ADS-B, replacing transponder, compatibility with existing Skywatch system (repost!)

[gsengle]

Ok, reposting this thread since it got clobbered in the outage:

 

My King transponder is dying, so I need to go with a solution that solves ADS-B out.

 

1)  I will get either the Garmin/Avdyne or Trig option for a mode S/ADS-B out 1090mhz transponder...  I'm leaning toward the trig TT31, given the reviews I've read and that it is a slide in replacement for my King.  I already have a 530w.

 

2)  At a later date I would (maybe) add certified ADS-B in, but in the mean time, I will use a portable solution.  My question here is, I have a skywatch system already - any idea if the traffic from ADS-B can coexist with / augment the skywatch input in a reasonable way displayed on the 530?  Thoughts?  Maybe Trig will come out with an ADS-B in only solution cheaper than Garmin's GDL 88 (I dont need UAT out)?  Thoughts?

 

thanks,

Greg

 

[Piloto]

Like any conventional TCAS system your Skywatch will still be able to detect ADS-B 1090MHz traffic. All ADS-B 1090MHz transponders are required to to be Mode C/S compatible like the old ones. What Skywatch will not detect are the UAT 978 Mhz transponders but that is irrelevant because those planes will still have the old Mode C transponders. ADS-B out data format does not have the speed and data to issue RAs for TCAS II systems. Unlike TCAS II plane to plane two way link ADS-B out is a one way broadcast link unable to resolve a conflict between two or more converging planes. You do not need to upgrade your Skywatch beyond 2020 to detect traffic as it do it now. However ADS-B provides traffic vector data. But if there is no upgrade for the Garmin 530 to show the vector then there is no benefit to upgrade the Skywatch to ADS-B. Keep your Skywatch, is a good product.

José

[OR75]

Question:

 

if one chose to have the UAT (978MHz) ADS-B out as a way to comply rather than the mode S, will he have to keep the current Mode C transponder ?

 

To be clear, I am wondering whether in some cases the need for so called Pitot-Static check can be gone  

[Alan Fox]

It is my understanding that the ADSb boxes will work independently of the ships transponder ,  The ADSb hardware will transmit and recieve the mode s data independently ....It is also my understanding that the ModeS transponders with extended squitter will be capable of transmitting ADSb data without additional hardware , Please correct me if I am mistaken.... 

[Piloto]

You will still need to carry your current Mode C transponder to be visible by TCAS aircraft.

The static check will still be required to insure your transponder transmitted altitude is on the same reference as traffic around.

Mode S transponder need to be connected to a GPS source such as a GNS 530 to be able to transmit ADS-B parameters. Also a barometric altitude source such as the traditional altitude encoder or an air data source.

José

[OR75]

does not male sense completely.

ADS-B does require a WAAS GPS positioning. why bother with altimeters and encoders ?

[Piloto]

does not male sense completely.

ADS-B does require a WAAS GPS positioning. why bother with altimeters and encoders ?

You have a good point. Specially at high altitude were GPS altitude can provide better resolution than a barometric source. The problem is that WAAS coverage covers only the US and that GPS is controlled by the USA. Can you imagine the FAA defining satellite US approaches using Glonass Russian satellites. Because nobody has control over the atmosphere it is more acceptable by the world community. Using the atmospheric pressure is not that bad since all the aircraft in an area will be under the same reference. Where GPS altitude is a must is for ground related events such as approaches and terrain avoidance.

José

[carusoam]

It seems that we selected a standard to operate from that is globally available and usable. As long as we set it to 29.92", right?

Keeps us from running into other objects at altitude...

-a-