FlightAware Discussions

Hourly Received Reports = Flight Density?

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I’ve been looking at Hourly Received Reports thinking the variation in blue depth was correlated to density (or frequency over time) of flights. But as a Ham radio operator, I know that reception is a function of propagation.

To what extent can I interpret this plot as density of flights? For instance, were there more flights in my reception “window” (fixed antenna location) 11am 30Dec or was my reception just that much better then?

Bret/N4SRN

Hover your mouse over the squares for the individual hourly values. You see aircraft and positions for each hour.

But 11-Noon 30 Dec, were there 221 aircraft known to be within my reception zone (as I saw on mouse hover), or did I just receive signals from 221 of 300 aircraft? Still learning this PiAware stuff - lots there!

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Bret/N4SRN

Not at all, really. It’s measuring position reports uploaded to FlightAware which is, at best, only loosely correlated with density. The rate of uploaded position reports for an aircraft depends a lot on what the aircraft is doing.

Possibly the unique aircraft counts are closer to what you want - they count unique aircraft seen within each time bucket. But I suspect that you will need to go back to the raw data (or at least the json output) and analyze it yourself to get useful numbers for density.

ADS-B data is fairly tricky to measure because there are so many invisible variables. Aside from changes in the RF environment, you also get changes from the day of the week, weather affecting flight patterns, changes in flight schedules, airport/runway closures, a helicopter that happened to spend a lot of time loitering nearby, avionics testing of an aircraft on the ground, an aerial survey flight that happened to be mapping overhead on that day, etc etc.

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Gotcha, thanks. But it’s still fun stuff!