An aircraft on a flight may not maintain the same identifier/callsign for the entirety of that one flight. Famously, President Richard Nixon departed Washingto

An aircraft on a flight may not maintain the same identifier/callsign for the entirety of that one flight. Famously, President Richard Nixon departed Washington DC on Air Force One bound for California. In flight over Missouri, his resignation took effect and Gerald Ford was sworn in as President. When that happened, the callsign of the flight changed to SAM 2700. https://en.wikipedia.org/wiki/Air_Force_One#SAM_27000 https://en.wikipedia.org/wiki/Air_Force_One#SAM_27000