What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

ADSB Transponder Question

cyrus

Well Known Member
I currently have a Garmin SL70 that works great but is mode C. I also have a gdl39 connected to my G3X touch for ADSB in.

I?m debating for ADSB Out, whether I should add a GDL 82, and live with its 978 restrictions or try to buy a gtx 335 with gps. It?s a $1200-$1400 difference which isn?t negligible. One question is if go with the 335, does my SL 70 have any value in the ADSB era which could help offset the difference.

Thanks
Cyrus
 
Street value of your SL70 is about $350. The mode C market is saturated with trade ins from upgrades to mode S-ES.
You should look at your whole panel. Is there an upgrade to an ifr gps in the future? (It could double as the adsb gps position source).
Are you wedded to Garmin? There are cheaper solutions out there.
UAT vs mode S-ES: UAT limited to below 18,000?; UAT may be a future problem if Mexico or Canada adopt adsb and you want to fly there. Your decision.
 
Buy yourself some time and go for an uAvionix Echo UAT or Garmin GDL 82. I fly one of each. The EchoUAT kit with SkyFX is $400 cheaper than the GDL 82 and is both out and in (for everything except Garmin). In my RV3 I put the Echo in and already had a GDL 39, similar to your set up, so now that airplane will talk to ADS-B "in" with any manufacturer's equipmemt or app.

And don't think there are any real restrictions with UAT (978) unless you are turbocharged and fly over 18,000 feet or plan on crossing the pond to Europe. You will still be good in North America. Mexico won't have ADS-B requirements in our lifetime (I have many Mexican clients, some well connected who scoff at Garmin and FAA stating any kind of ADS-B will be mandated in their country). Canada will require satellite-compatible diversity antenna units so many 1090ES units like the GTX 335 (or ESG etc..) won't help you in the limited areas Canada will have for rule airspace.

Jim
 
Last edited:
UAT 978 is fine

I agree with Jim above. Just install the GDL82 and be done with it. Don't over think it.
 
Thanks, these are amazing answers and covering all my concerns. I do hope to fly both to Mexico and Canada, but didn?t consider all these points.

I was looking at the UAT unit as well, price point is appealing. Since my G3X already has hardwired in with GDL39, what difference would the UAT (box &gps) vs GDL 82 offer i ok inside of in comparability with other manufacturers.

Is GDL 82 hardwired to the transponder or do they both function similarly?
Setup sounds easier on the UAT.

Again, thank you!
Cyrus
 
By all means keep your GDL 39 in place. It is one of the best "in" solutions available for G3X and Garmin portables and apps.

Both the GDL 82 and. EchoUAT interface wirelessly to the existing transponder so neither require wiring to transponder. There is an option to wire the Echo to a GTX-327 forncontrol but that just adds complexity. Both are 978mHz UAT solutions. Both units require GPS position from an external source like the GA35 antenna for the GDL 82 or SkyFX gps for the Echo. Alternatively either unit can get a position from a TSO'd WAAS IFR navigator like a GTN, GNS, IFD etc. which eliminates adding a seperate GPS antenna.

EchoUAT: more bang for the buck but requires adding another transponder antenna to the belly. Anonymous mode must be selected via uAvionix phone application and resets itself to non-anonymous and stays that way if ever a discrete code other than 1200 is entered and won't talk to the phone app in flight to switch back to anonymous. Has an additional perk of having an out signal to feed apps like ForeFlight, iFly, FlyQ, Avare etc.... basically anything but Garmin apps or hardware. The Echo might take some initial fiddling with settings to optimize signal using the uAvionix app then be good for the long run. The unit is in a housing sized smaller than a cigarette pack that uses an included pre-wired Molex connector harness.

GDL 82: a few hundred more expensive but does not require an additional belly antenna. Benefit of a hardwired switch for anonymous mode and latest software update makes sure the unit stays anonymous during boot up and can be selected on or off during flight. Also requires no additional settings or optimization during install and testing. The GDL 82 is built like a tank and reflects Garmin quality and sturdiness. It requires a harness be made hut isn't to big a deal if someone can solder and has access to a specialty avionics crimper for high-density male D-Subs.

Jim
 
Buy yourself some time and go for an uAvionix Echo UAT or Garmin GDL 82. I fly one of each. The EchoUAT kit with SkyFX is $400 cheaper than the GDL 82 and is both out and in (for everything except Garmin). In my RV3 I put the Echo in and already had a GDL 39, similar to your set up, so now that airplane will talk to ADS-B "in" with any manufacturer's equipmemt or app.

And don't think there are any real restrictions with UAT (978) unless you are turbocharged and fly over 18,000 feet or plan on crossing the pond to Europe. You will still be good in North America. Mexico won't have ADS-B requirements in our lifetime (I have many Mexican clients, some well connected who scoff at Garmin and FAA stating any kind of ADS-B will be mandated in their country). Canada will require satellite-compatible diversity antenna units so many 1090ES units like the GTX 335 (or ESG etc..) won't help you in the limited areas Canada will have for rule airspace.

