Whenever I book tickets for a flight, I have to provide my address details, contact numbers and an email address. A contact number I understand and they'll email me confirmation to the email address. But what use do they have for my physical address? It seems pointless data gathering.
Firstly, not all airlines do. I booked a Philippines Air flight (through Expedia) last night that didn't require I enter my physical address.
So now that we've established that, we can look at those that do, and why.
- In case of disaster. Some airlines ask for an emergency contact name and phone, others merely ask for your physical address. It's another way of figuring out how to contact next of kin. Indeed when I went through an experience in South America, Interpol and the NZ Police used residential addresses to ensure they had the correct next of kin.
- For correspondence, mailing and advertisement. While some of us prefer the electronic world, it's so easy to delete emails - they know you'll likely open an envelope addressed to you. American Airlines confirms this (correspondence reason) in their FAQ. Air New Zealand used physical addresses to send out their latest AirPoints card offer.
- For corporate partners. Some airlines are linked with hotel chains, credit card numbers and the like. They may share information on your travelling habits, spending habits, and help to update each others' information. In addition, these partners may also send you junk mail..err...corporate correspondence, permitted by you if you ticked/didn't untick the right box, or agreed to some long terms and conditions.
- Lost baggage. In the event they need to return items to you, they have a place to send it. Your email could be blocked/hacked, phones get lost, but save for an earthquake, the luggage can at least be sent to your nearest airport. I had this in 2002 when my snowboard bag got mixed up with someone else's. They'd already looked up where I lived and re-routed it down to my city.
- If they're smart, and have your email and physical address, they can now send you targeted marketing - cheap flight from your home city, or hotel deals through their corporate partners.
- Historical reasons. Remember when companies started to ask for email addresses, and we all thought that was dumb? Now we completely expect it. But we're also happy to continue filling out the physical address, because we're so used to it. And they probably feel that a) they always got it, so why would they stop and b) the more you know about a customer, the better.
- I'm sure there's plenty of other reasons, but those are the ones I've heard of, experienced, or read about in the past, and can think of for now :)
Come to think of it, I'm kinda surprised now that I was able to get away with it at all. They did ask for my credit card billing address, but that's different to my physical address anyway!
There's one major reason other answers here seem to have missed out: whichever airline or online travel agent is processing your booking, if you pay by credit card or debit card online then they need your address as registered with your bank to authorise your transaction.
Well, technically any payment processor is supposed to use address in addition to card details such as CVV code to authorise the payment but some skip this step. Yes, you can authorise transactions with a bank without doing address verification, but in that case, in case of fraudulent transactions the chargeback rates are much higher. Since total value of each transaction airlines typically process can be high, higher chargeback rates will eat significantly into their costs - as well as if a particular airline is sending a higher percentage of fraudulent transactions by not doing address checking, then they may even get blocked by their payment processor.
Having your address for forwarding lost baggage, marketing purposes, et al is an added bonus that airlines / online travel agents get, but it may not be the biggest reason why they use it.
I might add another small reason, that is finance law. For example here in Czech Republic, all payments over CZK 10'000 (approx. EUR 400) should be done with a proper identification of both seller and buyer on the invoice.
Well, they just don't want anyone booking a ticket and not knowing who they are and as someone said an address is required in order to authorize your credit card. There is a lot of fraud in the airline business sadly.
And also, the computer system requires one. It does not require an address to create the booking, but an address is required to pay for the booking.
To create the booking, just a name and phone number is required plus the itinerary as basic information.
Also, the airlines used to do what's called TBM, Ticket By Mail. So they used to mail you a physical paper ticket. They are still using the old backend systems with fancy interfaces, but the information is still required to complete the transaction.
Actually Mark, that information you enter at the time of booking is not usually linked to your lost baggage data as they are usually two separate systems. So they will ask you for the information again if your bag is lost. Only as sometimes the bag is lost at the other end of your trip.