Second-Time Around Targets Target returns from ranges beyond that associated with a basic PRF interval. Sector 1- A part of airspace controlled by a team of controllers, defined, notably, by its geographical co-ordinates and its assigned radio frequency.
2- An area in which aircraft are under control of a single executive controller (ATCo). Several sectors make up the entire FIR.
Sector Delay (AMAN) The part of the total delay (expressed in terms of time) calculated for a flight in the sequence which can be absorbed within the sector defined.
Sector List The list of sectors to which an SFPL is to be posted. Note that this may encompass sectors not expected to be penetrated by the flight. Sector Suite The controller or group of controllers that are associated with an ATC sector. Sectorisation The concept of splitting up the FIR into several sectors. The goal of Sectorisation is to reduce the workload of a single air-traffic controller by a divide and conquer method. Having too many sectors, however, will increase the workload because of increased inter-sector communication. Security Label A Security Label may indicate requirements for protection of a PDU and provide information used by network layer access control functions. Security Management The purpose of security management is to support the application of security policies by means of functions which include the creation, deletion and control of security services and mechanisms, the distribution of security-relevant information and the reporting of security-related events. Segment A part of a route defined by entry and exit points, matching the area of responsibility boundaries. Selection Instrument Any method or device used to evaluate characteristics of persons. (SIOP, 1987). Selection Procedures Selection procedures provide guidelines for accepting, or rejecting, applicants for a job on the basis of data from application forms, psychological tests, personality inventories or interviews. Selection Ratio The percentage of those candidates considered who are selected. Selective Availability A set of techniques for denying the full accuracy and selecting the level of positioning, velocity, and time accuracy of GPS available to users of the Standard Positioning Service (L1 frequency) signal. Selective Calling A system which permits the selective calling of individual aircraft over radiotelephone channels linking a ground station with an aircraft.

 
Self Contained Navigation Systems which are not dependent on external navigation sources on a continuous basis to determine position or navigation track. Self-contained navigation systems must be updated periodically with station-referenced or earth-referenced navigation system so maintain their accuracy. Self-accuracy Accuracy of own performance on tasks. Self-confidence Confidence in own ability to successfully complete the tasks. Self-Monitoring Skills Used to evaluate, monitor and regulate the self-performance, including attention allocation, workload management and recognition of problem areas in performance. Specific form of strategy. Self-Paced Learning A learning/teaching system whereby the learner is able to control his/her works pace. Self-Selection The result of person’s self-assessment of his / her capabilities and character in comparison to job requirements. Sensitivity Time Control A circuit which controls the gain of a radar receiver, allowing it to rise from an initial preset value to maximum at a predetermined rate to compensate for the decrease in received signal strength as range increases. This can also be a dynamical threshold operation with fixed gain receivers, such that the threshold below which signals are discarded decreases with range. Also known as GTC (Gain Time Control). Separation (MTCD) Situation in which two aircraft do not violate the separation criteria. Separation criteria (MTCD) The required minimum vertical, lateral, and longitudinal distances between two aircraft in order not to be involved in an aircraft conflict, or a nominal routes overlap. Separation Minima The minimum required distance between aircraft. Vertically usually 1000 ft below flight level 290, 2000 ft above flight level 290. Horizontally, depending on the radar, 3 NM or more. In the absence of radars horizontal separation is achieved through time-separation (e.g. 15 minutes between passing a certain navigation point). Sequencing Process of establishing the order of arrival at a constraint point (e.g. FIR exit or IAF) or for a specific runway. Serious Incidents An incident involving circumstances indicating that an accident nearly occurred. Server System that manages and processes in an autonomous way a consistent set of functions and information, with as principal task to provide external Users with services relative to these functions and information. A system composed of Servers and Users is based on a principle of great independence in the processing: the Users have visibility on the provided services, but not on the way how the served information is derived. From the other side, the Server is unaware of the way how Users are applying the provided information. As a consequence, the interface Server/User is fixed (protocol, nature of service), whereas the internal organisation of the systems may change.