Need Help

I am new to alice, and ai am working on a plane thing. I need the ground to be collidable so when my biplane hits it it crashes (heres the catch: it cannot be the propeller colliding, only wings and body).

the easiest option is to set up an If/Else that returns an explosion or nothing based on the object (plane wings/body) distance above the ground. Use an a>b and a<=b function, drop in planes body distance above ground into a and put the distance you want in b. There are probably more sophisticated ways to do this...but this is how I would do it.