Set/Edit a reference location...
... and get a list of nearby aircraft's details
... including distance from location

See Matthias Schäfer, Martin Strohmeier, Vincent Lenders, Ivan Martinovic and Matthias Wilhelm.
"Bringing Up OpenSky: A Large-scale ADS-B Sensor Network for Research".
In Proceedings of the 13th IEEE/ACM International Symposium on Information Processing in Sensor Networks (IPSN), pages 83-94, April 2014.