Procedural corridors use agreed procedures to simplify the routing of traffic into and out of airports when the additional complexity of airport operations prevents ATCOs from relying on vertical crossings.
Contingency Flight Level Allocation Schemes (cFLAS) cannot, typically, be extended to arrivals and departures at airports given the inherent complexity in these operations. However, procedural corridors can be used to provide limited, simplified access to airports.
Contingency Flight Level Allocation Schemes (cFLAS) would generally not allow departures and arrivals from airports within the area concerned. In some circumstances it may be possible to design procedural “corridors” to and from some airports, perhaps with the help of air navigation service providers (ANSPs) of neighbouring states. The viability of these arrangements will be based around a host of factors such as the proximity of the selected airport to a country's borders and the ability of neighbouring states to offer assistance.