This document contains the Outline Safety Case for the Enhanced Flexible Use of Airspace Process Operational Improvement 1B (OI-1B) which concerns enhanced real time civil/ military co-ordination. It presents the argument why e-FUA OI-1B is acceptably safe in principle to implement in ECAC States together with supporting evidence. All ECAC States should verify that the assumptions, safety assessment scope and conclusions of this Outline Safety Case are applicable to their specific national circumstances prior to implementing OI-1B in their State. Alternatively States may determine that changes are acceptably safe through their own documented safety assessment work.