In the evening of Thursday 18 June 2009 at 18:40 the flight plan data system (SYCO) of skyguide shut down for approximately two hours in the control centre of Geneva. The exact cause of this temporary shutdown is still unknown and is currently under investigation. The air traffic controllers immediately followed the procedures to be used in such cases. During the time of shutdown, the upper airspace traffic was rerouted over the neighbouring States, as agreed with the European Central Flow Management Unit (CFMU) and with adjoining air traffic control centres. The airspace capacity was impacted by the incident, with an average of 40 minutes of delay for about 30 flights from and to Geneva. Safety was at all times guaranteed, and the separation minima between aircraft were always respected.