Always check the airport code on your ticket or you might get a nasty surprise

Many cities have two airports or more. It pays to keep an eye on the airport code when you book to avoid a nasty surprise – or to save money.

Who knew you should fly into Zurich or Munich if heading to the Austrian Alps? That some budget airlines fly to Girona-Costa Brava airport and not Barcelona (which is one hour away) as advertised? That if you want cheap flights you should fly from Stansted or Luton rather than Heathrow in London?

In Europe especially, it’s easy to overlook the most convenient or the cheapest airport, which mightn’t even be in the same country as your destination. Geneva is best for visitors to eastern France, and Copenhagen for southern Sweden, for example.

Ski resort St Anton is 90 minutes by train from Innsbruck. But although Munich will take you an extra hour, that’s less than you need for a domestic transfer – and cheaper too, because you avoid adding an Innsbruck flight onto your long-haul ticket.

Different airports in the same city tend to have different functions: JFK in New York for long-haul flights, LaGuardia for low-cost carriers and a wider selection of domestic routes. Your choice of airline might send you to an unexpected airport: Southwest Airlines uses Midway rather than O’Hare in Chicago.

If flying domestically, pick convenient Hongqiao over Pudong in Shanghai, or Haneda over Narita in Tokyo. And watch out because in some cities you might be required to transfer to a different airport for a domestic leg, such as in Buenos Aires.

Be particularly wary when booking budget airline tickets. Budget airlines use secondary airports because they have lower landing and gate fees, quicker taxiing and turnaround times, and less air-traffic congestion.

Examples are Subang airport rather than Kuala Lumpur International, and Don Mueang rather than Suvarnabhumi in Bangkok.

Neither of those really matters, but you might be surprised in Europe, where budget flights can land nowhere near your assumed destination, and land transportation ends up costing you more than your airline ticket.

For example, Paris-Beauvais is 108 kilometres from the city centre, Charles de Gaulle only 31 km, and with far superior public-transport options. Memmingen is 141 km from Munich, and Girona 107 km from Barcelona.

To avoid being wrong-footed, check their airport code when booking because flights might be advertised as Munich or Barcelona when they actually land in Memmingen (FMM rather than MUC) or Girona (GRO rather than BCN).

Some booking websites give the option to choose a specific airport, “all airports” in a city, or “nearby airports” – which might offer Pisa as well as Florence, for example.

There’s nothing wrong with alternative airports: they might even have a location or flight times that suit you better, and flights will probably be cheaper.

However, be aware of the distance from your destination, airport transfer choices and costs, and transport availability if arriving early in the morning or late at night. Some budget airports (such as Toluca outside Mexico City) have no public transport at all. Flyer beware.