An inexperienced flyer could lose a plane fairly easily, but as long as you stay on top of it and know what direction you're headed, it's easy to keep track of your plane. Also, when you're dealing with certified AMA fields, only a certain number of people are allowed to fly at the same time. I know our field is only allowed to have five planes up at one time, so you have a very slim chance of losing your plane but there's still that chance.
Since our field is in a more rural part of Michigan, there are a lot of tall trees and swampy areas around. Quite a few planes have gone down and not been found; always a sad thing to watch close to $1000 fall from the sky... But it sounds **** cool when it goes "CRUNCH!"