Originally Posted by
DXjr
In such cases, the flight numbers, as filed with ATC, are stub amended, as we like to call it.
Let's assume that marketing has made DL1933 operate LGA-ATL-DAB, with LGA-ATL as an MD-80, and ATL-DAB as a DC-9.
DL1933 LGA-ATL, the filed ATC callsign will be DAL1933.
DL 1933 ATL-DAB, the filed ATC callsign will be DAL933B.
The actual callsign will be something similar based on whether it has been used that day or not.