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bekolblockage
28th Jul 2017, 05:47
Not getting any bites on the ATC forum, so trying here.

Question for those who have implemented ADS-B fused with Radar in "complex" airspace.

In the rare case of a bad ADS-B track with good NUCp value being broadcast (lets say the track is offset consistently by 20NM) forming a separate track from the 'real' radar track, what procedures/guidance do your controllers have for;
1. Verifying which is the real track
2. Once confirmed that the ADS-B track is incorrect and assuming the pilot is unable to disable ADS-B, what actions taken against other traffic that are/will be in conflict with the rogue track?
Ignore it?
Watch STCA alerts go off and ignore them?
Pass traffic info to other aircraft in conflict with the false track and offer vectors to avoid, 'just in case'??

Would be interested to hear others experience.

Cheers
BB
404 Titan
29th Jul 2017, 01:47
You could ask us to change transponders. We have two independent systems on the AC bekol.
Plazbot
29th Jul 2017, 06:21
Gulf V seem to be the main offenders with multi tracks.
le Pingouin
29th Jul 2017, 06:23
ADS-B tracks being displaced aren't just rare, they're vanishingly so. I'm only aware of one such occurrence and that was outside radar coverage. There may have been others but it can't have been many.

As such we don't have any firm procedures but prudence would say treat it as real.
LeadSled
29th Jul 2017, 06:31
Folks,
I am intrigued that this could happen on a C-145/146 GPS derived position, or is this some thing that is applicable to FMCS (by whatever name) derived position being broadcast.
Any ideas, please?
Tootle pip!!
swh
29th Jul 2017, 08:22
On the 787 it was a software bug.
bekolblockage
3rd Aug 2017, 10:20
ADS-B tracks being displaced aren't just rare, they're vanishingly so. I'm only aware of one such occurrence and that was outside radar coverage. There may have been others but it can't have been many.

As such we don't have any firm procedures but prudence would say treat it as real.

Thanks Pingouin.
Rare but we still notice the occasional one in non-radar. Now that we are moving to fused ADS-B/MRT in the TMA, the issue of how to deal with that in congested airspace is difficult.
As you say, you'd be a brave person to ignore it but trying to dodge the traffic in our TMA would be just about impossible.
Can't tell them to turn it off.
Can't blacklist immediately.
Pull ADS-B from the SDP?
Hmmmm.

Thanks for the reply anyway.
Have a feeling we may have worked together in Melbourne many moons ago. (?)
le Pingouin
11th Aug 2017, 16:49
Can't you tell them to recycle the ADS-B or squit standby?