Jim

If you run a wire from your certified GPS, the echoUAT is almost $800 cheaper. If your transponder is relatively new, I cannot imagine why anyone would spend big bucks on another upgrade - by the time one or the other wears out, something else will likely be mandated anyway...
 
You will still be good in North America. Mexico won't have ADS-B requirements in our lifetime (I have many Mexican clients, some well connected who scoff at Garmin and FAA stating any kind of ADS-B will be mandated in their country).
Jim
I don't know where you got this information but these are the current requirements, as published by the Mexican General Civilian Aviation Authority (DGAC) in 2015: <APPLICABLE SECTIONS - TRANSLATED>

1) As of January 01, 2018, unless otherwise authorized by ATC, no aircraft may fly in Class E airspace over the Gulf Of Mexico at or above 3,000 ft MSL beyond 12 Nautical Miles from the Mexican coastline unless the aircraft is equipped with an ADS-B Version 2 system transmitting on 1090 MHz

2) As of January 01, 2020, unless otherwise authorized by ATC, no aircraft may fly in Class A airspace unless the Aircraft is equipped with an ADS-B Version 2 system transmitting on 1090 MHz

3) As of January 01, 2020, unless otherwise authorized by ATC, no aircraft may fly below 18,000 ft MSL AND in the following airspace unless the aircraft is equipped with an ADS-B Version 2 system transmitting on 1090 MHz

a. Within Class B and C airspace

b. Within 30 Nm of the Mexico City International airport from the surface up to 10,000 ft MSL

c. Over Class B and C airspace within the lateral boundaries of the airspace up to 10,000 ft MSL

d. Within Class E airspace over Mexican territory at, or above, 10,000 ft MSL except when below 2,500 ft AGL

4) All aircraft with ADS-B equipment must be transmitting at all times

5) Any requests for deviations from this rule must be submitted to the ATC facility with jurisdiction over the airspace in question based on the following timelines:

a. To request authorization for the operation of any aircraft with an inoperative, installed ADS-B equipment for a flight to its destination, including intermediate stops or to a repair facility where reparations to the equipment can be performed, the request can be made at any time

b. To request authorization for the operation of any aircraft without an installed ADS-B equipment, the request must be made at least 1 hour prior to the anticipated departure time.


This ICAO standard, which Mexican Civil Aviation Authorities have already implemented, is basically what the FAA has mandated for aircraft within the US.

:cool:
 
Last edited:
4) All aircraft with ADS-B equipment must be transmitting at all times


Sneaky totalitarian bastages! I had planned on having my echoUAT separately switched, and simply "forget" to turn it on for flights not headed to any of the airspaces otherwise prohibited. Now, I'll have to rig it so that it is removable...

:D
 
I don't know where you got this information but these are the current requirements, as published by the Mexican General Civilian Aviation Authority (DGAC) in 2015: <APPLICABLE SECTIONS - TRANSLATED>

Because there is Mexico and then there is Mexico. Unlike the USA, Mexican laws, regs and proclamations are beyond interpretation. I have lived in and around both countries my whole life and my family has had businesses in both countries dating back to the 50's.

In Mexico it is more about who you know and what inside information you have access to. I have many friends and clients from Mexico and some are in major industry and government. Many travel back and forth in aircraft with N numbers smaller than 12 inches too. Go figure. And they are smart enough not to register their aircraft in Mexico. I have installed more UAT systems in Mexican aircraft than 1090ES because they are interested in ADS-B when in the US and couldn't care less about it in Mexico. In fact the 1090ES generally are installed if they plan on flying at 18,000 ft or above and not for international ops. They all laugh when the alledged Mexican mandate comes up in conversation. One pointed out they don't even have much radar in Mexico and there is no way their federal government is going to spend any money on ADS-B. Remember as stated there is Mexico and then there is Mexico.

Basically grand proclamations from the "us too" DF stating intentions to look compliant with the rest of North America and a practical capability check won't jive. In yesterday's AOPA/FAA ADS-B webinar it was stared there is no mandate in place in Mexico and ADS-B is not required for crossing international boundaries. But the Mexican regs as quoted above say there have been some sort of mandate in place since 2008 with more kicking in January 1. Horse feathers. FAA flight standards say the existing ADIZ requirements will stay intact meaning only Mode C will be required for entry on the US side with the only change for unequipped aircraft being having to find a US port of entry airport outside of rule airspace. That goes for both Mexico and Canada.

I wish written regulations in Mexico were real like we have here at home. But the reality is Mexico operates under moldable rules that vary every mile and is in a constant state of corruptive flux masked by proclamations of legitimate rule of law.

So I am not saying that Mexico doesn't have rules addressing ADS-B. It does. It won't mean anything for decades or longer. But if an aircraft owner wants to hedge their bet and belives in official Mexican rule then 1090ES is the way to go for comfort. Meanwhile, reality, as is most things in Mexico, is not as officially advertised.

