17 Common Mistakes to Avoid When Booking a Flight

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If you don't fly a lot, it's easy to make costly mistakes when searching for and booking flights. And even if you're a frequent flyer, there are pitfalls you should make sure to avoid. TPG Contributor JT Genter rounds up a list of common mistakes that you should be wary of any time you book a flight.

Whether it's your first or two-hundredth time booking a flight, there's plenty of opportunity to make mistakes — especially when you're headed overseas. Even some of us on the TPG team have made unfortunate errors in the past. To help you minimize headaches, here's a list of common pitfalls to keep in mind whenever you're purchasing airfare.

1. Forgetting Travel Visa Costs & Time to Acquire

If you're headed out of the country, make sure to check the visa requirements for your destination. Don't make the mistake TPG Contributor J. Keith van Straaten made and get turned away at the airport for not having the required visa.

If you're headed to a country with a long visa application process, you might need to factor this processing time into when you can travel. For example, unless you already have a Russian visa, you're going to need to pass on any flight deals to Russia that leave in the next few weeks — unless you want to pay a lot more for rush processing.

Our friends over at Allied Passport are great about knowing the visa requirements and processing times. Allied Passport's website has a guide for every country, which lists visa requirements and — if applicable — a sample visa application to help you fill out your own.

2. Forgetting to Check Your Passport Expiration

Many countries require your passport to be valid at least six months after your entry date. So, double-check your passport expiration date before booking your international flight. If you're not going to have enough validity left, make sure to allow yourself enough time to renew your passport. And remember that the passport renewal "baby boom" is coming in 2017, so you might want to apply sooner rather than later.

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3. Forgetting to Check Nearby Airports

Heart set on traveling to a particular destination? Check to see if it's worth flying out of a nearby city. For our flight to Hong Kong last Thanksgiving, we flew out of Houston (IAH) for $769 round-trip. The prices out of our hometown of Austin (AUS) on the same travel days were more than $1,300! Often, you can also save quite a bit by flying into an airport near your destination.

If you use Google Flights to search your itinerary, it'll automatically check nearby airports for savings, and some Online Travel Agencies (OTAs) also have the option to search nearby airports. It can't hurt to check the box and see if you can save a bundle by making your drive to the airport a little longer. Of course, positioning to/from another airport takes time and comes along with an additional cost, so make sure that the flight savings is worth the hassle.

4. Booking the Wrong Airport

Portland, Maine (PWM) vs. Portland, Oregon (PDX); Birmingham, Alabama (BHM) vs. Birmingham, UK (BHX); Springfield, MO (SGF) vs. Springfield, IL (SPI): If you're booking a flight into a city with a common name, double-check that you picked the right one!

Thankfully, the US Department of Transportation requires airlines to allow you up to 24 hours to cancel your flight for free, but, depending on the airline, this policy may only apply when you're booking at least seven days in advance of travel. If you're rushing to make a last-minute flight purchase, double-check the flight details before purchase. If you're booking at least seven days out, take the time to re-check your flight details when you get your e-ticket confirmation email.

5. Forgetting to Factor in Ancillary Costs

Ever wonder why Spirit, Allegiant and Frontier can charge as little as $9 per flight? These airlines are banking on making money from you elsewhere. From baggage and seat selection costs to charges for food to fees for not printing your boarding pass before getting to the airport, these carriers are quite profitable thanks to the number of hidden fees they charge.

Before you jump on that cheap fare, make sure you factor in the other costs related to the flight. After you consider all the fees you'll need to pay, it might be cheaper to fly with another airline.

6. Booking With an OTA That Doesn't Allow Free 24-Hour Cancellations

Jumping on a great flight deal but need to ask for time off from the boss? Make sure to pay attention to the cancellation policy. Airlines are required to allow a free 24-hour cancellation policy, but OTAs can have more restrictive policies on refunds. While an OTA might be selling the same ticket for cheaper than other options, don't lock yourself into a flight you might need to cancel just to save a few bucks.

7. Forgetting to Research In-Flight Experience

Mileage runs aside, most people book flights to get to a destination. But don't forget that your time on the plane can have an impact on your trip. If you're so uncomfortable that you can't sleep on your red-eye flight to Europe, you're going to have a rough start to your adventure.

Check SeatGuru.com and TPG flight reviews to see what the onboard experience will be like. Need a good in-flight entertainment system? You might want to avoid planes that only have overhead projectors or make you wait for the "next showing" of a movie or tv show. Value good onboard service? You might want to pick the Cathay Pacific flight over the American Airlines flight.

Make sure to check the flight's seat pitch, especially if you're tall. Having your knees jammed into the seat in front of you — and/or having knees jammed into the back of your seat — might override any positives of the flight. TPG Editor-in-Chief Zach has compiled a handy visual comparison of various popular seat pitch lengths.

