Slot monitoring is performed by ACNL in cooperation with the airport and air traffic control authorities. Several types of monitoring are applicable for which procedures and regulations may differ per airport.

ACNL regularly compares the most recent slot information with information from the airport’s and air traffic control’s information systems. Regular monitoring procedures are in place for the following categories of inconsistencies in the use of slots:

• Unplanned night movements: Flights operated during the night regime  at Amsterdam Airport Schiphol without  a night slot.
• No-recs: Flights operated without cleared airport slots.
• No-ops: Cleared airport slots that have not been operated.