Eurocontrol reported this morning that a critical system problem had occurred at Amsterdam Airport Schiphol with a drastic reduction in the arrival rate. The radar correlation software, that is the interface between secondary and primary radar, was at fault.
The situation has been recovered now and rate for the arrivals has been improved though flight delays remain high.
Passengers planning to fly into or out of the affected airport should contact their airline well in advance of departure to confirm flight status.