Now the other way around. As you know you can obtain veriouse Free sceneries for veriouse sims from RC-sim and many other sites.
You can also obtain equirectangular images from Flick.com. These guys take pano as a hobbie.

Anyway, If you wish to have those sceneries in the sim that you own. You just need to convert the images into the formate that
your sim will allow you do. Example, in Preflight you can load as sphere mapping or skybox.

FMS and Heli-x can use SKYBOXES of course.

Here is an example of how I converted one of the Reflex's pano (equirectangular)
The Reflex's images comes as 8160x3060...it's incomplete. 1000 pixel of the bottom had been cropped off.
You don't see the missing portion becuase it's the shot under the camera's pod..and it is neglectable.
However you still need to return the image back into 2:1 ratio or 360x180, (do not resize the image.....add back by increasing the canvas size)
otherwise your pano will get displayed funkie or incorrectly.

You must do this even if you wish to use the pano for aerofly or G3/4


To get rid of the white circle of the missing shot . i simply just inverted the original pano...shrink the hiegth and layer it to
the bottom of the equirectangular. This will give me what some people call...sterographics or mini planets when converted into a skybox.
I use GIMP...gimp is a FREEWARE.
I also use Cube the Sphere for SKYBOX conversion, this too was a FREEWARE.