This question is about a nuance of language that would probably go unnoticed to any casual reader, and in my opinion you could use either one without causing any misunderstanding (on a side note, I agree with @Mick that trips originate in a region and not from a region).
If you want to be very precise, the past participle traditionally means that the action is in a steady state; in this case departed conveys the meaning that the action of departure has been completed and that there is some separation between the object and the point of origin. On the other hand, the present participle departing means that the action is still ongoing.
For example I would consider an airplane during take-off as still "departing" if it has not yet left the runway, and "departed" the instant it's airborne. On the other hand, the flight itself, as a regular scheduled service, is never described as "departed" because it does not move: I would always describe it as "departing", like this:
- The flight departing from London at 10.40 arrives in Moscow at 17.25 local time.
- The plane to Moscow departed from London at 10.40 and arrived at 17.25 local time.
In your specific case, following this line of reasoning, since the trip itself does not move, and there is no separation - rather the contrary, it's like a line connecting two dots - I would always describe it as "departing".