時間：2011-03-11 23:13來源：藍天飛行翻譯 作者：admin 點擊：次
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localizer offset (air traffic control). An angular offset of the localizer from the runway extended center line in a direction away from the no transgression zone (NTZ) that increases the normal operating zone (NOZ) width. An offset requires a 50-foot increase in the decision height (DH) and is not authorized for CAT II and CAT III approaches. localizer-type directional aid (air traffic control). A navaid used for nonprecision instrument approaches, with utility and accuracy comparable to a localizer but not a part of a complete ILS and not aligned with the runway. localizer usable distance. The maximum distance from the localizer transmitter at a specified altitude as verified by flight inspection, at which reliable course information is continuously received. local Mach number. The Mach number of any isolated, or localized, flow of air over an aircraft structure. Because of the shape of the aircraft structure, the local Mach number is often higher than the flight Mach number of the aircraft. Shock waves normally form on an aircraft structure when the air passing over the structure reaches a speed of Mach one, the speed of sound. local oscillator (radio receiver circuit). An electronic oscillator in a superheterodyne radio receiver. A superheterodyne receiver is highly selective because it selects an extremely narrow band of frequencies and rejects all frequencies on either side. A radio-frequency (RF) signal is picked up by the receiver and mixed with a signal produced by the local oscillator, which is tuned with the same tuning control used to select the RF signal. Since both the local oscillator and the RF signal are tuned at the same time, the frequency of the local oscillator is always the same number of kilohertz or megahertz different from the RF, regardless of the frequency of the RF. The difference frequency between the received RF and the frequency produced by the local oscillator is filtered and amplified through the remaining stages of the receiver. This frequency is called the intermediate frequency, the IF. local traffic (air traffic control). Aircraft operating in the traffic pattern or within sight of the tower, aircraft known to be departing or arriving from flight in local practice areas, or aircraft executing practice instrument approaches at the airport. locator (ICAO). An LF/MF nondirectional beacon used as an aid to final approach. locked-rotor current (electric motor specification). The steady-state current flowing through the windings of an electric motor when the rotor is held in a locked position with the rated voltage applied to it. Locked-rotor current is much higher than the running current, because as soon as the rotor begins to turn, it generates a counterelectromotive force that opposes the source voltage and decreases the running current. lockout debooster (brake system component). A component in an aircraft power brake system, used to reduce the pressure between the brake control valve and the wheel cylinder. A lock-out debooster shuts off the flow of fluid to the wheel cylinder if the line should break. See debooster. |
