Unable to see private aircraft

6 years 4 months ago - 6 years 4 months ago #251 by stephanielingwood
Hi all,

First off, thanks for providing this API! I've been trying to get data for some aircraft associated with a flying club, and those aircraft have yet to show up in the OpenSky data. They all have ADS-Bs, they're flying in an area where there appears to be good coverage, and yet...nothing. (Attached is a pic showing current coverage in my area, and a flight that I knew was in the air at the same time.) Here's a sample query I've used:

https://USERNAME:PASSWORD@opensky-network.org/api/states/all?icao24=a6c237

I'm stumped. Is my query bad, is this a limitation of the data, or do I need to do something to allow data to be returned for our general aviation aircraft?

Thanks,
Stephanie
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6 years 4 months ago - 6 years 4 months ago #252 by strohmeier
Hey!

Where do you get that second screenshot from or rather when and where are you looking for that aircraft exactly? I haven't found any ADS-B data received from it in October, but it is certainly displayed. See for example the attached screenshot from July (or here in large: www.dropbox.com/s/uppj6px0v84rb0r/Screen...%2018.22.51.png?dl=0).

If it's generally flying fairly low (here around 5000ft) then even in areas where there is nominally coverage, it might not be displayed much. OpenSky displays general aviation just as commercial aircraft, but of course many of the former tend to fly lower and thus are less noticeable in many areas.
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6 years 4 months ago - 6 years 4 months ago #253 by stephanielingwood
Thanks for the quick reply!

The second screenshot was from FlightAware - I was watching the aircraft on their site to know when I should (hopefully) be getting data returned from OpenSky. A few minutes before that screenshot, FlightAware had them at 5,000' at 47.2461, -123.0394 (timestamp 1508472828).

Here's another of our GA aircraft I've been watching tonight -
https://username:password@opensky-network.org/api/states/all?time=1508039895&icao24=ad8295

FlightAware had them at 6,000 ft at 48.6367, -122.5400 for timestamp 1508039895. That's an interesting thought about aircraft being less noticeable at lover altitudes - I didn't know that about ADS-B receivers. You are correct in that a lot of these aircraft are flying at 5,000 - 6,000 feet (4,500 - 5,500 feet above ground level), so maybe that's what's happening. FWIW, here's the query for all our airplanes; I have yet to get data on any of them (but then, maybe there's data when I wasn't looking?).

https://username:password@opensky-network.org/api/states/all?icao24=a1d2c8&icao24=a5eb18&icao24=a6c237&icao24=ad4328&icao24=a5374f&icao24=ad8295&icao24=aa38f3&icao24=a9dea0&icao24=aa33d5&icao24=a221d4&icao24=adbcd8

So, sounds like I may be running into limitations with the network's ADS-B reception, vs. having, say, an incorrectly formatted API call?

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6 years 4 months ago #254 by strohmeier
I just checked for all your aircraft, and we definitely get data somewhat regularly. Yes, ADS-B is Line of Sight communication and thus messages aren't received when there is something blocking the path between aircraft and receiver(s), generally speaking. When aircraft fly lower that is naturally much more likely to happen and to get good low altitude coverage in an area much more sensors are required. You could put one up in your area and feed it to OpenSky! :)

When aircraft are close to a receiver, they can be seen on OpenSky, even when they are flying low. For example, on October 4, 17:57 UTC, you can see N2365C/a221d4 at around 1000ft in the OpenSky Explorer. Consequently, an API call for that aircraft at that time gives you back the last state vector: opensky-network.org/api/states/all?time=...139829&icao24=a221d4
The following user(s) said Thank You: stephanielingwood

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6 years 4 months ago #255 by stephanielingwood
Thanks for checking - that helps to know that they're showing up in the data, albeit occasionally. I'll have to look into putting a receiver up at our house and/or at the hangar; it'd be nice to be able to contribute to the dataset. In the meantime, thanks for all the help!

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