Callsign CSA is Czech Airlines
WHAT AIRLINE IS CSA?
CSA is the ICAO three-letter callsign prefix for Czech Airlines. When a radio scanner, flight tracker or radar scope shows a flight like CSA123 or CSA45XY overhead, that's a Czech Airlines aircraft talking to air traffic control.
Spot one yourself: open the live scope, enter your postcode, and tap any blip whose callsign starts with CSA for its type, registration, route and photo.