Christmas and New Year's flying guide: 6 things to know

Most holiday travel tips are the same from year to year, but there are some new things to keep in mind this year.

Ready or not, the winter holiday rush is here.

If you’re taking to the skies for Christmas, New Year’s or any of the other winter holidays, brace yourself for crowded airports and packed planes.

All told, 45.7 million passengers will fly on U.S. airlines during an 18-day holiday window that begins Thursday (Dec. 20) and ends Jan. 6, according to the Airlines for America (A4A) trade group.

That amounts to about 2.54 million passengers per day during the period, an increase of 126,000 travelers per day from the comparable window last year, A4A says.

The busiest days of the holiday period will be Thursday (Dec. 20) and Friday (Dec. 21), according to projections from both A4A and the Transportation Security Administration. Friday is expected to be the single busiest day of the period.

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Flyers also should expect long lines and busy terminals as travelers head home on the day after Christmas (Wednesday, Dec. 26), which is forecast to be the third-busiest overall.

Passengers are the least likely to endure crowds on Christmas Eve, Christmas Day and Saturday, Jan. 5. Those are projected to be the three slowest days of the holiday flights window.

What else do you need to know for this year’s holiday travel season?

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Most tips are the same from year to year: Arrive early. Brace for crowds. Pack smart. Frequent flyers won’t be surprised by that, but remember that you’ll be sharing airports and planes with travelers who may only fly once a year. That means rules and etiquette that “road warriors” take for granted may not even register to the “infrequent” flyers.

With that in mind, scroll down to brush up on the basics of holiday travel for this Christmas.

Arrive early (with an updated twist)

Yes, “arrive early” means get to the airport early enough to account for longer-than-normal check-in and security lines. This may seem like a staple, and it is. But there is one caveat for the 2018-19 holiday season that’s a bit different than in years past.

During other peak periods this year, a number of airports have experienced congestion not only in the terminals, but also on the access roadways leading to them. That means it’s taking many passengers longer just to get to the airport terminal, even if they’re in a cab or being dropped off by loved ones.

Similarly, some airports have hit capacity in their parking lots, slowing those driving themselves to the airport.

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A good rule of thumb for the holidays: Arrive at the airport 45 to 60 minutes earlier than you normally would. You’ll be glad you did, especially if you find yourself stuck in a security line filled with slow-moving families making their once-a-year holiday trip. Remember: If you miss your flight, this is a tough time of the year to find empty seats on other flights.

What’s new?

The TSA is increasingly asking travelers to take food items out of their carry-on bags when they go through screening checkpoints. The reason: Food items add to the clutter agents see when they view X-ray images of passengers’ luggage. Removing those items allows screeners to focus on other items and could help speed the process, TSA says.

Another new focus this year: Powders, including items like cosmetics, baby powder, protein powder mixes and ground coffee, among others. TSA wants flyers to check powder-like substances if they’re in containers larger than 12 ounces (350 milliliters) – roughly the size of a can of soda. Smaller items can be brought in carry-on bags, but agents will likely ask for them to be pulled out so they can be screened separately.

The updated powder guidance isn't a ban. But the risk for a traveler with a large container in a carry-on bag is that he or she could be forced to throw away a “suspicious” substance before clearing the checkpoint. The main security concern is improvised explosives, but TSA told USA TODAY earlier this year that it is also worried about fentanyl or pepper spray being brought into cabins.

The new food and powder guidelines follow an update from a year earlier when the agency began requiring flyers to remove all electronics larger than a cellphone from carry-on bags for screening. Flyers also now must place these items separately in bins to go through scanning.

Flyers using Precheck lines will be exempt from some of the updated guidelines, but it’s possible an agent still might ask for these items to be removed for screening.

But, food is OK?

It it’s solid, you’ll be allowed to bring it through the checkpoints. That includes items like fruitcake, most pies and other food items. Spreads, however, must comply with the TSA’s 3-1-1 liquid rule if they are to be brought onboard as a carry-on. The TSA says: “If you’re unsure if your food item should go in a checked bag, consider this: If you can spill it, spread it, spray it, pump it or pour it, then please pack it in your checked bag.”

Don’t wrap those gifts

Technically, you’re allowed to go through security checkpoints with gifts. But TSA warns “if your wrapped gift triggers an alarm, the gift might need to be unwrapped for TSA officers to resolve the alarm.” Another popular Christmastime item that can create checkpoint trouble is the snow globe. Snow globes also are allowed, but only if they contain less than 3.4 liquid ounces (per the agency’s 3-1-1 liquid rules). “The rule of thumb is that if it is smaller than a tennis ball, it is probably 3.4 ounces or less,” TSA says.

Pack smart

Pack your carry-ons with security lines in mind. Unless you’re eligible for the TSA’s Precheck lines, laptops and liquids must come out separately to go through the screening checkpoints. The same thing goes for large electronics and food items. Remember, these items must each be placed in their own bins as you go through security.

For the infrequent flyers, remember that most liquids are prohibited from carry-ons unless they are in containers of 3.4 ounces or less and are held in a clear, quart-size plastic bag. (See the TSA’s “3-1-1” rules on liquids). Some exceptions are made for liquids related to medical or childcare needs, but it may be smart to brush up on those rules.

Pack so that your laptops, liquids and other items can be quickly taken out of your luggage. That will not only speed up your trip through security, but will also shorten the wait for those behind you.

If you check a bag – either in advance or at the gate after your plane runs out of overhead bin space – remember to keep all of your important medicines and valuable items in your carry-on. If you’re forced to check a bag at the last moment, remove valuables as well as fragile items that could be damaged.

Pack your patience

Perhaps the golden rule of travel, this is especially important during the busy holiday rush.

Lines are longer and airports and airplanes are even more crowded than normal. Nerves fray more easily. But even when things get stressful, take a deep breath and smile. A courteous nod to a fellow traveler will increase the chances that they’ll be courteous to you.

And never take out your frustrations out on airline employees, most of whom are conscientious workers doing their best to get everyone on their way during an intensely busy time.

Even if you’re convinced your airline has wronged you, remember that these frontline workers often control your fate in getting to your final destination. Being polite and respectful will bring better service than being hostile or rude. Ask for a supervisor if you must, but know he or she may not have a different answer than the one you’ve already been given. Above all, always try to show everyone along the way the same respect you’d want.

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This article originally appeared on USA TODAY: Christmas and New Year's flying guide: 6 things to know