How to check in online with British Airways

With British Airways, online check-in opens 24 hours before departure, on ba.com or in the airline's app. All it asks for is your booking reference and the passenger's last name. The boarding pass can then be printed, saved to your phone or sent to you by email. What varies is the closing time, which British Airways sets airport by airport.

Below we set out what you need before you start, how the process runs on the website and in the app, when check-in closes at your own airport, and what's left to do once you're there.

Online check-in opens 24 hours before the flight departs, on ba.com or in the British Airways app. That much is the same wherever you're flying from.

The closing time is where it gets specific. British Airways sets it airport by airport, and it also turns on whether the flight is short haul or long haul, so there's no single figure to work to. The exact time for your own flight is in Manage My Booking.

On a return booking the app will hold the boarding pass for the way back as well, as long as that flight departs within 24 hours. Connecting flights work the same way where the airport allows it.

Before you start, have the following to hand:

• your booking reference, the six-character code on the booking confirmation;

• the last name of the passenger, as it appears on the booking;

• your passport, or another accepted form of photo ID on domestic flights within the UK.

The booking reference mixes letters and numbers, and British Airways codes never contain a 1 or a 0. So anything that looks like one is an I or an O, which is worth knowing before you decide the code doesn't work.

One thing to sort out separately is Advance Passenger Information, the passport and travel details that many countries require before you fly. It goes into Manage My Booking rather than into check-in itself, and when something is still missing a red exclamation mark shows against the passenger details at the top of the page.

Now that you know what to have ready, we can go through the check-in itself, step by step.

The route is much the same whether you start on ba.com or in the app.

How to check in online with British Airways:

1. Go to Online check-in on ba.com, or open the British Airways app.

2. Enter your booking reference and the last name of the passenger, then select Start check-in.

3. Work through the steps and confirm the details you're asked for.

4. Choose how you want your boarding pass: printed, downloaded, emailed to you, or kept on your phone.

The difference is what the app can do on top of this. Both options are set out below.

If you booked through a travel agent or a booking site

Buying through an agent or a travel site doesn't change where you check in: it's still British Airways, on ba.com or in the app, and the form asks for the same two things.

The reference is where it can go wrong. Agents and booking sites issue confirmation numbers of their own, and those aren't always the six-character code British Airways uses to find the booking. If the one you're typing is refused, look back at the confirmation for a separate airline reference, and do bear in mind that a British Airways code never contains a 1 or a 0.

British Airways has a page showing where to find the reference for different types of ticket. If it isn't on yours, the agent who made the booking can give it to you.

Once check-in is done, the boarding pass can go wherever suits you:

• printed at home;

• downloaded to your computer or your phone;

• emailed to you;

• kept in the British Airways app, or saved to your Apple or Google wallet.

If it goes missing before you travel, a check-in kiosk at the airport will print it again.

At the airport

What's left when you get there depends on your baggage.

With hand baggage only and the boarding pass in hand, you can in most cases go straight through to security. One situation where you can't is if you're flying intercontinental from Heathrow Terminal 3 or Terminal 5, where passports and visas are checked at an Assistance desk first.

With a bag to check in, the Bag Drop is the next stop, and you'll need the boarding pass, your passport and any other documents the journey calls for. If you haven't got the pass, the check-in kiosks will print it. At Heathrow Terminal 5, Gatwick and London City you can tag and drop the bag yourself; at Heathrow Terminal 3 the kiosks print the bag tags and the bags then go to the Bag Drop area.

Whichever route you take, the closing time depends on the airport you're leaving from and on whether the flight is short haul or long haul. The exact one for your flight is in Manage My Booking.

At a small number of airports British Airways doesn't offer online check-in at all, and the check-in happens once you get there. The airports on that list are Bergerac, Dubrovnik, Guernsey, Fuerteventura, Isle of Man, Kefalonia, Montpellier, Perugia, Pula, San Sebastian, Split, Toulon and Tirana. Do check the current list on the British Airways website before you travel.

That means checking in at a desk, or at a self-service kiosk if the airport has one. The kiosks need only your booking reference or your passport.

The other case is the codeshare flight mentioned above, where the check-in may belong to the operating airline rather than to British Airways.

You checked in in good time, you got to the gate when you were meant to, and your booking was confirmed. Even so, a delay, a cancellation or an overbooked flight can still get in the way of your plans.

If that happens and the airline is responsible, UK261 entitles you to compensation of up to £520 per passenger, depending on how far you were due to fly. The rules cover every flight departing from a UK airport, whichever airline you're travelling with.

If your British Airways flight departs from an airport in the EU, the equivalent European rules apply instead, under Regulation EC 261/2004.

Being turned away at the gate is covered too: our guide to denied boarding sets out where you stand. And to see what you may be owed for your own flight, start with our British Airways compensation page.

Keeping track of your British Airways flight

With check-in out of the way, all that's left is the wait. It's well worth keeping an eye on your flight status in the meantime, particularly if you have a connection to make or someone meeting you at the other end.

British Airways publishes where its flights have got to on a Flight Status page, so you can see whether yours is running to time before you set off, and whoever is meeting you at the other end can do the same.

You could also use the free AirHelp app, which does one thing more: if your flight is delayed by more than 3 hours, is cancelled, or you're denied boarding, the app checks automatically whether you're entitled to compensation under UK261/EC 261 and lets you know.

With the AirHelp app you can:

• receive real-time notifications about delays, cancellations, gate changes and baggage reclaim;

• scan your boarding pass to add your flight quickly;

• share your flight status with whoever is picking you up;

• automatically check whether a disruption entitles you to compensation of up to £520;

• start your compensation claim straight from the app, with no paperwork.

The app is free and available on iOS and Android.