The CAA change the rules again.....press release:
Further progress made to safely minimise ash disruption
The UK Civil Aviation Authority (CAA) today reports a positive outcome from discussions with airlines, regulators, and aircraft and engine manufacturers resulting in new measures to reduce airspace closures caused by volcanic ash. These new measures will be available from midday tomorrow.
A new area of operations can now be introduced that creates a ‘Time Limited Zone (TLZ)’ between the black ‘No Fly Zone (NFZ)’ and the red ‘Enhanced Procedures Zone (EPZ)’. Aircraft and engine manufacturers, based on new research and analysis, have agreed that it is safe to allow operations in the new zone for a limited time at higher ash densities than is currently permitted.
To operate in the new zone airlines need to present the CAA with a safety case that includes the agreement of their aircraft and engine manufacturers. UK airline Flybe is the first to achieve this and will therefore be able to use the new zone from midday tomorrow.
This means that areas of our airspace that would have previously been closed can safely open, further minimising flight disruption.
Link here