Steve Ells extols the benefits of ADS-B Out and provides information on a couple of new products in the field.

The Jan. 1, 2020 ADS-B mandate is coming for GA airplane owners. This mandate requires the installation of equipment to broadcast coded information to ATC, and to other aircraft in a format known as Automatic Dependent Surveillance-Broadcast, or ADS-B. 

Why do we need to upgrade to an ADS-B system? 

Simply put, every aircraft equipped with an ADS-B datalink will automatically transmit its precise position, its velocity (both vertical and horizontal), as well as its altitude and other information to controllers and to other nearby aircraft. 

I believe few understand how much safety is enhanced when pilots can display other nearby aircraft in real time on a panel-mounted or portable pictorial display. Prior to the installation of ADS-B Out equipment in my Comanche, I hadn’t grasped how much this benefit would affect my sense of safety while aloft.

Is ADS-B Out required?

Does every owner need to install ADS-B Out equipment to comply with the mandate? The answer is no, but if you’re having trouble with the decision, one rule of thumb suggests that if you are now flying into and out of airspace that requires a Mode C transponder, you’ll need to equip with ADS-B Out. 

The following defines where ADS-B Out is needed after Jan. 1, 2020:

 • All Class A, B and C airspace

• All airspace at and above 10,000 feet MSL over the 48 contiguous United States and the District of Columbia 

• Within 30 nautical miles of airports listed in 14 CFR §91.225, from the surface up to 10,000 feet MSL

• For Class E airspace over the Gulf of Mexico from the coastline of the United States out to 12 nautical miles, at and above 3,000 feet MSL.

In versus Out

The broadcast part of ADS-B known as Out is the sticking point for mandate compliance.

Editor’s note: There is no requirement that aircraft be able to receive ADS-B In information. However, the traffic and weather information provided by ADS-B In are incredibly useful, and you will want to be able to view them in the cockpit. 

Some (but not all) ADS-B Out devices also have In capability and can display traffic and weather data on their own screens. Others can send traffic and weather data to a MFD/PFD or GPS or wirelessly to an iPad or other tablet.

If it’s just ADS-B In you’re looking for, data is easy to capture by using a wide variety of small, relatively inexpensive battery-powered portable receivers from companies such as Garmin, Dual, Appareo (Stratus), Levil and Radenna. There’s even a kit for an In receiver that features what’s known as a Raspberry Pi processor running PiAware software. 

I’ve used a portable Dual XGPS170 978 UAT receiver in the past and have recently upgraded to a Stratux Merlin by Seattle Avionics that has 978 UAT and 1090 ES receivers as well as an internal GPS and an AHRS. The Merlin AHRS provides reference information that syncs with terrain software to provide synthetic vision of the terrain. I use my Apple iPad Mini loaded with FlyQ electronic flight bag (EFB) software from Seattle Avionics to view ADS-B information.

There are still almost two years left to comply with the ADS-B Out mandate. That seems like a long time, but it’s hard to ignore the tick-tock of the clock as days speed by.

978 UAT ADS-B Out solutions

If you never fly above 18,000 feet MSL and don’t see yourself crossing international borders, then a simple 978 UAT (Universal Access Transceiver) installation is sufficient to meet the ADS-B Out mandate.

978 UAT (operating on a frequency of 978 MHz) was enacted to provide a path for small airplane owners to comply with the ADS-B mandate without adding thousands more users to the already saturated 1090 MHz transponder frequency.

The biggest advantage of installing 978 UAT equipment is the additional bandwidth of the frequency (compared to the 1090 MHz frequency). The “bait” the FAA hung out there to convince pilots to install 978 UAT equipment is a better data transfer rate on 978 MHz and the promise of in-cabin weather and traffic info.

