WG C1.17 has considered major unreliability events and the steps planners must take to enable them to be adequately managed. The main objectives of the WG were given as follows: [to] identify suitable plans for the controlled management of failure due to unsecured events. Restoration plans are an integral part of the managed failure plan and will also be covered by this WG. The WG’s focus will not be “classical” investments that are the subject of normal investment planning policies, but rather aspects such as protection schemes, defence plans, restoration plans, etc. Having identified the possible technical answers, the second main objective of the WG is to provide guidance on the justification of the corresponding investments to the stakeholders.