I found it almost impossible to get acceptable tickets to fly with my daughter if she reaches 2 years old during a round-trip.

Their website (I'm talking about 2 European companies, one low cost and one standard) don't allow to proceed even trying to pay the forward flight as a child as well.

Buying tickets for forward and return flights separately is not an option because the prices are 5-6 times higher. Their offices say I should be able to buy tickets as a child, but they should try on their own before...

As an alternative they might sell the tickets directly but with extra fees due to the offline procedure.

Of course, whenever possible, you can change the dates to avoid such a "problem", but I cannot find a reason why websites cannot charge one flight as infant and another as child, when the birthday happens in between.

Among all billions of passengers every year I assume it shouldn't be so uncommon.

Why do they discourage such a travel?

  • I would expect that many airlines will allow you to book the entire trip putting your daughter's age as 2, though you should check with the airline. I'm certain they will allow you to book a return flight putting your daughter's age as 3. A quick check of the terms and conditions or a call to the airline should tell you which. Jan 23, 2018 at 14:29
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    @djclayworth have you tried that? I thought they would derive the real age from the passenger/passport data, at least that's how I'd build such a system. To answer the last part of the question, they have accounted for this scenario by allowing the booking by phone but haven't implemented it on the website because there is no commercial imperative to do so.
    – user16259
    Jan 23, 2018 at 14:46
  • I’m surprised that a low cost carrier would give you a significantly higher price for two one-way flights compared to a round-trip. Which airline is that?
    – jcaron
    Jan 24, 2018 at 1:38
  • My sentence wasn't very clear. The example about the one-way flight isn't related to the low-cost company - I apologize for that.
    – Mark
    Jan 25, 2018 at 14:06

4 Answers 4


The answer to why it's so difficult is because infants under 2 don't have their own seats, while children over 2 do. Therefore:

  • Infant tickets are cheap (10% of adult fare is typical) because they cost the airline nothing, it's just two people in one adult seat. But because of this...

  • They don't want to give an essentially-free infant a child seat, because that will take up an actual seat that could have been sold to an adult at full price.

    • They can't let the child be booked as an infant on the way back, because there may be aviation regulations that prohibit seating a child over 2 as a lap child during takeoff/landing.
  • Consequently, most airlines have the policy that if a child turns 2 during the validity of the ticket, they're not eligible for an infant fare and have to purchase a child fare.

So your options are to purchase a child fare for the whole journey (which may require reaching out to a travel agent or the airline directly), or to purchase separate one-way tickets, one as infant and one as child.

That said, from personal experience flying with two-year-olds, I'd recommend biting the bullet and getting them their own seat, since at that age trying to hold them in your lap for a long flight on a packed plane is about as pleasant as wrestling with a bag of octopuses.

  • Good points. But it doesn't explain why it would require a travel agent to purchase both flights as child fare. I don't see any technical reason why the website cannot offer this option.
    – Mark
    Jan 25, 2018 at 14:00
  • @Mark Because one-way and return flights have separate fare constructions, and you can't price a return that has no seat one way (infant) but has a seat going back (child). Jan 25, 2018 at 21:24
  • @jpatokal ok, I understand that but it's a commercial reason, not technical one, right? I mean, it would be absolutely possible to book tickets with different configurations: the system would take care of that. Simply, they don't want to do this.
    – Mark
    Jan 26, 2018 at 7:21
  • No, it's a technical limitation as well: as said, the built-in expectation is that a passenger either has or does not have a seat on both legs of the return. Jan 26, 2018 at 9:44

As outlined in a related question, airlines never bother verifying the dates of birth you enter when checking in or purchasing a ticket. Therefore the simplest solution is to "age up" your daughter by a year and book a return child ticket instead of the cheaper infant ticket.

You may also complain to the airline about the quality of their booking systems, but there's not much you can do otherwise except going around the system in some way.

  • 5
    @NateEldredge how is age up going to get a cheaper price? If anything that is going to increase the cost for the first flight as well Jan 23, 2018 at 17:18
  • Sorry, I misread. I'm still uncomfortable with any strategy that involves a deliberate lie, however. Jan 23, 2018 at 20:42
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    @NateEldredge courts in Europe and the US have long recognized that "sticky"/non-negotiable contract have considerably less force than agreements where both parties have input. It is therefore perfectly acceptable to lie to the airline in many situations - e.g. you are free to buy a return ticket and then never use it, no matter what the TOS has to say. Personally I always book flights with the wrong passport number and DOB these days (unless ETA/ESTA is involved), as those details are thrown out by the airline anyway when you pass the boarding gate or check-in desk.
    – JonathanReez
    Jan 23, 2018 at 21:46
  • 3
    @NateEldredge I consider a lie to be deliberately choosing to present a person with false information. If someone refuses to allow the truth as an option, then choosing the most accurate out of the options presented is not a lie. And if several options are of roughly equal accuracy, I don't consider it unethical to pick the one most favorable. Jan 23, 2018 at 23:00
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    @Mark to a government official? Sure. To a private entity in a situation where you don't gain any profit from the lie? Unlikely.
    – JonathanReez
    Jan 25, 2018 at 15:15

Book the flight with the child's age as of departure, as a return trip, and you should have no problems.

  • Do you have proof, websites or other reasons to know that this works for the return trip?
    – Willeke
    Jan 23, 2018 at 16:05
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    Most airlines I've seen ask for the passenger's date of birth instead of their age, so this would not help. Jan 23, 2018 at 16:22
  • As @NateEldredge pointed out, all airlines I have seen ask for the DOB which should match the passport's DOB.
    – Newton
    Jan 23, 2018 at 16:28
  • As said in the question, it's no possible: the validation rules of the form don't allow this.
    – Mark
    Jan 25, 2018 at 14:03

Book your daughter's travel as two one-way trips, one as an infant and one as a child. Then call the airline and have them link the booking references to your round-trip one.

  • That would be more expensive for any international trip.
    – JonathanReez
    Jan 23, 2018 at 20:07
  • That is not true. It was years ago, but nowadays two one-ways add most of the time up to exactly the round trip.
    – Aganju
    Aug 9, 2018 at 22:17

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