Note 2: The required visual reference means that section of the visual aids or of the approach area which should have been in view for sufficient time for the pilot to have made an assessment of the aircraft position and rate of change of position, in relation to the desired flight path.
Decision complexity
The extent to which the machines' decision on when and how to intervene and support the task can be regarded as a simple and obvious choice.

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Decision Height The height on a precision approach at which a pilot must have the runway approach lights in sight to continue the descent, or if not, must initiate a go-around. Decision Maker Person(s) responsible for a judgement, conclusion or resolution reached or given. Decision Making Another basic function of ATC. Active cognitive process which selects a set of possible courses of action. Includes a weighing up of the pros and cons of different alternatives. Decision Making Ability The mental process by which operators recognise, analyse and evaluate information about themselves, the air traffic and the operational environment, leading to a decision. Decision Making of Selector The process of accurate separation between ‘valid positive’ and ‘valid negative’ applicants by the use of valid information from tests and other selection tools by decision makers. Decision Making Skill Skill that involves choosing the best among several alternatives, which is an essential part of good Decision Making. Decision Making Skill includes tactics which are applied in response to specific situations. These tactics are learned from experience, and aim at supporting and enhancing the controllers’ decision-making. Decision Making Strategy High-level skills for managing cognitive resources and performance, and a specific form of strategy. Decision Making Subsystem Group of persons responsible for a judgement, conclusion or resolution within a system. Decision-maker Person responsible for a judgment, conclusion or resolution reached or given. Decoder A device used to decipher replies received from transponders. Decomposition Structured analysis that breaks down higher level tasks into their component part such as the skills required, the decision required, consistent components, task complexity or concurrent tasks. Default Values A predetermined and agreed value to be inserted in fields that need to be filled but for which a specific value could not be defined. Defense Mapping Agency (United States) Recently changed to the National Information and Mapping Agency (NIMA). Defruiting A process by which aircraft replies accepted by the Interrogator-Responsor are tested by means of storage and a comparator for synchronism with the interrogation-repetition frequency. Only replies which are in synchronism (correlate on a repeated basis in range) will be output from the defruiter. Other replies are rejected as fruit or false. Degarbling See also Garbling