Polar Diagrams Horizontal or vertical radiation diagram for a radar antenna, whereby the relative gain is plotted as a function of the relative azimuth (Horizontal Polar Diagram, HPD) or as a function of the relative elevation angle (Vertical Polar Diagram, VPD) generally with respect to the main beam axis. Polarisation Direction of die electrical field vector of radiated radar energy with respect to a plane tangential to the earth (horizontal, vertical, left-hand circular, right-hand circular, elliptical, etc.). Policy 1- A principle, plan or course of action pursued by an organisation. (Source: James Martin, Information Engineering 1990).
2- A set of guidelines within which decisions can be taken. Policy Information Base The PIB is contained within a BIS and consists of a set of policy statements specified by the Systems Manager which together describe the applicable Routing Policy. Polished Plots Target reports at the output of the plot filter which rejects false targets coming from fruit, reflections, etc. Alternatively they are called filtered plots. Position Location of a point or an object considered as a point in 3-D space. Position (error) Standard Deviation Standard deviation of the Position Error (at the moment of Track Stop). Position Analysis Questionnaire A widely used technique of job analysis to develop employee selection criteria. It provides a list of standardised skills and abilities required by the job as a whole, but does not emphasise particular tasks, and is often insensitive to cognitive requirements. Position Determination Error The accuracy with which a navigation sensor can calculate and provide an output of actual location in an operational environment. Position Dilution of Precision The ratio of user-referenced three dimensional position error to measurement error of a multilateration system. PDOP is the root-sum of HDOP and VIDOP. Position Error (Tracks) The square root of the sum of the squares of the differences in Reference position and Track position. Position Fix A derived location of an entity in a common co-ordinate system. Position Fixing Error The accuracy with which a navigation sensor in combination with a navigation computer can calculate and provide an output of actual location in relation to desired location in an operational environment. Positive feedback Feedback that contains reinforcing loops which produce exponential change. Change in one direction results in more and more change in the same direction. Positive feedback produces growth that would be out of control if it weren't for limits to growth.
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Post Traumatic Stress Disorder A severe and incapacitating form of stress-related disorder, capable of ending its victim’s functional life in a matter of moments while changing, forever, the life of the victim’s family. Potential Co-ordination Failure Non-conformancy A flight related situation that exists whenever a flight’s system trajectory indicates that the co-ordination conditions will not be met and no automated co-ordination facility is available. Potential Level Bust The notion that a flight may not level-off at its cleared level. Potential Level Bust Non-conformancy A flight related situation that exits whenever the flight’s vertical speed exceeds that specified by the applicable potential level bust threshold. Potential Level Bust Threshold A monitoring criteria parameter that determines whether a potential level bust non-conformancy exists. Whenever a flight’s climb/descent rate exceeds that specified by the appropriate threshold then a potential level bust non-conformancy exists. There may be several thresholds each being applicable within a specified distance of the cleared level that a flight is supposed to be attaining. Power The probability that a statistical test will yield statistically significant results (SIOP, 1987). Practice field A platform to try out and test various decisions to see how they will play out in the longer term. Precise Positioning Service The accurate positioning service provided by using both codes (CIA and P) and both carrier frequencies (L1 and L2) of GIPS; normally restricted to military users. Precise/Protected Code A spread spectrum direct sequence code that is used primarily by military GPS receivers to determine the range to the transmitting GPS satellite. Uses a chipping rate of 10.23 MHz. Precision In statistics precision is defined as a measure of the tendency of a set of random numbers to cluster about a number determined by the set. The usual measure is either the standard deviation with respect to the average, or the reciprocal of this quantity. In physics precision relates to the quality of the method by which measurements were made (i.e. the internal consistency of the measurement process). Precision Accuracy The accuracy of a position with respect to the geographic or geodetic co-ordinates of the Earth. Precision Approach A standard instrument approach procedure using a ground-based system in which an electronic glide slope is provided (e.g. ILS). Precursor, Action, Result, Interpretation method PARI is a structured interview method particularly useful for determining procedural skills. The expert develops a task specific problem, and the analyst then asks precursor, action, result, and interpretation questions. The expert then gives the problem to another expert to solve, and that expert works through the problem with the analyst, again asking to the probe questions. The data are then decomposed into cognitive procedures (steps) for performing the task. Predetermined force An external environmetal factor that is known that it will occur sometime in the future.
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