Can I buy plane tickets using my old international passport while the new one is not yet issued?

Yes, you can do this, and it is sometimes practiced by tourists if the passport is still being processed but a profitable tour or air tickets come up that need to be purchased quickly. Then, when booking a ticket or tour, you can enter the old document's details or even arbitrary data in the passport number and validity fields, and then make corrections after receiving the new passport. However, note that for most airlines this is a paid service, and not a cheap one. It is much easier to change data when purchasing tours with charter flights, since tour operators are more lenient on this issue.

You should find out about the cost and possibility of making changes to air tickets with the new real passport data in advance before purchasing, so as not to end up in an unpleasant situation with a very high price for changes. If you buy tickets directly from the airline, you can find this out in the fares and conditions on the airline's website or from the support service. If you buy a package tour, you need to check with the tour operator or travel agent, because for charter flights of the same airline, completely different conditions apply than when buying tickets for a regular scheduled flight, and they are usually more lenient.

And importantly! Do not ask such questions in chats and tourist forums, as you may accidentally or even intentionally receive false information there, and you will have to deal with the consequences yourself.

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