So by all means go with a 1090ES system if that eases your mind. Meanwhile here at the border fence (I can throw a rock across it) we will carry on with business as usual. ��

Jim
 
Last edited:
Sneaky totalitarian bastages! I had planned on having my echoUAT separately switched, and simply "forget" to turn it on for flights not headed to any of the airspaces otherwise prohibited. Now, I'll have to rig it so that it is removable...

:D

Don't forget that the same situation exists in the USA ADS-B rules. If an aircraft is equipped, the ADS-B equipment must be on and operating at all times the aircraft is operated. No matter the location. Even if on the ground taxing at your large ranch in Montana hundreds of miles from rule airspace, if equipped... it must be on an operating per the rule. Ridiculous, yes. But I wonder where we (and AOPA and EAA) were when they slipped that language into the rule.
 
Last edited:
Because there is Mexico and then there is Mexico. Unlike the USA, Mexican laws, regs and proclamations are beyond interpretation. I have lived in and around both countries my whole life and my family has had businesses in both countries dating back to the 50's.
So stereo typically biased I won't even begin to answer, especially since your original post wrongly stated:
You will still be good in North America. Mexico won't have ADS-B requirements in our lifetime (I have many Mexican clients, some well connected who scoff at Garmin and FAA stating any kind of ADS-B will be mandated in their country).
Jim
So if you want to fly in Mexico (or just about anywhere else in the world) don't listen to those that have no idea, equip with 1090Mhz.

FWIW: Get away from the US/Mexico border and you will find a much different Mexico than the "news" shows. I have flown in Mexico for years (still do) and I (not just my family) have "lived in and around Mexico "since the 60's.

:cool:
 
Last edited:
My impression is that Mexico is kind of like Canada, in that it has a large land mass relative to it's population, and fewer airports per capita as well. This may not be accurate, but i'm open to being corrected.

If it is, it would make a lot more sense for Mexico to jump on the Satellite ADS-B bandwagon that Canada and the rest of the world are using. 1090ES based, either with diverse antennas (to explicitly satisfy the US when they visit) or a single sky-pointed antenna and the (not unreasonable) expectation that it will still be strong enough for ground-based towers to pick up as well.

Apart from the cost of re-equipping all of the aircraft that went with UAT (and maybe that it "wasn't invented here"), I wouldn't be surprised to see the FAA switch to satellite-based for 1090 reception at some time in the future.
 
Apart from the cost of re-equipping all of the aircraft that went with UAT (and maybe that it "wasn't invented here"), I wouldn't be surprised to see the FAA switch to satellite-based for 1090 reception at some time in the future.

I thought the whole US rationale for UAT was the fear of frequency congestion, if a single frequency was used. What will happen if every US aircraft has to access a single geosynchronous satellite on one frequency?
 
LEO

I thought the whole US rationale for UAT was the fear of frequency congestion, if a single frequency was used. What will happen if every US aircraft has to access a single geosynchronous satellite on one frequency?

The Aireon payload is on an Iridium NEXT satellite which has a low polar earth orbit. There are 66 (65 according to aireon) operational satellites with 9 spares loafing around.
https://en.wikipedia.org/wiki/Aireon

I still wonder about potential congestion too, but it would not be as bad as having a single GEO satellite.

From Aireon:
https://aireon.com/1090-global/back-basics-part-3-ads-b-data-not-average-aviation-data-set/

Given current analyses of Aireon’s data and payload performance, the future is looking bright. To date, 65 Iridium® NEXT satellites are currently in orbit, each hosting an Aireon payload, with 60 of the 65 operational. Even with just over 90 percent of the constellation complete, the data being received has exceeded expectations, not only in terms of accuracy, but in volume. For instance, after just the first two launches (that’s only 20 payloads in orbit, so less than a third of the constellation) Aireon received over six billion ADS-B position per month. Since then, the volume has increased to over 10 billion position reports per month, with an expected 25 billion reports per month once the constellation is complete.

In addition to the incredible volume received thus far, the next incredible technological observation came with the types of vehicle ADS-B broadcasts detected by the Aireon system. As expected, the team saw position reports from commercial aircraft, business jets and general aviation aircraft. But, when the engineers noticed data from unmanned aerial vehicles (UAVs) and surface vehicles, such as airport maintenance vehicles, helicopters and balloons, the team knew the power of the payloads was incredible. This kind of performance is a testament to the strength of the Aireon system, and is an indicator towards the level of accurate data and reports to come soon with a completed network.
 
Last edited:
My impression is that Mexico is kind of like Canada, in that it has a large land mass relative to it's population, and fewer airports per capita as well. This may not be accurate, but i'm open to being corrected.
That is very true, but also applies to the US. In Mexico, Canada and the US there are huge areas where ADS-B will not be required. However, ADS-B will be required in most areas where humans want to fly so I recommend you equip accordingly.

:cool:
 
That is very true, but also applies to the US. In Mexico, Canada and the US there are huge areas where ADS-B will not be required. However, ADS-B will be required in most areas where humans want to fly so I recommend you equip accordingly.
True, but in the US you have something like 10x or 20x the number of airports and pilots compared to Canada, and a much smaller land mass... ergo the cost per capita to cover the country with ADS-B towers is much lower.
 
Back
Top