Cockpit or FPV view is only available on Simulator airports that are fully rendered in 3D.

Many simulators, like Phoenix or Reflex feature predominantly 2D airfields also called "Photo fields".

In this your viewpoint is actually fixed within the center of a large cylinder or sphere with the photo or image of the actual airfield virtually projected onto the sphere or cylinder.

Moving the viewport destroys the illusion of flying in a photo field, since it permits you to see that the viewpoint is moving around inside this large object.

The advantage of this technique is that the computer has less work to do versus a fully rendered airfield.

Never-the-less things like depth/collision buffer are required so that the simulator can give the illusion of a plane crashing into an object in the photo.



3D ( or what Aerofly now calls "4D") airfields render a complete 3D "world" so to speak much like an advanced video game.

This is far more processor and GPU intensive, but permits the viewpoint to be moved with the virtual 3D objects appearing correctly to the pilot.

3D rendering requires far more work for the programming team as a virtual airfield world has to be built up, much like a designer would construct an entire town plane or city in 3D ( yes I'm simplifying... ).

IMHO 3D is far far better than photo fields. The former can have a bit of a "video game" visual feel to it, given the amount of rendering possible, but objects can behave in a more realistic manner... e.g. winds can throw leaves across the runway, trees sway, etc.

Some Sims provide both ( e.g. Aerofly & Realflight ) to give the end user choice while scaling to slower machines...

Phoenix is primarily a 2D "Photo field" sim, so no cockpit or FPV views, nor "walking" your vantage point around.