Hi, welcome to the forum. Collisions can be real confusing. You have to break it down. In your jet actor or character bp, look at what all is there, and then go to the collision and see what is ticked. Ignore? Overlap? or Block?
Ignore equals no acknowledgement of other things you pass through.
Overlap means it can pass through a mesh and trigger a response (and make sure generate overlap events is ticked). Like a ghost but it detects when it touches.
Block means it can’t pass through. This would be like a solid object not being able to pass through a wall.
As this is a jet simulator you probably want the jet to explode on impact with the ground. Sometimes you can create a custom collision channel in project settings that can make life easier.