On Wednesday, February 15, 2017 at 10:58:45 AM UTC-5, Sarah wrote:
It's not guaranteed you will be 'seen' by a ground station at low altitude, especially out in the boonies or in the mountains. This site supposedly shows coverage by altitude interactively:

https://www.faa.gov/nextgen/programs/adsb/ICM/

Take it with a grain of salt - I saw "0 towers" in central WI last year on the way to Oshkosh at 3000' AGL.

I'm curious what people flying with ADS-B in NV or UT see for ground station coverage.


On Tuesday, February 14, 2017 at 9:30:57 PM UTC-6, Paul Villinski wrote:
Wondering if ADS-B equipped aircraft have any advantage should they need search and rescue, given that they broadcast their ID and coordinates. Is positional information logged by the ground stations, and retained for any period of time, or is it "real-time" only? If retained, it seems that ADS-B could supply search and rescue with a last known fix and trajectory if needed.

Of course, used in a glider, this might create some consternation if an ADS-B breadcrumb trail shows a glider making an off-airport landing....

Debating whether to add the new Trig TN72 GPS unit and TA70 antenna to the Trig TT22 transponder in my Experimental glider, for a legal TSO-C199 "TABS" ADS-B system. Can't quite get a handle on the value of ADS-B out vis-a-vis traffic avoidance, versus simply using the Mode S transponder as is. However, if ADS-B out could provide useful tracking in the event of an emergency, that added value would be significant.

How were you looking for ADS-B towers in WI? When I flew from Chicago to MSP last spring, I had ADS-B ground station coverage with TIS-B for the entire trip. Granted, I was somewhat higher than 3,000 ft. The FAA ADS-B map shows ground station coverage for most of the state at 3,000 ft, which I would suspect is quite accurate.

This summer, I flew from MSP to Bozeman, Reno, Albuquerque, Charlotte, and finally Naples FL. Again I had ADS-B ground station coverage with TIS-B for virtually the entire trip. For much of the trip out west, I was at 14,500 ft MSL. At lower altitudes, I'm quite sure that I would not have had coverage in many of the remote areas. In addition, TIS-B may not be useful, even if you are within range of an ADS-B ground station, if you are at an altitude where transponder equipped aircraft are below radar coverage, and are not visible to ATC.

In 2020, which is only 3 years out, a large majority of aircraft are going to be ADS-B OUT equipped, and as long as you have a dual band ADS-B receiver, you'll be able to see all of that traffic, regardless of altitude throughout the US.

As far as search and rescue goes, don't underestimate the value of amateur run ADS-B receivers that feed traffic data to FlightAware and FlightRadar24.. In many cases the coverage for these receivers is much better than the FAA's network. The GermanWings crash in the Alps a couple of years ago was a great example. FlightRadar24 was able to collect FMS data from their ADS-B receiver network that was available to crash investigators within an hour or two of the crash.

If you fly regularly in a remote area, or are organizing a contest, you can setup your own ADS-B ground station and integrate it into the FlightAware / FlightRadar24 network with a total investment of ~$200 and an internet connection.