pool - a common reservoir of commodities, resources, etc
At an airport where slot allocation takes place, a pool shall be set up for each coordinated period and shall contain newly created slots, unused slots and slots which have been given up by a carrier during, or by the end of, the season or which otherwise become available.
Any slot not utilized shall be withdrawn and placed in the appropriate slot pool unless the non-utilization can be justified by reason of the grounds of the grounding of an aircraft type ...
