tracked via ADS-B and the processed section includes the number of ADS-B transmissions received during that period. Below is the ATC facility that performed the tracking. The columns in the percentage bar show the percent of error and the last five show the success in transmission values. These are a summary of the detailed values found on pages 3 and 4.

Finally the last page (not depicted here) shows the general signal quality. The report may be overwhelming, but is also color coded. If there are any areas with issues, the boxes are colored in red.

If you have an ADS-B installation (or rather, when you have an ADS-B installation) you might want to take the time to have a report issued to you. Included will be a second attachment that explains the report in much more detail and accuracy than what I can cover here.

…Or Use FlightAware

FlightAware is a free website that many pilots use for planning, flight tracking and checking traffic flow in and out of airports. One of its features is the ability to track any IFR flight by use of the tail number. When referencing a particular flight, for a particular plane, a flight map is provided. Along with that is the ability to pull up a track log of ATC “hits” on the plane. If your ADS-B installation is performing as needed, some of these hits will come from the ADS-B rather than just the radar. This way of checking your ADS-B Out is quicker and simpler, but less precise and far less detailed.

If you’re like me, it’s important to know that the equipment in the plane is working. These two ways serve as confirmation that the ADS-B box in the back is more than just ballast. It’s still difficult to know easily if someone received our email, but at least there is a way we can be sure that the FAA is hearing our aircraft.

Howard Drabek, a Catholic priest in League City, Texas, holds commercial, instrument and multi-engine certificates, is a dispatcher and advanced and instrument ground instructor.


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