Tip: to find a specific term, use the Acrobat search : click H on the binocular icon in the window bar menu
Height Above Touchdown Specifically, the height above the Runway Intercept Waypoint. In using this term for airborne equipment specifications, care should be taken to define the point on the aircraft (GPS antenna, wheel height, centre of mass) that applies. Height Monitoring Unit A system capable of measuring the geometric height of an aircraft for comparison with the geometric height of the flight level at which it is being flown. The North Atlantic Height Monitoring System is a hybrid system consisting of fixed based mode C multi-lateration height monitoring units (HMUs) and Global Positioning System (GPS) based height monitoring units (GMUs). The overall monitoring system will consist of 2 HMUs and approximately 40 GMUs. The HMUs will be located at Aberporth, Wales, U.K. and in Gander, Newfoundland, Canada. The GMUs are portable units that will be moved from aircraft to aircraft. Hertz A unit of frequency equal to one cycle per second. Heuristic Knowledge Knowledge that enables us to solve problems and adapt to new situations. Hierarchical Task Analysis Technique for analysing and representing tasks hierarchically. High Frequency The set of frequencies between 3 and 30 MHz. High Level Data Link Control A set of bit-oriented link level procedures. High Power Amplifier In the AMSS the HPA amplifies the transmitted RF signal (from the RFU) to the appropriate power level required to maintain the air-to-ground communications link. High-Fidelity Simulator A full size replica of CWPs including all equipment and computer programmes necessary to represent full tasks of the sector or of the tower and their environment. A spare operational position used as simulator is a good example of HI FI SIM. In the case of aerodrome it includes an out-of-the-tower view. Hit A hit denotes the reception by the aircraft equipment (transponder) of one usable set of interrogation pulses as evidenced by a reply code return, (i.e. receipt of 2 interrogation pulses and 1 control pulse). Holding An Aircraft flying a "racetrack" pattern based on a defined constraint point. Holding Point A specified location, identified by visual or other means, in the vicinity of which the position of an aircraft in flight is maintained in accordance with air traffic control clearances. Holding Procedure A predetermined manoeuvre which keeps an aircraft within a specified airspace whilst awaiting further clearance. A common holding procedure to hold over way-point X is to intercept a specified radial of X, fly over X, make a one-minute 180 degree turn right, fly straight ahead for one minute, make another one-minute 180 degree turn right (again intercepting the same radial of X) and flying over X again. Ignoring the possible effect of wind, proper counting yields a four-minute holding pattern.

Tip: to find a specific term, use the Acrobat search : click H on the binocular icon in the window bar menu
Holding Stack A defined area where aircraft are held prior to commencing an approach to the runway. Homoscedasticity A type of relationship between two variables, when the variance of Y is the same for all values of X and reciprocally. Horizontal Dilution of Precision The ratio of user-referenced horizontal position error to measurement error of a multilateration system. Horizontal Polar Diagram This is a polar plot of the antenna’s radiation pattern taken in the horizontal plane. Horizontal Separation Separation between aircraft expressed in terms of time, distance or angular displacement between tracks. Human Activity System A system in which the main components are people and their actions. Human Errors in ATM A technique for error analysis in ATM. Through the HERA Project the objective is to increase knowledge and understanding of human performance mechanisms in ATM and the human errors with which they are associated, and, based on such a review, to develop, test and validate a human error classification system aimed at contributing to the prediction, detection and recovery of human error in ATM. Human Factors A multi-disciplinary effort to compile and generate knowledge about people at work and apply that knowledge to the functional relationships between people, tasks, technologies and environment in order to produce safe and efficient human performance. Human Factors Engineering Discipline that applies knowledge of human capabilities and limitations to the design of technological systems. Human Factors Plan Plan for the integration of human factors in the system life-cycle. Human Factors Specialist The term is used widely and should be considered with caution, as there is no protection on this title. A human factors specialist usually has one of the following backgrounds: a degree in industrial psychology or cognitive psychology and some practical experience of human factors application; an engineering degree with some additional study in industrial or cognitive psychology and some practical experience of human factors application; an operational background with additional human factors training, and some practical experience. Human Factors Techniques Techniques which contribute to the management process where quality of the Human Factor is involved. Human Integration in Future ATM Systems The HIFA Project is aimed at making users and stakeholders aware of the importance and benefits (cost reduction, more safety and efficiency) of integrating human factors into the ATM life cycle, and at giving them the necessary knowledge to implement such programmes effectively within their organisation by providing the appropriate guidance material about human factors in ATM.