Some random events affect single airport I can think of:
- Aviation accident (like the Asiana incident at KSFO), caused all/most traffic to be delayed/cancelled for 1-2 weeks
- Protest/Rebel take over airport (Bangkok), and all operation is shut down for 1-2 weeks
- Flood, drought, earthquake, diseases, etc, that cause incoming pax to reduce, outgoing pax might be the same, or increasing, as people want to move out of the area ASAP?
- Snow/Sand storm/hurricane will cause delay and cancellation
- Major incidents: terrorist attack, Japan nuclear incident, demand drop for several months?
- Airports got upgrade (i.e. every time a major slots drop), more delay and cancellation due to terminal, runway, custom, .... upgrade
- Airport incident: A/C collision, birds moving season, fuel car accident, etc... causing delay/cancellation for 1 day
- Union strike, airline staff join in