FlightAware Discussions

Number of Tracks seen

Can somebody enlighten me what information and help can be gathered from the number of tracks seen?
There seem to be no direct relation to the aircrafts seen. Today i’ve received two spikes which are not related to increased aircraft traffic.

I understand on a reboot or restart of dump that the number is going up because the tracks must be read again.
But this time i did not do anything, the device was running all the time.

Notice how the shape of the green graph is similar to the shape of the red graph.
The red graph is essentially noise, so … the variation in the green graph is mostly that same noise.

It might be useful to plot “unique tracks” - “tracks with single message”.

nb: while it is generally true that you’d expect to see more aircraft when you see more tracks, it’s not strictly true, since one is measuring the density of aircraft in your coverage while the other is measuring the rate that aircraft pass through your coverage. A change in average aircraft speed or a change in the distribution of aircraft can change the relationship between those.

Yes, it’s similar, but the overall of green is higher in relation to the red ones
So it’S not coming from the red ones only, seem to be a percentage.

But it still doesn’t give me a satisfying answer what to do with that information.

Data interpretation is left up to the reader :wink:

I can only interpret what i understand :wink:

Check up on what the number is:
https://github.com/flightaware/dump1090

Also note that there is an 5 minute rolling average added to that graph in my version of the graphs.

Just reduced it to 2 minutes rolling average, been meaning to change that for some time.

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From the JSON readme:

tracks: statistics on aircraft tracks. Each track represents a unique aircraft and persists for up to 5 minutes after the last message from the aircraft is heard. If messages from the same aircraft are subsequently heard after the 5 minute period, this will be counted as a new track.

Look at it as the number of aircraft coming into range per hour, whether that is newly arriving in your receiver range or coming out from behind an obstruction after a gap of at least 5 minutes.

It’s not necessarily a useful metric for assessing receiver performance since the figure changes so much with aircraft behaviour - a steady stream of aircraft arriving and landing that you can see continuously might show a similar number of tracks to only a few aircraft flying around and going in and out of coverage.

It’s a figure that is going to be fairly unique to your location and receiver set up, since things like obstructions will affect it quite a bit.

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