Speed Deviation Non-conformancy A flight related situation that exists whenever the difference between the flight’s ground speed and that expected, expressed as a percentage, exceeds that specified by the speed deviation threshold.
Speed Deviation Threshold A monitoring criteria parameter that determines whether a speed deviation non-conformancy exists.
Speed Test A test in which performance is measured by the number of tasks performed in a given time. Examples are tests of typing speed and reading speed. Also, a test scored for accuracy where the test taker works under time pressure. (CDSEPT, 1996).
Speediness The extent to which a test taker’s score on a test depends on the rate at which work is performed rather than on the correctness of the response. One index of speediness is the percentage of test takers who do not complete the test. (CDSEPT, 1996).
Spherical Error Probable The radius of a sphere within which there is a fifty percent probability of locating a point or being located. SEP is the three-dimensional analogue of CEP.
Split A generation of two plots by a radar extraction system for the same target for one passage of the antenna main-beam through the target.
Split Tracks Two or more tracks existing for the same aircraft maintained by split plots and/or correct plots.
Spread Spectrum A method for signal transmission which spreads the signal over a much wider frequency band than is actually required by the information being sent; GPS does this by modulating the carrier signal with a pseudo-random code. Spurious Plots(s) Unwanted radar plot not corresponding directly with an aircraft position (generally applied for SSR). Squint Error The Radar Squint Error is the angle between the physical radar axis and the actual axis of rotation. Squitter Periodic Broadcast of aircraft position to elicit transponder replies from potential threat aircraft. SSR Mode-A The identification of an aircraft as reported by its SSR transponder. This 12 bit code is manually set by the pilot on request of ATC. This code is often called the 'squawk ident’ and is usually represented as 4 octal digits (e.g. 0627). Special codes are reserved for emergency situations (7500 = hijack, 7600 = radio failure, 7700 = general emergency). (often abbreviated as: SSR code). SSR Mode-C The altitude of an aircraft as reported by its SSR transponder expressed in flight levels. Possibly values are between FL 12 and FL 1267. (Pronounced Mode Charlie). SSR Mode-S An enhanced mode of SSR which permits the interrogation of SSR equipped aircraft and addresser interrogation with two way data exchange for suitably equipped aircraft. SSR Transponder Most aircraft are equipped with a so-called SSR transponder. Ground radar can interrogate the SSR transponder by sending a high-frequency signal. The transponder then responds with a 24-bit code (called the SSR code) containing an identification (Mode-A) and altitude (Mode-C). The expression is a derivative of the words transmitter and responder. Stack Protocol stack. A set of co-operating OSI protocols selected from different layers of the basic reference model. Hence, "upper layer stack`* refers to session, presentation and application protocols, While "lower layer stack" refers to physical, data link, network and transport protocols. Stack Departure Time The time calculated by the metering function that a flight should leave the stack to arrive at the runway at the sequenced time of arrival (STA). Stagger (p.r.f.) Deliberate, controlled variation of the p.r.f. of a PSR to overcome blind speeds and decorrelate second time around replies. Deliberate, controlled variation of the p.r.f. of the SSR to prevent aircraft plots due to second-time around replies, or synchronous fruit. Stakeholder All parties directly and indirectly impacted by the effect of EATMP actions..
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