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 airports/air traffic controls data and other sources. 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.
• COORD/ACTUAL: Coordinated slot compared with the Actual time and/or way of operation.

The overview below indicates for every type of misuse a short name, non-exhaustive examples, the legal basis, the WASG reference, the sanctioning conditions, the respective enforcement and what the options for sanctions are: