[IowaRV9Dreamer]

I have the equipment above, and I'm surprised by how much traffic I don't see displayed. Often it is displayed, but disappears.

Today was a good example, I was IFR at 6000 over Iowa (so no terrain) but in VMC. Approached called traffic 3 miles ahead, 2500 below, same direction. We finally found the traffic (a Stearman) and flew directly over. No traffic displayed on the map or on the dedicated traffic page.

Everything was operational, and all display filters text to. "Unrestricted".

I know this is TAS and not ADS-B but the traffic was certainly displayed on ATC's radar and I'm sure I was in a covered area. It was much later in the flight when I flew out of coverage and got the "Traffic Not Available" message.

Is there some configuration problem? I don't think I have an antenna issue bite anything is possible. I've never gotten a report that ATC can't read my code.

 

[bkthomps]

i'm guessing the stearman, *might* have mode c

not the best example for traffic

 

[Brantel]

It was not TAS.... What you have is the ability to recieve TIS and some call it TIS-A.

You must be within ~60NM radius of a station broadcasting TIS and the other traffic needs to be mode C or better (mode A for no altitude), seen by the radar and within 7NM of your aircraft and Less than 3500ft above and 3000ft below you.

TIS never was the best. TIS-B is much better!

 

[IowaRV9Dreamer]

a TISket a TASket

i'm guessing the stearman, *might* have mode c
not the best example for traffic

Good point in general Brian - but this Stearman has mode C for sure (he's my next door neighbor at our class C airport).

It was not TAS.... What you have is the ability to recieve TIS and some call it TIS-A.

You must be within ~60NM radius of a station broadcasting TIS and the other traffic needs to be mode C or better, seen by the radar and within 7NM of your aircraft and Less than 3500ft above and 3000ft below you.

TIS never was the best. TIS-B is much better!

Oops, sorry. Mind thought TIS and fingers typed TAS.

Is the ground system applying the filter that you describe? The Stearman was 2500 below me and << 7nm.

I'll look for a coverage map. I want TIS-B

 

[Dynon]

TIS-A is there to find traffic that can actually hit you, not show you every plane around you. It's a client/server relationship to a computer on the ground that is looking out for you and only sends you important targets. It's not a broadcast of all planes. It will look at a target 3 miles ahead, 2,500 feet away, not climbing or descending, and say "meh." It is actually programmed to not bother you with worthless info. So likely, it knew about the Stearman just fine, but it's rules say this plane isn't an issue.

TIS-B (ADS-B) may seem "better" but when you fly around Seattle or any other major area with it, you really just see a lot of planes that are far away and will never be a threat. It's fun, but you can hardly see a plane that is 3 miles away, much less the 15 that ADS-B will give you.

We get people sometimes asking why our ADS-B system doesn't show the airliner they could see right above them. Ask them how much higher the airliner was and they say "oh, maybe 20,000 feet, all I could see was a contrail.." There's no point in a traffic system showing you that.

As a final note, neither TIS-A nor the ADS-R part of TIS-B require a plane to have a transponder at all, much less a Mode S to see them. You can get sent primary returns if you are in a place with radar service. Every target ATC can see is something that can be sent to you if it is near you.

--Ian Jordan
Dynon Avionics

 

[IowaRV9Dreamer]

Thanks for the clarification Ian - I didn't know the TIS (or TIS-A) system did all that processing on the ground. I'm more familiar with TIS-B. I found an interesting reference here:

https://www.faa.gov/air_traffic/publications/atpubs/atbarc/03-2.htm

TIS-A is definately more of an alerting system than TIS-B.

I do get a lot of "false alarms" when taking off or landing - mostly from aircraft on the ground (regional jets usually).

 

[Thermos]

Not every FAA approach radar is TIS capable, you may sometimes be in an area where the secondary radar can't provide that service. AIM Section 4-5-6 describes TIS and shows which radars have it. Also, TIS won't show aircraft as intruders that don't have operating transponders.

Dave

 

[Brantel]

Not every FAA approach radar is TIS capable, you may sometimes be in an area where the secondary radar can't provide that service.

Dave

This is true and many that had it are now decommissioned or are scheduled to be. Several were to be decommissioned years ago but are still operating. KTRI for example...

 

[Brantel]

TIS-A is definately more of an alerting system than TIS-B.

Its pretty much up to the display maker to take the data and provide the alerts and filtering which seems to work great on the mainstream units at least on mine it does.

 

[Brantel]

TIS-B (ADS-B) may seem "better" but when you fly around Seattle or any other major area with it, you really just see a lot of planes that are far away and will never be a threat. It's fun, but you can hardly see a plane that is 3 miles away, much less the 15 that ADS-B will give you.

A good ADS-B display should give the pilot the ability to zoom in and out to cut the clutter. A dedicated traffic page also goes along way to help.

We get people sometimes asking why our ADS-B system doesn't show the airliner they could see right above them. Ask them how much higher the airliner was and they say "oh, maybe 20,000 feet, all I could see was a contrail.." There's no point in a traffic system showing you that.

A good ADS-B traffic display should give the pilot the ability to filter out targets based on altitude.

As a final note, neither TIS-A nor the ADS-R part of TIS-B require a plane to have a transponder at all, much less a Mode S to see them. You can get sent primary returns if you are in a place with radar service. Every target ATC can see is something that can be sent to you if it is near you.

--Ian Jordan
Dynon Avionics

I do not think the part about TIS-A is entirely correct based on this information straight off of the FAA's website:

"To be visible to the TIS client, the intruder aircraft must, at a minimum, have an operating transponder (Mode A, C or S). All altitude information provided by TIS from intruder aircraft is derived from Mode C reports, if appropriately equipped."


TIS-A is dead....we must all move on. It never really worked that great anyway.

 

[dmaib]

I have a new GRT Hxr with the Radenna Skyradar D2 dual band ADS-B receiver and I have the GTX-330 ES xpdr. I get the ADS-B traffic on the Hxr and I also still get the TIS-A traffic on my 430W display. I am in an area with good TIS and good ADS-B coverage. I notice fairly often that the TIS-A display on the 430W will show traffic that does not always appear on the ADS-B traffic display. Now I know why. For the time being, I am happy to have both.