Plenty can go wrong over the course of your travels. Flight delays and lost luggage are common issues, but even if everything goes right, you still might find that you're underprepared for your trip. Check out our list of 20 crucial carry-on items that you should ALWAYS remember to pack, you know, just in case.

Extra Headphones
1. Extra Headphones

They don't even have to be GOOD headphones. But just imagine listening to that crying baby for the rest of your flight after your primary pair eventually breaks.

A Photocopy Of Your Passport
2. A Photocopy Of Your Passport

This is a must for all travel situations. If you have a color copy of the first two pages, you're likely to get a replacement quickly, should something happen to the original.

Rain Poncho
3. Rain Poncho

It doesn't take up much space in your bag and you'll be glad to have it if the weather is bad when you land.

Universal Adapter Plug
4. Universal Adapter Plug

If you're traveling abroad, you'll want to keep this helpful device on you at all times. That is, unless you hate electricity or something.

A Copy Of Your Favorite Magazine
5. A Copy Of Your Favorite Magazine

Surprise! Most planes don't have wifi (unless you want to pay extra!), which means you'll have to resort to good old fashioned printed media as your in-flight entertainment. You might even make it all the way through an issue, so long as you remembered your extra headphones to block out the noise.

Pain Relievers
6. Pain Relievers

Between the air pressure changes and hours of sitting, pain relievers will likely come in handy. We especially like the night time versions for those longer flights.

Travel-Sized Toothpaste
7. Travel-Sized Toothpaste

Besides the fact that most airlines have strict rules that regulate the allowable size of containers for gels and liquids, you're not going to enjoy the taste in your mouth after downing a complimentary cup of airline coffee. Don't get caught without it.

Comfortable Shoes
8. Comfortable Shoes

There's nothing worse than getting stuck in heels or uncomfortable dress shoes for longer than you need to be, even if you're only sitting. Grab a broken-in pair of tennis shoes or your favorite slippers for the flight. Remember, nobody likes the barefoot guy.

Eye Drops
9. Eye Drops

Recirculated air can make your eyes extremely uncomfortable. Keep a small bottle (generally 3oz or less) in one of those plastic bags we mentioned, just in case.

Resealable Plastic Bags
10. Resealable Plastic Bags

You'll want a few extras of these, partially because of TSA regulations and partially because of cost effectiveness. It's the simplest way to organize your stuff.

An Envelope
11. An Envelope

Between receipts, boarding passes and other travel documents, you're likely to accumulate a lot of important records on your journey. Keep an envelope handy so you don't have to keep track of it all during your trip.

12. Snacks

Airplanes aren't movie theaters. You can, and should bring your own snacks — especially if you're someone who gets a little cranky between meals. Those little bags of pretzels are never enough anyway.

Antibacterial Wipes
13. Antibacterial Wipes

Airports attract a lot of people. And where there's people, there's tons of germs. Do yourself a solid and keep a few of these handy to help avoid feeling under the weather on your trip.

Diarrhea Medicine
14. Diarrhea Medicine

Not everyone is prone to this condition, but some people are and airplane bathrooms are snug, to say the least. Even just one dose can be the difference between a pleasant flight, and getting in a fight with the guy who is sitting in the aisle seat in your row. 

All Of Your Chargers
15. All Of Your Chargers

Because if your flight gets delayed and your batteries are almost dead, you might just die of boredom.

Business Cards
16. Business Cards

A well designed business card can be useful in any occasion, especially if you're traveling for work. After all, you never know who you'll be sitting next to during your flight.

Face Wipes
17. Face Wipes

Here's an inconvenient truth: your face is gross (don't worry, ours are too). Chances are you won't be showering anytime terribly soon either, so a few of these can be a godsend in a pinch.

Extra Glasses
18. Extra Glasses

OK, so obviously this only applies to people with impaired eyesight. An extra pair of glasses tucked in your carry-on bag won't seem like such a silly idea though, when your primary glasses break or your contact lenses dry out.

Travel Outlet Strip
19. Travel Outlet Strip

Heroes come in all shapes and sizes and none are more appreciated than the guy with extra outlets during a flight delay. Or you could just charge all of your devices at once. Your choice.

Document Holder
20. Document Holder

For the ultra-organized. If an envelope doesn't do it for you, then consider a handy, well-crafted document holder for all your important papers.

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