FlightAware Discussions

Aircraft.json - How to determine the number of aircraft?

I would like to fetch a few high level values from the aircraft.json from dump1090-fa/data/aircraft.json.

Getting the data and going through the values is not the problem. What is confusing me is that I have roughly 30% more records in “aircraft” than what the webpage under dump1090-fa is showing as “Total Aircraft”.

While the webpage tells me there are some 28 aircraft (including the list in the table below), I do get some 38 aircraft records in the .json. I have gone through the data and also looked at all the various fields in this description of the data: https://gitlab.rhrk.uni-kl.de/s_schumb/dump1090/blob/master/README-json.md
But I can’t find the criteria as to when dump1090-fa is “counting” a record and when not. Is there a simple rule to that?

Well you could look at the javascript code.

Pretty sure it’s seen < 60 or something along those lines.

I have tried to figure out how that is done by looking at the javascript. But I’m not that fluent in javascript, and I couldn’t figure out where and how it is filtering the records.

Why do you care anyhow?

I’m pretty sure about the (seen < 60) condition.
(seen < 30) or even less might be a better representation of the planes you’re currently receiving.

So it’s really up to your interpretation.

It’s not THAT important, but I was just wondering why certain aircraft are filtered out. So when I display the number of aircraft on my dashboard, I’d like to have the same value for consistency reasons.

58 seconds.

I’m somewhat familiar with the code after making a fork of the UI.

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Oh, that is seconds. I somehow assumed wrongly that was the number of aircraft.

Awesome. Thank you very much!! That made my day.

An aircraft can remain in the JSON file for up to 300 seconds after it was last seen.

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In the JSON file, the seen_pos - how long ago (in seconds before “now”) the position was last updated, has a maximum value of 70 seconds.

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