Is this Traffic Advisory genuine?

[jdubner]

The aircraft causing a Traffic Advisory is 400 feet above me at my 5 O'clock position and 5 miles. The orange vector arrow indicates he'll move about 24 NM in one minute so he'll close the 5 NM gap in about 15 seconds.

Is this to be believed? Or is my SV-ADSB-472 confused?

 

[airguy]

I've seen that before, I believe it's an artifact of the groundstation losing contact with that traffic target momentarily and transmitting bad data up to you. The traffic would have to be travelling about Mach 1.4 or thereabouts for that track to be factual, which is not impossible at your altitude but is highly unlikely.

 

[jdubner]

Hmmmm, that makes sense (sort of). Thanks for your reply.

I hadn't considered groundstation involvement as my SV-ADSB-472 is a dual-band receiver and theoretically has no need for ground station retransmission EXCEPT for radar-only aircraft. This implies the F-15's weren't using ADS-B.

BTW, 24 NM in one minute is about Mach 2.4 -- even more unbelievable at 4000 MSL.

 

[Dynon]

The truth is out there.

 

[jdubner]

The truth is out there.

That's your best answer?

My question is serious. I would like to know why the SV-ADSB-472's Traffic Advisory feature is broken (and what can be done about it). Perhaps you would be kind enough to put this on your list of SkyView defects.

 

[airguy]

It's not a Skyview defect, it's an ATC artifact, as I understand it. I'll let Dynon fill in the details of exactly how but it's been seen and addressed before.

 

[Raymo]

As @airguy said. If you want it fixed, you'll need to talk to the FAA.

 

[jdubner]

I'd like to hear what Dynon has to say rather than having customers speak for it.

Just because it's an ATC artifact doesn't let Dynon off the hook. The FAA doesn't control my SkyView. When a 24-mile vector is displayed on my screen, it's a Dynon defect plain and simple.

There's a concept called "Contract Programming" in which the input conditions to a function are error checked or at least sanity checked before being processed. Is Mach 2.4 correct or expected? One implementation would limit TA vectors to 8 or 10 miles with a question mark instead of an arrowhead. I'm sure Dynon software engineers can come up with something if this is elevated to their attention.