Missing MLAT track pieces

Since some time (couple of days ??) it seems that (mainly) MLAT tracks are failing somehow.

The screenshot shows an example of what i see on most MLAT tracks.
When the “track” fails, i can see that there is signal, but no MLAT track is beeing displayd.

Yesterday I did a complete new reinstall of my RPi3 with the PiaWare 3.5.1 image, but still the same issue.
I here from other guys they “see” the same problem.

Is this a problem with the FA servers, of a problem with my receiver ?

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Do you have a timestamp to go with the screenshot?

The screenshot was taken at 07:40 (05:40 GMT)


I don’t see the gaps in the mlat positions we generated, but your receiver (not sure which of your receivers you were looking at specifically, but they all show the same sort of thing) did not participate continuously.

The cause is probably that you are in a very densely covered area and so the mlat server picks only a random subset of receivers for each aircraft. The receivers are re-selected periodically. There is a grace period where you will continue to receive results even after being deselected but with enough receivers in an area you can go without being selected for long enough that the results stop until you’re reselected.

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Thanks for the explanation obj.
I can’t rember seeing this behavior before, and i’m not really “happy” with it.
Sofar MLAT (tracks) was working rather nicely here, but now with these “interrputed MLAT-results”, flight tracks become really weird to look at.

Basiclly we (Netherlands) are now being “punished” for supplying TO MANY feeds.
Shutting down 2 or 3 of my own receivers won’t make a diffrence i guess ?

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It is unfortunate but processing data from every receiver for every aircraft is not practical or useful in busy regions.

I’ll see if I can increase the grace period; it was turned down after we had some load problems with forwarding results back to piaware, but those problems have been resolved.

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Don’t shut them down, there are other places to send your data to that will appreciate it… :slight_smile:


Did you change the “Grace Periode” ??
Today MLAT tracks show a lot better then the last days.
Or is this because traffic is less then before ?

I increased the grace period from 1 minute to 3 minutes on the 28th.