You most probably had an Out Of Memory crash (OOM).
Since FSX is a 32bist application, the max amount of memory it can utilize is 4 GB, regardless how much RAM You have installed.
The 4 GB is a combination of work RAM and Video RAM.
FSX is also sloppy in it´s ability to free up VAS, so on longer flights VAS will gradually be eaten up, especially when flying over (Even at 36.000 ft) other addon sceneries, like airports.
Photo realistic sceneries are loaded in FSX regardless if they exist on the other side of the globe. So if You got some US photoreal scenery, then this will also eat up VAS when You start from Copenhagen.
I also had an OOM yesterday, testing the EKCH scenery with the PMDG 737 NGX.
Please refer to this post I made:
viewtopic.php?f=28&t=6941
You should cut down Autogen, Water settings, Traffic and keep away from high-res textures to be on the safe side.
Also in the Fly Tampa scenery configurator You might need to remove some of the graphical enhancements.
The PMDG aircraft addons in general are very VAS hungry, so You might not have an issue with other addons.
It´s really time for developers of both aircraft and scenery addons to make considerations regarding VAS usage.
Finn Jacobsen