Recently a Palo Alto, California company called uAvionix introduced a very simple ADS-B Out system that’s so ingenious it’s laughable. The uAvionix SkyBeacon looks like the left navigation light assembly with a small white blade projecting downward. There’s almost no installation cost since all that’s required is to remove the existing nav light assembly before connecting the existing power and ground wires to the SkyBeacon. Pricing is reported to be targeted at $1,400. Alas, it’s not yet approved for installation in certified airplanes, but the folks at uAvionix assured me that the paperwork is moving through the certification grinder.

Another relatively low-cost 978 UAT solution is the Garmin GDL 82. It’s a small box with a built-in WAAS GPS receiver that is installed in line with the existing transponder coaxial cable. A supplied ADS-B antenna and coaxial cable must be installed on top of the airplane to complete the installation. It is compatible with a wide range of existing transponders. Prices start at around $1,800.

The KGX 150 line of BendixKing 978 UAT Out transmitters start at around $2,400.

The combination of low acquisition cost and simple installations removes the financial roadblock that seemed to be part and parcel of the ADS-B mandate compliance a few years ago.

1090 ES ADS-B Out solutions

If you need to fly above 18,000 feet MSL and/or travel internationally, then you must install a system that transmits on 1090 MHz to comply with the ADS-B mandate. This is often referred to as a 1090 ES system; with the ES standing for “Extended Squitter.” The following definition from an online post on the Garmin website explains squitting: “By definition, the word ‘squitter’ refers to a periodic burst or broadcast of aircraft-tracking data that is transmitted periodically by a Mode S transponder without interrogation from controller’s radar.” 

Even my ancient King KT-76A Mode C transponder shot out a three-parameter squit. A Mode S transponder can squit up to seven parameters, while ES transponders can squit up to 49 parameters of data. 

1090 ES transponders are available from Garmin, BendixKing, Appareo (Stratus), Trig and other companies. 

Is it worth it?

Prior to installing ADS-B Out equipment late last year, I flew for a couple of years displaying ADS-B In data gathered by the Dual XGPS170 mentioned earlier. Data was displayed on my iPad and I was happy to get free traffic and weather information in my cockpit. 

I installed a 1090 ES system from Trig Avionics in my Comanche. In addition to complying with the mandate, what did I gain by installing ADS-B Out?

More than I thought I would, as it turns out. Just to verify my conclusions, I sent the following questions to around 20 of my flying friends: 1.) Why do you like ADS-B Out? 2.) What do you feel is the real advantage of ADS-B Out? and 3.) How do you feel ADS-B Out has enhanced ADS-B In?

Mike Jesch, a flight instructor, big iron captain for American and a Cessna 182 pilot wrote:

Why do I like ADS-B Out? What do I feel is the real advantage?

Two closely related questions. I like the Out because it improves the accuracy of the In data I receive. The real advantage is going to be the ability to receive traffic advisories in areas which don’t have radar coverage like mountainous areas. Even if not talking to ATC, it’ll be great to have accurate traffic information available in our cockpits. Once everybody gets equipped, the accuracy and validity of the data provided to the pilot in real time will be truly amazing.

ADS-B Out has and will enhance ADS-B In, by improving the accuracy and completeness of the traffic information available.

And, it’s important to remember that ADS-B In is not just about traffic. Weather information is now available in near-real time. That can provide amazing strategic planning capability in the GA cockpit.

Mike Filucci, a retired airline pilot, formation flight instructor and VP of the Pilot Information Center and Flight Ops at the Aircraft Owners and Pilots Association (AOPA) answered:

I’ve been flying my RV4 with ADS-B In and Out for the last year and eight months (225 hours) and really like both the In and the Out features. The biggest advantage I find for the Out is really tied to the In on other airplanes—I know other pilots can see me on their screens if they are equipped with ADS-B In and, of course, I can see their airplanes because I have In. Traffic awareness is an important aspect, particularly here on the East Coast where we have a high-density environment. The other big plus of In, as you know, is the ability to see weather radar returns, albeit delayed and access weather information.

