ADS-B vs. SiriusXM

ADS-B vs. SiriusXM

Perhaps the most significant safety improvement in aviation in the last 20 years is the availability of cost effective, quality, real-time weather and traffic in flight. Once found only on high-end corporate aircraft, real-time weather is now available to any pilot with an iPad using a portable receiver. The most popular portable options are the Stratus 2S ADS-B receiver from Appareo and the SXAR1 receiver from SiriusXM Aviation.

I did a side-by-side comparison of both systems with each receiver dedicated to one of two iPads. My test flights were conducted in a single-engine piston and a single-engine turboprop. 


Both receivers are small and lightweight. Both utilize rechargeable lithium-ion batteries with a life span that exceeds the average fuel leg in most General Aviation aircraft. The Stratus 2S has an eight-hour battery life, while the SXAR1’s battery life is up to six hours. In-flight recharging is easily accomplished with a USB cable, if necessary. 

The light weight of both devices makes a suction cup window mount or a piece of Velcro on the glareshield two practical solutions for mounting the receiver. Both units are simple to operate, featuring exactly one button to turn the unit on or off. 

Both units use indicator LEDs to identify which functions are operating and the status of the battery power. In flight, both receivers display weather in real time on an iPad. 

I use ForeFlight in my cockpit, and both receivers are compatible with ForeFlight. Though some tech-savvy users claim to have made these receivers work with other apps, only ForeFlight is officially supported.


Though both units provide weather information, they do so in very different ways. 

Stratus 2S and ADS-B

The Stratus 2S utilizes the government-developed Automated Dependent Surveillance Broadcast, commonly referred to as ADS-B. 

ADS-B weather is ground-based and subject to line-of-sight limitations; that’s why it’s typically not available when the aircraft is on the ground. Additionally, there are “holes” where ADS-B reception is intermittent. Since ADS-B is the cornerstone of the Next Generation (NextGen) air traffic control, the FAA says that when the system is fully operational in 2020, any in-flight reception issues should be resolved. 

Geographic coverage for ADS-B extends about 20 miles beyond the United States’ borders. On our trips to the Bahamas, we receive ADS-B coverage to about 30 miles offshore at 10,000 feet—our altitude and the lack of terrain obstructions allow the signal to reach farther. 

The weather products available with ADS-B are adequate for the average General Aviation mission. When in flight, composite NEXRAD is available. Base reflectivity and cloud coverage are available on the ground using an internet connection, but not in the air. 

Airborne ADS-B also provides METARs, TAFs, SIGMETs, AIRMETs, TFRs, visibilities, ceilings and flight conditions for graphic display and in text format; notams and Special Use Airspace alerts are also available.

ADS-B with the Stratus 2 includes features you cannot get from SiriusXM Aviation weather. Traffic and a backup PFD are phenomenal features provided by Stratus. I love the backup PFD. I teach my students how to shoot an approach with it in the event of a total equipment failure. 

If your aircraft does not have a traffic avoidance system, ADS-B traffic is useful, but until 2020—when all aircraft are supposed to be equipped with ADS-B—it does not depict all traffic. 

The best part of ADS-B is that the service is free, while SiriusXM uses a paid subscription. However, the receiver to get free ADS-B data can cost more up front: a Stratus 2S lists at $899, not counting any antennas. In contrast, an SXAR1 is priced at $699, and may qualify for a $200 rebate, but subscription fees will be extra.

SXAR1 with SiriusXM Aviation weather

The Sirius product, SXAR1, gets its data not from the ADS-B source, but from SiriusXM satellites. It also has a GPS/WAAS embedded receiver. 

The SiriusXM aviation weather subscription includes the same weather products provided by ADS-B, as well as icing icing, winds aloft, lightning, in-flight base reflectivity radar, radar echo tops, cloud tops, turbulence and surface analysis. The range of coverage includes most of Canada, parts of the Caribbean, and extends much farther offshore. 

