To avoid checked baggage fees and the risk of an airline misplacing your luggage, it's smart, when you're packing for a flight, to limit yourself to your airline's carry-on allowance. Generally, that means one bag for the plane's overhead compartment and another so-called "personal item" (a purse, tote bag, backpack, briefcase, or teensy rolling suitcase) that will fit under the seat in front of yours.
It often happens, however, that overhead compartment space runs out before every passenger has boarded the plane. In that case, you could be obliged to check your larger carry-on at the gate, leaving you with just your personal item.
There won't be a fee, but your bag will, despite your best efforts, be subject to the vicissitudes and inconveniences of checked luggage—getting lost, getting sent to parts unknown without you, getting delayed at baggage claim, and, obviously, getting separated from you for the duration of the flight (at least).
For these reasons, you should always stash certain travel must-haves in your onboard personal item in case you can't get your hands on the rest of your stuff for a while. These are the belongings that prove who you are, help you communicate and pay for stuff, and maintain your health and safety—the sort of essentials you'll want to keep within reach.
So whether you plan to check a suitcase or go carry-on only, here are the eight things you should always pack in a bag that will fit under an airplane seat:
• Your ID and other important travel documents. This includes your passport or, if you're flying domestically, valid state-issued photo identification, as well as any visas you've had to acquire and any other documents you've printed out to make your life easier (itinerary, contact info, and so on).
• Your money. You were probably already planning to keep your cash and credit cards close by, but in case you were thinking of slipping your wallet into a zippered pocket on your roll-aboard suitcase or something like that, don't.
• Your phone and charger. The former is easy to remember, seeing as how we all seem to clutch our devices as if they were life-giving talismans. But don't forget the cord that gives the life-giver its life.
• Your other electronic devices. If you're traveling with a laptop, tablet, or other electronic gizmo, keep it with you to minimize the likelihood of loss, damage, or theft. These doodads will need their chargers, too.
• Your medications. Any daily prescriptions you take are a must. It's also wise to pack some over-the-counter pain relievers (such as aspirin or ibuprofen) and meds for allergies and motion sickness if you're susceptible.
• Your glasses or contact lenses. See also: reading glasses, if you need them.
• A small toiletries kit. If your flight is very long or if you get stranded somewhere, a travel-size toothbrush and one of those tiny deodorants will go a long way toward keeping your feral side in check.
• Headphones. Airlines don't always provide them anymore, and, besides, the quality of the freebies is usually subpar.
If there's room left over in the bag for a change of clothes, you might want to squeeze those in there, too. But remember: You've still got to save space for your trail mix and whatever James Patterson bestseller you settle for at the airport's Hudson News.