One personal item and one bag are acceptable as hand-carry luggage on domestic flights. The bag cannot surpass 40 pounds with a linear measurement -- length + width + height -- of no more than 45 inches. It must be stored in the overhead compartment or under the seat in front of you without any obstruction.
The TSA´s 3-1-1 rule pertains to liquids and gels. The liquid or gel must be three ounces or less, must be in a one-quart small containers, then in a clear plastic zip-lock bag. This bag is separately scanned and viewed by the security agent. The agency only allows one hand-carry bag per person.
Items generating possible harm are restricted from the cabin. Sharp objects, cigarette lighters, batteries, sporting equipment and tools are some of the items prohibited. Check with the airline carrier to establish carry-on policies and question if the item is acceptable as checked luggage.
Items purchased within the secure area of the airport are permitted on-board. This includes food to go, cosmetics, perfumes and liquids of any size. Prescription medicines, baby formula and insulin in quantities greater than three ounces are allowed as long as the TSA is advised at the security check point.
Restrictions may differ for hand-carry luggage on domestic flights versus an overseas airport or international flights. It is advisable to contact the airline directly for updated information.
