In the United States and Canada, a CPAP machine is considered a medical device and does not count toward your standard carry-on limit. Under the Americans with Disabilities Act (ADA) and FAA regulations, passengers are allowed to bring their CPAP in its own carrying case in addition to their one carry-on bag and one personal item. However, it is essential to ensure that the bag contains only the medical equipment and its accessories (mask, tubing, power cord); if you pack clothes or books in the same bag, an airline could technically count it as a regular carry-on. When going through security, you may be asked to remove the main machine from its case for X-ray screening, but you can keep it in a clear plastic bag to maintain hygiene. It is also wise to carry a copy of your prescription or a manufacturer's "FAA Compliance Letter" just in case.