時間：2011-03-11 23:18來源：藍天飛行翻譯 作者：航空 點擊：次
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prearranged coordination (air traffic control). A standardized procedure which permits an air traffic controller to enter the airspace assigned to another air traffic controller without verbal coordination. The procedures are defined in a facility directive which ensures standard separation between aircraft. precession (gyroscopic characteristic). One of the two basic characteristics of a gyroscope. The other basic characteristic is rigidity in space. Precession causes a force applied to a spinning gyroscope to be felt, not at the point the force is applied, but at a point 90° in the direction of rotation from that point. precious metal. Metals that are valuable because they are scarce. Gold, silver, and platinum are examples of precious metals. precipitation (meteorology). Any or all forms of water particles, whether liquid or solid, that fall from the atmosphere and reach the surface. Precipitation is a major class of hydrometeor and is distinguished from cloud and virga in that it reaches the surface. precipitation heat treatment. A method of increasing the strength of heat-treated aluminum alloy. After the aluminum alloy has been solution-heat-treated by heating and quenching, it is returned to the oven and heated to a temperature lower than that used for the initial heat treatment. It is held at this temperature for a specified period of time and then removed from the oven and allowed to cool slowly. Precipitation heat treatment is also known as artificial aging. precipitation static (radio interference). A form of radio interference caused by rain, snow, or dust particles hitting the antenna and inducing a small radio-frequency voltage into it. precision approach. 14 CFR Part 1: “A standard instrument approach procedure in which an electronic glide slope is provided, such as ILS and PAR.” precision approach radar. See PAR. precision switch (electrical component). A snap-action switch that requires a very small amount of movement for its actuation. The amount of movement needed is the same each time the switch is actuated. Precision switches are used in position-indicating circuits and as limit switches to start or stop an action any time a mechanical device reaches a specific position. preferential routes (air traffic control). Preferential routes are adapted in ARTCC computers to accomplish inter/intrafacility controller coordination and to assure that flight data is posted at the proper control positions. Locations having a need for these specific inbound and outbound routes normally publish such routes in local facility bulletins, and their use by pilots minimizes flight plan route amendments. When the workload or traffic situation permits, controllers normally provide radar vectors or assign requested routes to minimize circuitous routing. Preferential routes are usually confined to one ARTCCs area and are referred to by the following names or acronyms: . Preferential departure route (PDR). |
