Collisions on imported objects

Hi. I have two objects that have been imported, a landscape, and an aeroplane. For some reason, I can not get them to collide. I have a tried using a mesh collider, and a rigidbody, but the plane just flies through it. Missile collide with the landscape, but not the plane. To get the missiles to collide, I had to add a mesh collider to each of the 2 parts of the landscape, but the plane has around a hundred parts, but adding one to all of them doesn't work. Any help?

well… having imported a file it came into 2 parts one of which was a mesh, if you haven’t already tried make a mesh collider and drag the mesh onto it? this was with a .fbx - am I missing something? it works for me

Don't use mesh colliders for moving objects, use primitive colliders. Also you need to read the docs:

check `Generate Colliders` in the mesh importer in the project.