Originally Posted by
hikouki
I'm just curious if the flight number is modified when the first "leg" is delayed? There can't be two DL199's up in the air at the same time?
Dispatch will just modify the ATC callsign on the ICAO flight plan that's filed (ie DAL199A "alpha" for the SEA-ICN flight, or the domestic inbound leg if they catch it before it departs. This would be transparent to the passenger from a RES / FLIFO perspective. Only ATC would see it.