Flights

A flight search returns a list sorted by price, which quietly hides most of what decides whether the journey is any good: which airport you land at, how long the connection is, whether a bag is included, and who you have to argue with if the flight is cancelled. Those four things move the real cost far more than a $30 difference in the headline fare.

It also helps to know what kind of site you are looking at. There are three:

• Airline websites sell their own seats. If something goes wrong they can rebook you on the spot, and they are legally the party responsible for the flight.
• Online travel agencies (Expedia and the like) sell many airlines’ seats and can combine them on one booking. Changes go through the agency, which adds a step but sometimes saves real money.
• Metasearch (Skyscanner, Google Flights) sells nothing. It compares, then hands you to whoever is actually selling. Excellent for finding out what exists; always check where it is sending you before you pay.

The single biggest variable is the airport, not the airline

Cities with more than one airport can turn a cheap fare into an expensive afternoon. Paris Beauvais is marketed as Paris and sits about 85 km north of it. Milan Bergamo, Stockholm Skavsta, Tokyo Narita versus Haneda — the pattern repeats worldwide. Before comparing two fares, price the transfer at each end and add it to both, then compare again. Quite often the ranking flips.

The same applies at the start of the trip. A flight from a secondary airport that needs a 05:00 taxi is a different product from one you can reach by train at a civilised hour.

Connections: how much slack is enough

A single ticket that includes a connection puts the airline on the hook — miss the onward flight because the first one was late and they must get you there. Two separate tickets do not work that way. If the first airline delays you, the second airline has sold you a seat you simply did not turn up for, and you buy a new one.

That distinction matters more than the layover length. On one ticket, the airline’s own minimum connection time is a reasonable guide. On separate tickets, leave hours — and if the legs are on different days, an overnight stay is cheaper than a walk-up fare.

Changing airport between legs (Gatwick to Heathrow, Narita to Haneda) is always a separate ticket in practice. Treat it as a day of travel, not a connection.

Read the fare, not the price

Basic-economy style fares are now standard on most airlines and they differ from each other. Before comparing, check four things on each fare: cabin bag allowance, checked bag cost, whether seat selection is paid, and whether the ticket can be changed at all. A fare that looks $60 cheaper and then charges $45 each way for a suitcase is more expensive.

Also check what happens if you need to change. Many cheap fares are not merely expensive to change — they cannot be changed, only abandoned.

Where to book flights

Common questions

Is it cheaper to book directly with the airline?

Not reliably. Airlines sometimes hold their lowest fares for their own site, and agencies sometimes discount below it. What booking direct does buy you is a simpler life if the flight changes, because there is one company to deal with rather than two.

Does clearing cookies or browsing privately get a lower fare?

There is no good evidence that airline pricing tracks individual browsing this way. Fares move because seats in a fare bucket sell out. Checking a route on different days tells you far more than clearing your cookies does.

What is the safest way to book a trip with two airlines that do not partner?

Either buy it through one agency that will issue it as a single itinerary, or leave enough time between the legs that a delay on the first cannot cost you the second. See how to plan a trip with several kinds of transport.