Survivability

Survivability is the ability to remain alive or continue to exist. The term has more specific meaning in certain contexts.

Engineering

In engineering, survivability is the quantified ability of a system, subsystem, equipment, process, or procedure to continue to function during and after a natural or man-made disturbance; e.g. nuclear electromagnetic pulse from the detonation of a nuclear weapon.

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. [Federal Standard 1037C in support of MIL-STD-188]

Military Survivability

In the military environment Survivability is defined as the ability to remain mission capable after a single engagement. Survivability comprises three elements:

* Susceptibility - the likelihood of being detected, identified, and hit
* Vulnerability - the effects of being hit by a weapon
* Recoverability - longer term post hit effects, damage control and firefighting, capabiltiy restoration or (in extremis) escape and evacuation.

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.

Naval Survivability

Survivability denotes the ability of a ship and its onboard systems to remain functional and continue designated mission in a man-made hostile environment. [Said, M., Theory and Practice of Total Ship Survivability for Ship Design. Naval Engineers Journal, 107(1995)4, p. 191-203.] The naval vessels are designed to operate in a man made hostile environment, and therefore the survivability is a vital feature required from them. The naval vessel’s survivability is a complicated subject affecting the whole life cycle of the vessel, and should be considered from the initial design phase of every war ship. [Kotiranta, R., The Assessment of Naval Vessel’s Survivability against Explosion in Air based on a 3-D Product Model, 2006, p. 1]

The classical definition of naval survivability includes three main aspects which are susceptibility, vulnerability, and recoverability, although recoverability is often subsumed within vulnerability. [Reese, R. et al., Operationally Oriented Vulnerability Requirements in the Ship Design Process. Naval Engineers Journal, 110(1998)1, p. 19-34.] 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). [Kotiranta, R., The Assessment of Naval Vessel’s Survivability against Explosion in Air based on a 3-D Product Model, 2006, p. 1] 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 heavilyaffected 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. [Lake, J., Warship Survivability. Conference Proceedings of International Naval Technology Expo 80, Geneve, Sveitsi 1980, p. 28-50.]

Network

"The capability of a system to fulfill its mission, in a timely manner, in the presence of such as attacks or large-scale natural disasters. Survivability is a subset of resilience." [The [http://wiki.ittc.ku.edu/resilinets_wiki/index.php/Definitions#Survivability ResiliNets] Research Initiative definition of survivability.] [Abdul Jabbar Mohammad, David Hutchison, and James P.G. Sterbenz" [http://www.ittc.ku.edu/resilinets/papers/Mohammad-Hutchison-Sterbenz-2006.pdf Poster: Towards Quantifying Metrics for Resilient and Survivable Networks] ", "14th IEEE International Conference on Network Protocols (ICNP 2006)", Santa Barbara, California, USA, November 2006]

“The capability of a system to fulfill its mission, in a timely manner, in the presence of attacks, failures, or accidents.” [R. J. Ellison, D. A. Fisher, R. C. Linger, H. F. Lipson, T. Longstaff, N. R. Mead, " [http://wiki.ittc.ku.edu/resilinets_wiki/index.php/Survivability#.5BEllison-Fisher-Linger-Lipson-Longstaff-Mead-1999_..5D Survivable Network Systems: An Emerging Discipline] ", Carnegie-Mellon Software Engineering Institute Technical Report CMU/SEI-97-TR-013, 1997 revised 1999]

See also

* Availability
* List of System Quality Attributes

References

External links

* The [http://wiki.ittc.ku.edu/resilinets_wiki ResiliNets] Initiative
* [http://www.bahdayton.com/SURVIAC/PDF/SHBSVol1HDBKSeries.pdf Aerospace Systems Survivability Handbook - Vol. 1 Handbook Overview]
* [http://www.survivability.fi SURMA] Naval Survivability Assessment Software