8. Getting "Stuck" with One Airline or Alliance

Airline elite status can be highly valuable. However, don't let loyalty and "chasing status" make you pay substantially more for your ticket. Don't just search your airline's website; also check Google Flights — or similar flight aggregators — to make sure that prices on other carriers aren't cheap enough to justify cheating on your airline.

9. Waiting Too Long to Book

If you know you're traveling, don't delay your flight purchase too long! Online travel agency CheapAir looked at 1.3 billion fares to determine that, on average, it's best to book domestic airfares around 54 days before departure. The "prime booking window" is anywhere between 21-112 days before departure. Don't wait until 20 days beforehand, as most discount airfares are going to require a 21-day advance purchase. While you might be able to snag a last-minute deal, odds are that you'll end up having to pay a lot more.

10. Booking the Wrong Dates

Especially when there's an incredible flight deal, it's easy to rush into making the purchase without double-checking the dates. In your rush, make sure you don't mistake "JUL" for "JUN" and show up at the airport a month early or late for your flight. That actually happened to a friend of mine when traveling for business. The airline's rebooking fees ate up most of the value of his originally booked ticket, and he had to pay last-minute fares to get to his destination on time.

11. Being Rigid on Dates

Although you might want to minimize time off from work by flying out on Friday night and returning Sunday night, these can be the most expensive times to travel. If you can afford two more days off from work, you might find substantial savings flying out Thursday and returning Monday. Besides, a Thursday-Monday itinerary would give you four nights at your destination; perfect for using the 4th Night Free benefit on the Citi Prestige Card.

Also note that if you use Google Flights to search your itinerary, it'll automatically check nearby dates for your consideration.

12. Overpaying for Larger Reservations

If you're booking for more than one person, you might end up paying more if you book together than separately. This is because the airline is going to default to the cheapest fare class that has enough availability for everyone in the party.

Say a group of five travelers are looking to book a flight. On the same flights, the airline might have two "deep-discount" tickets available for $250 round-trip, four "discount" tickets available for $300 round-trip and seven "full-fare" tickets available for $450 round-trip. If they all book together, the airline is going to sell them five of the most-expensive $450 "full-fare" tickets. But, they could break up their group into multiple purchases to save money. Note that this same concept can apply to award flight costs as well.

It's worth at least checking the price per ticket for a smaller number of travelers before purchasing all together. However, there could also be reasons to book as part of the same reservation — even if it costs a little more. If one of the travelers has elite status and the others don't, you might want to book as part of the same reservation for preferred seating, waived baggage fees, etc.

13. Entering the Wrong Traveler Name

Whether booking for just your family or a large group of passengers, make sure to enter everyone's correct legal name. Otherwise, it might be cheaper to legally change your name than change the name on the ticket.

14. Forgetting to Enter Known Traveler Numbers

If any travelers have a Known Traveler Number, make sure to add this number to the reservation as soon as possible. If this number is added too late, the traveler will probably miss out on getting TSA PreCheck for that flight.

15. Forgetting to Enter Frequent Flyer Numbers

In your rush to book your flight, don't forget to enter all travelers' frequent flyer numbers. If one of the passengers in your reservation has elite status, doing so might open up many more free seating options.

Even if no one has elite status and the flight won't earn many miles, you'll still want to enter everyone's number. Those small amounts could add up over time. Plus, the flight would be a mileage-earning event that'll extend the expiration date on your miles in most programs.

Flying on an international carrier and not sure where to credit your flights? WhereToCredit is a great resource to figure out which airlines are the best options.

16. Forgetting to Factor in Credit Card Travel Insurance

Once you're finally ready to book, you might default to using the credit card that you need to meet a spending requirement on. However, don't forget to factor in the travel insurance that's offered on certain credit cards — particularly on riskier itineraries. Perhaps you're flying on an independent or low-cost carrier or on a route that only has one flight a day (or less). What's your plan if the airline has a maintenance delay or cancels your flight? Booking with a credit card that has trip delay insurance can ease your worries.

The two credit cards with the best trip insurance are the Citi Prestige and Chase Sapphire Preferred. If you have a delay of over three hours, Citi's insurance policy will cover you for up to $500 per person in necessary expenses. Chase's insurance policy requires a delay of 12 hours or an overnight stay, but Chase will also cover up to $500 per person for a delay.

17. Forgetting About Currency Conversion Tricks

There are certain airlines where you can save quite a bit of money when you book in a non-US currency. The best example of this is Norwegian Air — where you can save ~25% by booking with Norwegian Krone.

I personally made the mistake of forgetting about this trick when I jumped on a $206 one-way flight on Norwegian. I remembered my mistake a few days later (when it was too late to cancel and rebook). When I checked the prices in both USD and Krone, I found that I could have saved ~$50.

Are there any other tips that you keep in mind when booking flights?