时间：2011-03-11 23:18来源：蓝天飞行翻译 作者：航空 点击：次
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VFR over-the-top. 14 CFR Part 1: “The operation of an aircraft over-the-top under VFR when it is not being operated on an IFR flight plan.” VFR-On-Top (flight conditions). A flight condition in which a pilot flies an aircraft according to visual flight rules (VFR) above a solid layer of clouds. While flying in the clear above the clouds, the pilot can operate under visual flight rules, but in order to reach VFR-On-Top conditions, the aircraft must pass through the clouds. When flying through the clouds, the aircraft must be operated according to instrument flight rules (IFR). VFR terminal area chart. An aeronautical chart, drawn to a scale of 1:250,000 (one inch is equal to four statute miles). This chart depicts terminal control area (TCA) airspace which provides for the control or segregation of all aircraft within the TCA. The topographic and aeronautical information depicted on terminal area charts includes visual and radio aids to navigation, airports, controlled airspace, restricted areas, obstructions, and related data. VHF (very-high frequency) (radio frequencies). The range of radio frequencies between 30 megahertz (30,000,000 cycles per second) and 300 megahertz (300,000,000 cycles per second) that are used for aviation communications and navigation. VHF radio waves operate much like light waves, in that they travel in straight lines and are usable only for a line-of-sight distance. VHF radio waves do not follow the curvature of the earth. VI (viscosity index). A measure of the change in the viscosity of a fluid with a change in its temperature. The higher the viscosity index, the less the viscosity changes with the temperature. vibrating-reed frequency meter. A type of panel-mounted instrument used to show the frequency of the alternating current being supplied to certain electrical equipment. Metal reeds of different lengths are vibrated by an electromagnet powered by the AC whose frequency is being measured. The reed whose resonant frequency is the same as the frequency of the AC will vibrate with a much greater amplitude than the other reeds. The ends of all of the reeds are visible on the face of the instrument, and each reed is identified by the frequency at which it is resonant. The number beside the reed seen as a wide blur is the frequency of the AC. vibration. A periodically reversing motion in which a body moves from one side to the other of its at-rest position. Every physical body has a natural resonant frequency at which it vibrates with the greatest amplitude for a given amount of excitation. vibration isolator. A device installed between a component and a structure to prevent any vibrations present in the structure from being transmitted into the component. Instruments and electronic components are mounted in aircraft with vibration isolators to keep the shocks and vibrations from damaging them. Vibration isolators are often called shock mounts. vibration loop (fluid lines). A loop formed in a rigid fluid line to prevent vibration from concentrating stresses that could cause the line to break. |
