Federal Aviation Regulations explained - The confusing and sometimes constricting airline regulations regarding what can and cannot be carried on an airplane are constantly changing. They are updated as new methods of terrorism come to light and as new electronic devices are manufactured. Fortunately, the United States and Europe have similar regulations on what can and cannot be carried on board a commercial airline flight. European security checkpoints are known to be more exacting and travellers should plan for extra time so they do not miss their flight. The United States and Europe both allow gels and liquids in 3 ounce or smaller clear containers to be placed in plastic bags. These items must be shown to the security officer at the checkpoint and declared. Other liquids that can be carried on include baby formula, eye drops, and medications. All of these items require extra screening which means more time at the security checkpoint.