That would be a VFR flight, meaning one that is conducted in accordance with visual flight rules. The pilot would request IFR clearance. We would identify the flight, ask the pilot what they want to do and give them clearance based on our capacity at that specific time, depending on the flights already in the area. In other words, if an aircraft departing from Kingston requested IFR clearance, we would check the other flights and, according to our capacity, give the flight IFR clearance.
As for Aeroflot and flights that use an air navigation service provider, 99.99% have already filed their flight plans.