India two four:
As Mike said, when designing the airspace we have to 'prove' what we need and that this is the minimum required. When this airspace structure was first used in 2004, we were congratulated for its layout as it was easier than the previous layout and freed up a lot of airspace for transit traffic without reducing the 'protection' for display aircraft. The reason we have two 'packages' is because at times, the full 8nm radius is not required eg for low energy displays by vintage aircraft and during periods when there is intensive arrivals and departures, whereas for the main display the main package is required. Previously the 'main' package was in use all the time but we took into account the requirements of other airspace users and hence the two 'packages'. Would you prefer that we use the 'main' package (areas 1-7) all the time?