GARMIN TIPS & TRICKS ADS-B: Two Years and Counting

The ADS-B mandate is only two years away, a relatively short time given the task ahead. Figures from AOPA show that there are roughly 225,000 General Aviation aircraft, and the FAA expects between 100,000 and 160,000 of these will need ADS-B “Out” to operate in airspace they expect to transit. (see https://www.faa.gov/nextgen/equipadsb/levels/). Data from this site shows approximately 33,000 have already been equipped, so with 104 weeks left in the next two years, only 520 work days remain (at 5 days a week) to install your ADS-B system. One estimate from the web claims there are 340 avionics shops in the U.S. capable of doing these installs. So the math is simple. About 67,000 to 127,000 installs must be done by those shops, at the rate of 133 to 252 per day on average, or about 2 to 4 per week (for 2 years) for each shop. This could tax those resources if too many people wait until 2019.

 The primary question for those ready to install an ADS-B system is, What works for me? As choices continue to expand, decision-making gets more difficult, and can lead to further procrastination because you believe something better and less expensive will be out soon. That may be true, but beware of the coming crunch in scheduling shop time.

Your system choices should be influenced by several factors. What pertinent devices are already in the airplane—EFIS, MFD, or other moving-map displays? Which GPS systems do you have? Device compatibility is an issue so you need to make sure additions work with your installed equipment. And, of course, operating in the flight levels requires a 1090 MHz Mode ES (extended squitter) transponder, so the UAT options (978 MHz) are not applicable. The most important question, however, is which GPS/Transponder can you choose? Each permitted pairing must be TSO’d for your aircraft. These approved pairings are found on the FAA website https://www.faa.gov/nextgen/equipadsb/equipment. This question of compatibility is sufficiently complex that you should spend time talking to a knowledgeable avionics shop, preferably one that has done Twin Commander installations.

Figure 1. The Garmin GTX 345 ($4,995), having both ADS-B “In” (dual band) and “Out” on 1090 MHz. An internal WAAS GPS is available for an additional $800. You can connect with FlightStream to a tablet using the Garmin Pilot or ForeFlight App.

The minimum requirement to meet the mandate is to transmit your GPS position (ADS-B “Out”). But an early decision you should make is whether you want a panel-mounted option for traffic and weather (ADS-B “In”), or will you rely on TCAS and satellite weather or on a portable “In” solution. Here you should be aware of the position errors with TCAS (ADS-B traffic is more precise) and of the limitations of ADS-B weather. Satellite weather is available on the ground, and has higher resolution than ADS-B weather, particularly with weather outside of your ground station area. Some options allow the merger of traffic from each source, with an algorithm for picking the best one at the moment. Also, with some setups, a choice can be made on the display screen to look at weather from either source.

Figure 2. The L3 Lynx NGT-9000 ADS-B In and Out, with internal WAAS GPS, built in display screens, and a Wi-Fi link to an iPad with ForeFlight.

Let’s assume you want both “In” and “Out” with panel-mounted equipment displaying both traffic and weather. Popular choices include the Garmin GDL 345 in Fig. 1 and the L3 Lynx NGT-9000 in Fig. 2. The Garmin will display on their G500/600 EFIS or the GNS 430W/530W or the GTN 750 (and use those GPS units for the transponder position source). It will send traffic and weather to a tablet via Wi-Fi with the Garmin Pilot or ForeFlight App. The Lynx has an internal WAAS GPS and displays data on the unit itself, and also connects via Wi-Fi to the iPad or iPhone using ForeFlight.

If you only want ADS-B “Out” there are other 1090 MHZ options, like the Trig TT31 or King KLN 94. These are certified with GPS units from Garmin or the FreeFlight 1201. Appareo makes the Stratus ESG with internal WAAS GPS, and Avidyne has their AXP340 that couples with the GNS 430W/530W or Avidyne 4xx/5xx GPS position sources. It can be paired with a TAS600A for traffic and weather and display on a range of screens.

The number of ADS-B options continues to increase as manufacturers are rising to the challenge of “more, better, cheaper.” Some of the solutions are quite simple, like the new Sky Beacon ($1,499) from uAvionix, which simply replaces the navigation light on your wing tip and has a built-in WAAS GPS and antenna. Garmin has a unit (GDL 82 for $1,795) with built-in WAAS-GPS that interrupts the cable from your transponder to its antenna, passing the transponder signal through the box and adding ADS-B “Out” going to the antenna. Each of them should be certified in early 2018. But their signals are UAT transmissions on 978 MHz, therefore of no help in a turboprop Commander that operates above 18,000 feet. But if your other ride is a Cub, take note. While not applicable to a Turbo Commander, these new devices nonetheless illustrate that innovative ADS-B solutions are a regular happening.

Figure 3. The new Scout Dual Band receiver from uAvionix, coupled to a tablet for traffic and weather, for ADS-B “In”.

Simplicity in ADS-B “In” systems can benefit everyone. For example, if you just equip with ADS-B “Out” to satisfy the mandate, you may still want the superior position accuracy of ADS-B traffic reports. This can now be done with the uAvionix Scout ($199), shown in Fig. 3, which resembles a USB stick hanging from a small suction cup on a window. This is a dual-band receiver sending traffic and weather data to your iPad (with ForeFlight) via Wi-Fi. With a USB charger on your panel (useful for your tablets, too) you can avoid using their small charger pack for power. For simplicity it’s a generation ahead of the larger portable units from Dual, Garmin, Stratus, Clarity, etc. that were typically set on top of the dash.
In conclusion, this article is not intended to be an exhaustive survey of what options you have, but rather is intended to discuss the relevant considerations in making your choices. It should also be read as a call to action to avoid the rush that will surely come as time runs short.

Keith Thomassen, author of GPS manuals and workshop trainer, earned his first pilot’s certificate in 1958 and pursued a professional career of scientific research and teaching while expanding his aviation interests. With a PhD in Electrical Engineering from Stanford University, he carried out research and teaching at Stanford, MIT, Los Alamos National Laboratory, the Lawrence Livermore National Laboratory, UC Berkeley, UCLA and Harvard. He is a Flight Instructor with Airplane, Instrument and Glider ratings. Contact him at www.avionicswest.com.