時間：2011-03-11 23:11來源：藍天飛行翻譯 作者：admin 點擊：次
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ALTRVs are approved by the appropriate FAA facility. altitude restriction. An altitude or altitudes stated in the order flown, which are to be maintained until reaching a specific point or time. Altitude restrictions may be issued by ATC (air traffic control) because of traffic, terrain, or other considerations. “Altitude restrictions are canceled.” (air traffic control directive). A statement meaning that adherence to previously imposed altitude restriction is no longer required during a climb or descent. altitude sensing unit (turbine engine fuel control). See ASU. altocumulus (meteorology). White or gray layers or patches of cloud often having a wavy appearance. Cloud elements appear as rounded masses or rolls and are composed mostly of liquid water droplets which may be supercooled. Altocumulus clouds may contain ice crystals at subfreezing temperatures. altocumulus castellanus (meteorology). A species of middle cloud of which at least a fraction of its upper part has evidence of vertical development. Vertical development shows up as billowing tops, some of which are taller than they are wide. This gives the top of the cloud layer a crenelated or turreted appearance, especially when viewed from the side. These clouds usually have a common base arranged in lines. Altocumulus castellanus indicates instability and turbulence at the altitude of the cloud. ALTRV (altitude reservation). Airspace utilization under prescribed conditions. ALTRV is normally employed for the mass movement of aircraft or other special user requirements which cannot otherwise be accomplished. alumel. An alloy of nickel, aluminum, manganese, and silicon that is the negative element in a thermocouple used to measure exhaust gas temperature. alumina. Natural aluminum oxide (Al2O3). Alumina occurs in nature in the form of corundum, a hard mineral crystal, or in the form of bauxite, a clay. aluminium. The British term for aluminum. aluminizing. A form of corrosion protection for steel parts. Molten aluminum is sprayed onto the steel by a high-velocity jet of air. The aluminum coating protects the steel from corrosion by preventing air or moisture reaching the surface of the steel. aluminum. A bluish-silvery, metallic chemical element whose atomic number is 13, atomic weight is 26.9815, and symbol is Al. Aluminum is produced from the clay bauxite, a form of aluminum oxide. Aluminum is lightweight, malleable, ductile, a good conductor of heat and electricity, and a good reflector of heat and light. Pure aluminum is highly resistant to corrosion. In its natural state, aluminum is soft and weak, but it can be alloyed with such metals as copper, magnesium, manganese, and zinc to give it strength. aluminum alloy. Aluminum to which has been added one or more other chemical elements. These alloying elements increase the hardness, toughness, durability, or resistance to fatigue of the aluminum. Aluminum alloys are the primary metals used in the construction of aircraft and other structures which require high strength and light weight. |
