collisions help plz!!

I am making a flying game and i cant make it so the plane (its in first person view right now, so the plane is the camera)to make the collisions with buildings and the ground work right... you can go thru the buildings and the ground(wich is a plane and a heightmap)... plz help!! :D

i cant get it to work!! pleez help me!
can u also do it without types?

Setting up collision detection involves using the Collisions command and assigning EntityType to the colliding entities. You probably want to set up sphere-to-polygon collision detection for the plane to scenery.

And make sure to call UpdateWorld every frame since that command is when collisions are handled.