Well, I dunno about that... I'm in Canada, so it may differ in the states. But here anyhow, as far as I know, it must be carried on board at all times, and not only that, but must be within the pilot in command's reach. It must be on board in order for the C of A to be valid for each flight. The only thing we don't ALWAYS have to have on board is the Journey Log... we don't have to carry the Journey Log as long as we aren't touching down at another airport, or as long as we are staying within 25NM of our point of departure. So hopefully that can clear up the Canadian side of things, as I am not aware of any small aircraft not having to carry it on board. However, as an after thought, perhaps aircraft like an ultra-light, do not have to carry it on board, as perhaps, there simply is no place to carry it? Perhaps an Ultra light pilot can clear that one up.