On Thursday, September 28, 2017 at 6:53:44 PM UTC-7, Tom BravoMike wrote:
/snip/
3. Why do so many sources say: You fly above 18,000 ft? Go for 1090. You fly below? Go for 978 ? See in that respect e.g.

https://www.garmin.com/en-US/blog/av...on-is-for-you/

but disregard the specific equipment suggested.
/snip/

Tom

Sounds like you have a great handle on stuff here to help make the right decisions for you.

I would not give too much weight too much to the UAT argument in that blog. it's from several years ago, and suspect it is coming at a time where there actually started to be more 1090ES out installs in GA. Garmin might have had a sales reason around that time to mention UAT product upgrades (on the GLD88) and also may have in part just been echoing the FAAs vision for how ADS-B dual-link was going to be deployed. Today below 18,000' I think it is a good mix of UAT and 1090ES.

Some comments in the strange gymnastics behind dual-link in the USA: Originally the FAA has a view that UAT would be used for all lower altitude aircraft (then below FL240, later lowered to 18,000'), driven by concerns about 1090 MHz congestion, and likely expected costs of Mode S transponders, and likely a desire to create a user base of UAT to make FIS-B successful (and have FIS-B successful to encourage UAT adoption..). And organizations like AOPA and EAA liked the idea of keeping Mode C transponders so liked the idea of UAT, and so on.

.... but much of it is probably not true, Mode S transponders are not hugely expensive (for what they do), the rest of the word ignored UAT and went 1090ES only, so economies of there helped lower prices and will continue to, lots of folks "cheated" and got free FIS-B with portable devices without playing in ADS-B proper, ADS-B Out for many install its easier to upgrade older transponders with plug in replacements (and use existing antenna and wiring etc.) , or do a Mode S transponder firmware upgrade , etc., etc. It's a very complex system and I don't think played out as envisioned early on, really complex systems rarely do.

It seems that lots of GA folks are installing lots of different ADS-B Out stuff, in the mid-high end GA market I see people going with 1090ES Out and Dual-Link In. And not just for people who might fly in class A airspace. Much of that is driven by easy upgrades/add on to their transponders

As for PowerFLARM adoption, glider ports and operations that I know have strong adoption, most people flying cross country have it. The thing that matters is where you fly, if PowerFLARM usage is very low (and not likely to increase) then its a non-issue.

I'm not sure there us somebody else able to develop the software equivalent for ADS-B to what makes FLARM useful between gliders, usable at all in thermals etc. I've seen the issues with PowerFLARM, it was very frustrating, but I think we are on a stable/usable system now.