Connecting-flight guide: how much time to leave, and when it gets risky

Connecting flights are often markedly cheaper than nonstops on the same route. They are also the moment in a trip when the most can go wrong. The good news: almost all of the risk hangs on two decisions you make when you book — how much time you leave, and whether the itinerary is one reservation or two.

One ticket or two? The distinction that matters most

Understanding this split is the single most important thing to know about connecting flights, and most problems start here.

One reservation (through ticket)

Both flights sit under the same booking reference. If the first is late and you miss the second, the airline is obliged to put you on the next suitable departure at no extra cost. Your bag is usually tagged through to the final destination, so you do not collect and re-check it at the connection.

Separate reservations (self-transfer)

You have bought the two flights separately. The second airline has no idea you were on the first. If you are late, you lose the second ticket and have to buy another. You will need to collect your bag at the connection, check in again, and often clear passport control. Most combinations that look cheap belong to this type.

How much connection time should you leave?

The minimum connection times airlines publish assume everything runs to the minute. In real life you need a little more slack.

If it is the last flight of the day, add another step of slack. Miss a 09:00 connection and there are usually several alternatives the same day; miss a 21:00 connection and you may genuinely be spending the night at the airport.

How does baggage work on a connection?

• One ticket, same airline: the bag is usually tagged to the final destination and you do nothing at the connection.
• One ticket, alliance partner airlines: the bag is transferred in most cases, but always confirm at check-in.
• Separate tickets: you have to collect the bag at the first arrival, leave the airside area and check it in again for the second flight.
• Connections in the UK, the US and Canada: you may have to enter the country, so collecting and re-checking bags is often mandatory — and check transit-visa rules as well.

What happens if you miss the connection?

On one ticket the airline puts you on the next suitable flight at no extra cost. On flights within the EU and all flights departing the EU, if the delay is the airline's responsibility you may also be entitled to compensation once the delay at arrival exceeds set thresholds; on long waits, meals and a hotel if needed are provided as well.

On separate tickets there is no such protection. You have to buy a new last-minute ticket for the second flight, which usually costs several times what you saved on the connection. That is why generous slack on self-transfers is not optional — it is required.

Turning a connection into an advantage: the stopover

Some airlines let you stay more than 24 hours at the connection point for little or no extra fare. It is the cheapest way to see two cities on one trip. Stopovers are common at hubs such as Istanbul, Doha, Amsterdam, Reykjavik and Helsinki, especially on long-haul.

1. When you search, stretch the connection time and check the fare difference.
2. If the difference is reasonable, add one or two nights in the connecting city.
3. Confirm before you leave whether a transit visa is required.
4. At check-in, confirm that your bag will be delivered to you at the stopover.

Should you use a connection for event travel?

If you are going to a concert or a match, keep outbound connection risk as low as you can. A one-stop is acceptable if you are arriving the day before the event; if you are arriving on the day itself, a nonstop is almost always the right call. On the way home the risk is much lower — if you want to save, do it there.