Eurocontrol:

Figures for December 2012 show traffic decreasing by 5.6%, the lowest level of monthly traffic for five years. When it comes to delays, total Air Traffic Flow Management (ATFM) delays decreased by 2.1% compared with December 2011, with a more significant drop for en-route ATFM delays. There was, however, a slight increase in airport ATFM delays. The average ATFM delay per flight remained stable at 0.9 minutes.

Adverse weather conditions affected major airports across Europe, including London Heathrow, Amsterdam Schiphol and Frankfurt Main. Several system implementations and upgrades also took place in December, though they had little or no impact on the network.

The full Network Operations Report for December 2012 can be accessed here.

Eurocontrol press release