Oops left off thing...

TIS-B broadcasts information for SSR targets, it requires
1. Your aircraft has a transponder
2. Your aircraft is within SSR coverage
3. The TIS-B client aircraft has ADS-B In
4. The TIS-B client aircraft has ADS-B Out that is correctly configured to describe it's ADS-B In capabilities.
5. The TIS-B client aircraft is within ADS-B ground service coverage.


On Sunday, September 24, 2017 at 3:32:38 PM UTC-7, Darryl Ramm wrote:
On Sunday, September 24, 2017 at 11:59:19 AM UTC-7, WaltWX wrote:
On Thursday, September 21, 2017 at 7:31:32 PM UTC-7, Darryl Ramm wrote:
Walt, I think you are misunderstanding what Trig wrote. A TN72 GPS Source will be seen by everybody. That is why anybody doing ADS-B Out in an experimental glider with a TT22 should be equipping with at least a TN72 (or TN70, TN70 required for certified gliders).

Darryl,


Everybody need to stop saying "ADS-B Out" and say 109ES Out or UAT Out where it matters. I try to only say ADS-B where the link layer does not matter. Saying "ADS-B" where you need to be clear about 1090ES or UAT is as useful as saying "TSO" without being clear if we are talking about TSO-C145 or TSO-C199, and can cause much confusion.

OK, I'm clear now that a TN72 GPS Source from a Trig T22 will make me officially visible to all ADS-B in equipped aircraft.

Well all aircraft with 1090ES In, or via ADS-R if they have UAT In (and it's properly set up with some type of ADS-B Out etc.) and in range of ADS-B ground stations.

I am still trying to figure out why I would want to equip with any kind of ADS-B out in my T22 equipped glider:

1) It would be great (but not necessary) to be seen by all ADS-B equipped aircraft. But, with ADS-R (rebroadcast) won't those other aircraft see me anyway since I'm equipped with a Mode-S Trig transponder? I suppose at low altitude where ADS-R is not available, direct receipt of my ADS-B out would be an advantage.

ADS-R no, you are confusing ADS-R and TIS-B.

TIS-B broadcasts information for SSR targets, it requires
1. Your aircraft has a transponder
2. Your aircraft is within SSR coverage
3. The TIS-B client aircraft has ADS-B In
4. The TIS-B client aircraft has ADS-B Out that is correctly configured to describe it's ADS-B In capabilities.

TIS-B position reports are SSR based and should be expected to be less accurate than either ADS-B direct or ADS-R.

There are many places where gliders and gliders, or towplanes or GA aircraft that might have 1090ES In will be together that won't have TIS-B service coverage. Think of lots of GA airports that glider operations may tow out of or gliders may land at. And many busy airports I can think of where you lose SSR coverage as you decent to pattern height, they concern me as pilots may stop seeing TIS-B targets and be lulled into assurance the target is not longer a threat. Ditto for aircraft without properly configured ADS-B Out that are piggybacking on nearby aircraft to cause TIS-B (and ADS-R) message broadcasts, things going quiet on the traffic displays does no mean there is no traffic.

2) It sounds like with the TN72 GPS source, I will not be compliant if wanting to enter Class B, C, and a few other little used airspace. My question is this... If equipped with a TN72 GPS source, do you think that ATC will allow temporary access to Class B and C... such a for passing through their airspace? That was ONE reason for equipping with a transponder in the past. I have no intention of OPERATING in Class B and C so as to use full ATC services. Also, do you think that controllers for restricted airspace MIGHT allow transiting that airspace without fully compliant ADS-B out?

Don't know, talk to your local ATC folks.

If ATC uniformly will disallow temporary transiting of Class B, C and restricted airspace unless equipping with a fully compliant GPS source (i.e. TN70), then there is VERY LITTLE REASON TO EQUIP WITH A TN72.

Again I talk to your local ATC folks. I would not want to ask any national authorities about uniform ATC treatment if any special situation. Work out things locally and use that to guide what you do.

I see small potential justification for equipping with a TN72:

A) visibility to all ADS-B official aircraft directly without rebroadcast (ADS-R) which means they can see me in the pattern a low altitude.

But you still won't be seen by aircraft in those situations. that only have UAT In. You *need* ADS-R ground service coverage for that.

B) Potenially, a TN72 will also give me an alternative to a Satellite tracker if Flight Aware or Aerion makes tracking of ADS-B aircraft less expensive than the current vendors (Spot and Garmin Inreach).

The current Garmin InReach tracker is relatively low cost and already more capable (esp. two way messaging and reliable operation on the ground (as long as you have line of sight of satellites) than what ADS-B will be able to do. Having ADS-B Out is further information, that might be be very useful in a SAR situation. I would certainly include that in discussions with club members, FBOs, written down as part of your emergency information/plan that you have (everybody has one right?) make sure it is noted on your NOAA ELT/PLB registration, SPOT or InReach tracker registration, etc. But I'd not be upgrading to 1090ES Out for SAR reasons--I'd buy a Garmin InReach first if I did not already have one.

And the FAA/SAR organizations today can get to ADS-B flight traces, so if an ADS-B out equipped glider should go missing it's important to make sure SAR groups are aware that it was so equipped.

comments...

Walt Rogers WX

You may also want to have 109ES Out to provide better long-term visibility via PowerFLARM when buddy flying.

Many aircraft are going to equip with ADS-B Out by 2020. I'm anecdotally seeing a lot of GA aircraft equip with ADS-B In, with most new potable and fixed systems being dual-link receive. Given all that if you fly near busy GA aircraft areas I expect equipping with ADS-B Out to be interesting to consider, fast jets and airliners can see you today via TCAS, in all airspace at all times. 1090ES Out starts also providing that "all airspace and all time" capability to GA aircraft as they equip with (1090ES or dual-link) ADS-B In.