FlightAware Discussions

Nice bit of tropo over the UK and Europe today

Here’s my timelapse of the same aircraft. I lost it at a strange place, I’d have expected to have seen it a lot further south and east of that location so I wonder if it was transmitting erroneous data.

It looks like VDA3621 just followed the usual flight path (dashed line) but the location data was shifted significantly.
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I too have some massive range spikes.

Well massive for me anyway, I live in a hole…

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The one on the far left is exactly the same as mine.

But how does it explain that the distance is calculated so bad?

The whole flight path is way outside my regular range, but i still got this signal.

If it was reported by MLAT then it was real, if nor then probably the ADSB Tx is reporting incorrectly with a very large positional offset.

wouldn’t than not be the ADS-B message count “0”?


Look at the NACp value. EPU (“estimated position uncertainty”) >= 18.52km (10NM) is the worst category and basically means that the transponder has no confidence in the position it’s transmitiing. A correctly operating transponder/GPS would be reporting a value < 0.1NM.


This value is shown on my map for all MLAT reported aircraft here

Those are synthesized mlat positions, not transponder-reported positions. The mlat server does not claim any sort of accuracy, so that EPU is appropriate.

“The whole flight path is way outside my regular range, but i still got this signal”
The erroneous projected flight path is indeed far away from you but the real flight path passes over the southern part of Mainz and that should be in your reception range for quite some time.

OK, that makes sense. But why are the others in UK for example get this flight? Do we see somewhere the real path?

The usual flight path is the dashed line.

I’ve offset the flight path so the landing is somewhere near Munich. (please ignore the plane position, ugly hack in the javascript)

Got it.
My range goes also to north east, so i have received it also with the unusual path north of Frankfurt

Yes, now it makes sense. Thanks for clarifying

That’s much better and it ties up nicely with my track and where I lost it.

Hi everyone,

I saw these posts tonight and had a look too- saw a couple of aircraft over 340 miles away- just north of Onsabruck in Germany. Pretty amazing.

I used to do microwave planning in the high UHF/ low microwave bands when I was a young engineer. I would dealy love to have enough surplus cash and time to test a space diveristy setup for my Flightware site. It strikes me that a pair of antennas spaced by say 5 metres and digitally combined would be highly effective on days like this…

Kind Regards,


Is there something going on today?

This morning at ~5 I had all GND stations (as shown on planefinder) in Denmark.

And this while I was at work. My usual range is ~240 nmi.
3 new “spikes”, marked with an arrow;


That’s my normal indication of decent conditions, I get a handful of Danish ground stations drop in.

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