I just received a call from a friend who was flying JAX-ATL-LGA. He changed planes at Hartsfield. At JAX the AirTran folks told him he would have to check his oversized backpack. He left his laptop in the bag. You know the rest. Please don't do this. It take a few moments to remove your valuables from the checked bag to spare you the aggravation of dealing with the lost luggage folks, insurance, local constabulary, etc.