This holiday season, I'm carrying a little something extra on the airplane: knowledge at my fingertips.

As I pack for my upcoming trip, the Fly Delta app (other airlines have their own) on my cellphone alerts me: "16 hours until check-in." When those 16 hours are up, I'll check in using the app, too, and it'll upload my boarding pass onto my phone. The app also lets me save parking information — I can make a note on the parking page or take a photo — so I'll remember where the car is when I return.

Once inside the airport, I'll switch over to the My TSA app. It clocks wait times at the security checkpoints at Minneapolis- St. Paul International, so I'll know which one I can get through most quickly. The TSA app also has a "Can I bring?" function that helps sort out what you can pack in checked bags and what you can carry onto the plane.

Which brings me to the reminders I like to share ahead of the busy holiday season.

3-1-1 Rule: Any liquids, aerosols, gels and creams — think lipstick, lotion, yogurt — are limited to 3.4 ounces or less per item, and all must fit into one quart-sized zip-lock bag. This is also known as the 3-1-1 liquids rule.

Security checkpoints: To help these run smoothly, please remove your shoes, belts and jackets (unless you're under age 13 or 75-plus). Coins, watches, computers and those clear zip-top bags of liquids should also be placed in bins to be X-rayed (and so they don't set off alarms). May I recommend loafers for ease of slipping on and off?

Luggage size: Beware the size of your carry-on. In recent years, airlines have discreetly reduced the allowable size and begun enforcement at the gate. For most airlines, bags must be no larger than 45 linear inches in combined length, width and height, handles and wheels included.

Contact travel editor Kerri Westenberg at travel@star tribune.com; follow her on twitter: @kerriwestenberg.