Amy Laboda, freelance writer and former editor of Women in Aviation International’s magazine, has been flying ADS-B for years (the mandate was first published in 2010). She wrote:

This [ADS-B Out] is the only way to be sure you are getting accurate traffic info. Period. And that accurate traffic info has been enlightening. Perhaps lifesaving, but who would know, right?

I like that others know where I am, even if just seeing my 1200 squawk and a trend line. And of course, as I said above, I like having accurate traffic info on where others are if they are close to my “bubble” of airspace.

Can’t state it enough: accurate traffic position info.

It has been fascinating watching the ADS-B system build out and watching others adopt a tech that, by the time it is mandatory, I will have been using for nine years.

Eyeball-based traffic avoidance

There’s a segment of the flying public that may argue that their Mark I eyeball provides all the traffic protection they will ever need. That doesn’t work for me.

Years ago, Audrey and I were flying west up the wide and clear Antelope Valley east of Palmdale (California) VOR on our way home from one of AOPA’s famous Palm Springs Fly-ins. We were in AOPA’s completely refurbished Sweepstakes Commander 112. (For more information on that sweepstakes, see Resources at the end of this article. —Ed.)

Displayed on the screen of the then-new Garmin MX 20 MFD was traffic detected by the latest version of Ryan’s traffic advisory system (TAS). The screen showed four aircraft out there. We knew where they were and what altitude they were flying in relation to our altitude. We looked and looked but never saw any of them. To be honest, my eyes have needed correction since I was in fifth grade so maybe an eagle-eyed pilot could have seen them, but I remain unconvinced.

ADS-B Out enhances the ability of ADS-B In receivers to detect other airplanes 

Ken Foster, a retired engineer and pilot of a Cessna 182 who I’ve known for over 20 years wrote:

The real advantage of the system is demonstrated when you see close, sometimes very close, traffic on the panel [display] and cannot find it out the windshield. I am convinced that I have observed conflicting traffic on ADS-B and avoided a midair by varying my course. This has happened three times.

If you don’t have Out you are really not getting the In that will keep you safer. You’re kidding yourself, at least until 2020.

My experience is like Foster’s. Prior to installing ADS-B Out, I always requested flight following from ATC. Since my home airport is in a low traffic area, I almost always got it. But I knew that separating me from other traffic is pretty low on ATC’s priority of services. So, I knew that I had to keep using my “not-so-good” vision as my first defense against midair mishaps. Before ADS-B, what other tool did I have?

ADS-B Out provides a very clear picture of traffic near me. I have altered course when my “enhanced” ADS-B In showed what I felt was converging traffic. I had a transponder code for flight following during that flight, but ATC did not advise me of what I felt was conflicting traffic. 

Today I am more confident due my ability to personally control the responsibility of traffic conflict avoidance. Ensuring separation of VFR traffic is not ATC’s primary job. ADS-B Out puts the responsibility back on me; and provides just the tool I need to take care of business.

Now or later?

There are now several relatively inexpensive methods of complying with the ADS-B Out mandate. Will prices come down more in the next two years? No one knows, but avionics shops tell me that they’re busy now—so the sooner you get on a schedule to get your Out the sooner you’ll have a tool to enhance your In experience with all its benefits, as well as the best existing tool to avoid conflicts with other airplanes. 

Steve Ells has been an A&P/IA for 44 years and is a commercial pilot with instrument and multi-engine ratings. Ells also loves utility and bush-style airplanes and operations. He’s a former tech rep and editor for Cessna Pilots Association and served as associate editor for AOPA Pilot until 2008. Ells is the owner of Ells Aviation ( and the proud owner of a 1960 Piper Comanche. He lives in Templeton, California with his wife Audrey. Send questions and comments to editor [AT] piperflyer [DOT] com 


Garmin, Ltd

Honeywell International, Inc.

Dual Electronics

Appareo Systems, LLC

Levil Aviation

Radenna, LLC

Sandia Aerospace

Seattle Avionics, Inc.

uAvionix Corporation

Trig Avionics Limited



Aircraft Owners and Pilots Association