Slot coordination
Slot coordination is the administrative system, run by a coordinator such as ACL in the UK or COHOR in France, that allocates take-off and landing times at airports where demand exceeds capacity. Airports are classed as Level 1 (no coordination), Level 2 (facilitated, meaning voluntary schedule adjustment) or Level 3 (fully coordinated, where a slot is mandatory). For business aviation the practical effect is that Level 3 airports need requests filed in advance through the operator's handling agent or a trip-support company, and slots can be refused at peak times. Events like the Cannes Film Festival, the Monaco Grand Prix or Art Basel can temporarily push normally open airports into slot coordination.