For a given application, survivability must be qualified by specifying the range of conditions over which the entity will survive, the minimum acceptable level or post-disturbance functionality, and the maximum acceptable outage duration.
The European Survivability Workshop introduced the concept of "Mission Survivability" whilst retaining the three core areas above, either pertaining to the "survivability" of a platform through a complete mission, or the "survivability" of the mission itself (i.e. probability of mission success). Recent studies have also introduced the concept of "Force Survivability" which relates to the ability of a force rather than an individual platform to remain "mission capable".
There is no clear prioritisation of the three elements; this will depend on the characteristics and role of the platform. Some platform types, such as submarines, minimise their susceptibility and may to some extent compromise in the other areas. Main Battle Tanks minimise vulnerability through the use of heavy armours. Surface warship designs tend to aim for a balanced combination of all three areas.
The classical definition of naval survivability includes three main aspects which are susceptibility, vulnerability, and recoverability, although recoverability is often subsumed within vulnerability. Susceptibility consists of all the factors that expose the ship to the weapons effects in a combat environment. These factors in general are the operating conditions, the threat and the features of the ship itself. The operating conditions, such as sea state, weather and atmospheric conditions, vary considerably and their influence is difficult to address (hence they are often not accounted for in survivability assessment). The threat is dependent on the weapons directed against the ship and weapon’s performance, such as the range. The features of the ship in this sense include platform signatures (radar, infrared, acoustic, magnetic), the defensive systems on board such as surface to air missiles, EW and decoys, and also the tactics employed by the platform in countering the attack (aspects such as speed, manoeuvrability, chosen aspect presented to the threat). Vulnerability refers to the ability of the vessel to withstand the short term effects of the threat weapon. Vulnerability is an attribute typical to the vessel and therefore heavily affected by the vessel’s basic characteristics such as size, subdivision, armouring and other hardening feartures, and also the design of the ship's systems, in particular the location of equipments, degrees of redundancy and separation and the presence within a system of single point failures. Recoverability refers to vessel’s ability to restore and maintain it’s functionality after sustaining damage. Thus recoverability is dependent on the actions aimed to neutralize the effects of the damage. These actions include fire fighting, limiting the extent of flooding and dewatering. It shall be noted that besides the equipment also the crew has a vital role in recoverability.