How to book the same flight as someone else

To book the same flight as someone else, you need three things from their booking: the airline, the flight number and the departure date. With those, search that route and date on any booking site, find the flight whose number and departure time match theirs, and buy a seat. You do not need their name, their booking reference or their permission — a seat on a commercial flight is sold to anyone who wants it. Your reservation will be entirely separate from theirs, which matters later when you want to sit together.

What to ask them for

A screenshot of the confirmation email is the fastest thing to ask for. On it, look for a two-letter airline code followed by one to four digits — DL 264, UA 918, BA 117. That is the flight number, and it is unique for that airline on that day. Also note the departure date, the two three-letter airport codes (JFK, LHR, LAX) and the scheduled departure time. Everything else on the confirmation — their full name, the six-character booking reference, the ticket number, the fare paid — is irrelevant to you and should not be shared around.

One caution: a confirmation for a return trip or a connection lists several flights. Make sure you are matching the leg you actually want. If they connect through a hub, you will need to book both legs to travel with them the whole way.

The manual method, step by step

1. Open Google Flights, Skyscanner or the airline's own site and search the exact route and exact departure date from their confirmation. Use one-way first, even if you want a return — it makes matching easier.
2. Filter the results to that one airline. On Google Flights this is under Airlines; most sites have the same filter.
3. Narrow by departure time. If theirs leaves at 22:58, ignore everything that is not close to that. Airlines often run the same route several times a day.
4. Open the result and confirm the flight number matches. Booking sites show it once you expand the itinerary details. If the numbers match and the date matches, it is the same aircraft.
5. Book. Then, if you want to sit together, deal with seats as a separate task.

The pitfalls nobody mentions

• The price will probably be different. Fares move constantly and airlines sell cheaper fare buckets first. If they booked three months ago and you are booking now, expect to pay more. This is normal and does not mean you found the wrong flight.
• Being on the flight does not mean sitting together. Two separate bookings are two separate records as far as the airline is concerned. See how to sit together when you booked separately.
• Basic economy usually cannot choose seats. On most US carriers the cheapest fare either blocks seat selection entirely or charges for it, and seats get assigned at check-in. If sitting together matters, buy at least the next fare up.
• Codeshares list a different operating carrier. Their confirmation may say "AA 6123 operated by British Airways". The aircraft is the British Airways flight — you may find it listed as BA 117 instead. Search by the operating carrier and match the departure time; the marketing number is just a label.
• Flights sell out. If the flight no longer appears, it may simply have no seats left in any purchasable fare class. Check the airline's own site before giving up — it sometimes has inventory that third-party sites do not.

If you are booking for them rather than with them

You can buy a ticket in someone else's name. Enter their full name exactly as it appears on the passport or government ID they will travel with, plus their date of birth. The payment card does not have to belong to the passenger. Names cannot usually be changed after ticketing, so check the spelling twice before paying.