Make a test and spin the world to any land based location. Now zoom in to max level. Zoom back out to another location. Do it 3 or 4 times and watch your VRAM filling up even before you are in your aircraft.
That happened yesterday to me. I will test this later today again. But I would like to see if this goes for everyone. If it does, it would be highly recommended to use the world as less as possible before a flight.