The airline base concept: European LCCs love to base aircraft and crew abroad, unlike others

easyJet's announcement on 25-Sep-2013 that it would open a new base in Hamburg illustrates the success of the European Union's decision to liberalise its aviation market in the 1990s. The UK's largest airline owes its success largely to these reforms, which allow any EU airline to fly from anywhere to anywhere within the bloc. Hamburg will be its 23rd base. No-frills rival Ryanair also took advantage of European liberalisation and now has 57 bases (including two outside Europe).

Nevertheless, there are still some barriers to this liberalisation. A recent court judgement ruled that Ryanair should have paid French social charges in respect of its employees based at Marseille, whom it employed on Irish labour contracts.

What is meant by an airline base? Why have Europe's LCCs established so many foreign bases and why is the practice of basing aircraft and crew away from an airline's home market rare outside Europe?