Air traffic control remains one of the least reformed sectors of aviation worldwide. A natural monopoly (even the most committed pro-marketeer would hesitate to propose individual aircraft receiving competing ATC instructions), national airspace is also regarded as a key strategic asset by virtually all countries. There have been a few examples of Air Navigation Service Providers (ANSPs) being “commercialised” in various degrees, notably in Australasia, Canada and the UK. On the whole these experiments have been successful, but as yet they have not spread very far, at least for the main en-route services, and have not involved full privatisation. Outsourcing to private companies has been more common in the provision of tower services at airports, with Spain becoming the latest country to seek to reduce costs (and the considerable power of the ATC unions) in this way. With the European Single Sky and SESAR initiatives, the European Commission is certainly pushing for radical reform of European ANSPs, but not for the first time there is resistance from some key countries.