A subscription for the SiriusXM Pilot For ForeFlight package is around $40 per month. More comprehensive weather information is available with Pilot Preferred ($59.99/month) and Pilot Pro ($99.99/month) packages. For all SiriusXM aviation weather packages, the ability to listen to your favorite music and news channels in flight, if you so choose, can be added to your weather subscription at a discounted rate. 

One unexpected  issue arose with the SXAR1 receiver during my testing. The electrically-heated windows in turboprop airplanes interfere with data reception. Moving the unit to an unheated side window improved my reception. Depending on which side of the plane the receiver was placed also affected the unit’s ability to receive data from the satellite. (We contacted SiriusXM and about this and received this reply: “Heated windscreens on some aircraft may block or interfere with the SXAR1 Receiver data reception. If you experience a weak signal condition, place the SXAR1 close to either side window or you may choose to purchase an optional External Antenna at or at The antenna can then be placed in the cockpit for best signal and the SXAR1 receiver can be placed out of the way.” —Ed.)

Another difference to address is the display resolution. The resolution is the same for the SiriusXM Aviation via SXAR1 and for ADS-B through the Stratus 2 when viewing weather within 200 nm of the aircraft. Beyond 200 nm, the resolution of the SXAR1 really shines; beyond that range ADS-B reduces the radar resolution, making the radar appear more coarse and pixelated. SiriusXM is consistent with its resolution at longer range. 

Final thoughts

Do you have to choose one over the other? When flying with both units, you do not need to choose only one to use because SXAR1 connects because SXAR1 connects to your iPad with Bluetooth, while Stratus utilizes Wi-Fi. This means you can have both at the same time—on the same iPad. Playing with the displays of Stratus on the backup PFD and the SXAR1 shows the advantages of each; the advanced weather features and better range of the Sirius product and traffic on the Stratus. 

Is SiriusXM worth $39.99 a month? It is to me. From my observations, I can say that I love SiriusXM Aviation weather. Since I regularly fly in real weather, the echo tops, icing and selectable winds aloft features make a difference for me. I love that the weather data is usually loaded and displayed before I take off. I do a fair bit of flying in the Bahamas and XM’s radar coverage, particularly when trying to cross the Gulf Stream, is very useful. 

I have had SiriusXM weather in my plane for 12 years, but it is displayed on a Garmin 530. The limitations of the older Garmin devices preclude receiving all the benefits of the service. The portable SXAR1 unit coupled with an iPad allows a pilot to receive every benefit of the SiriusXM service. The value of in-flight real-time weather cannot be emphasized enough. 

For the owner-pilot who must comply with the ADS-B mandate by Jan. 1, 2020, it is typically far less expensive to install an ADS-B Out-only transponder and buy a portable ADS-B In receiver than to purchase a combined ADS-B Out+In device. A portable receiver allows these operators to enjoy the benefits of ADS-B In—without the installed-in-the-aircraft cost. 

In addition, the portability of the Stratus 2S and the SXAR1 are perfect for a pilot like me who flies several different aircraft. 

The SXAR1 receiver delivers the most complete and comprehensive in-flight weather data available on a portable device. The safety features in the Stratus 2—especially after the ADS-B Out mandate takes effect—are phenomenal. I plan to carry both. 

Michael Leighton is a 11,000-hour, three-time Master Flight Instructor and an A&P mechanic. He operates a Part 141 flight school in South Carolina and South Florida. You can find him on the web at Send questions or comments to



SiriusXM SXAR1

Stratus 2S


SiriusXM Aviation

What Can ADS-B Out Do for Me?

What Can ADS-B Out Do for Me?


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 own aircraft, 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

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

• 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 own aircraft. 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 RV-4 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 many 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, see the Commander Countdown in 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 lives in Templeton, California with his wife Audrey. Send questions and comments to


Garmin, Ltd

BendixKing/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