Monitoring airplane traffic with a RTL-SDR and dump_1090.
Get dump_1090 from https://github.com/antirez/dump1090
*20280190e86772;
CRC: e86772 (ok)
DF 4: Surveillance, Altitude Reply.
Flight Status : Normal, Airborne
DR : 5
UM : 0
Altitude : 1400 feet
ICAO Address : 4a3494
*a828080002010000000000bc4ae9;
CRC: bc4ae9 (ok)
DF 21: Comm-B, Identity Reply.
Flight Status : Normal, Airborne
DR : 5
UM : 0
Squawk : 1000
ICAO Address : 4a3494
Decode with https://github.com/junzis/pyModeS
+-Online aircraft [1] ('Ctrl+C' to exit, 'Enter' to lock one)------------------------------------------------------------------------------------------------------------------------------------------------------+
| icao call lat lon alt gs tas ias mach roc trk hdg live |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|43EA56 44.49394 26.05715 2375 172 179 0.28 3776 253.14 250.312 -931s
You can track airplanes by ICAO code at RadarBox24.
Another Windows-only option is https://www.virtualradarserver.co.uk/ .