Newbie: What happens to live tracking when flight delayed?


I wanted to track EZY5378 dep Cologne for Lon Gatwick at around 20.30CET on 30/12.14. The departure was given as 2 hours late which I tracked to the incoming flight EZY5377. The only tracking info I can find for flight EZY5378 is a departure at 1400hrs next day. LGW live flight boards confirm the approximate late landing time. I assume the plane is in the air confirmed by the local live flight boards, but not tracked against its original flight number by Flightaware.

I’m puzzled as to how this all works. I assume the squawk is linked to the flight number somehow and delayed flights must mean a revised flight plan and squawk code (?), so how does the Flightaware tracking data keep synchronisation with a delayed flight such as this example or do delays cause exceptions and Flightaware tracking fails? Do delayed flights get a revised flight number which is not the same as the original, but the airport boards still work to the original number?

Sorry for a newbie question.


What day was the flight on that you were attempting to track?