时间：2020-03-15 10:34来源：蓝天飞行翻译公司 作者：民航翻译 点击：次
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Contaminated Runway For purposes of generating a runway condition code and airplane performance, a runway is considered contaminated when more than 25 percent of the overall runway length and width coverage or cleared width is covered by frost, ice, or any depth of snow, slush, or water. When runway contaminants exist, but overall coverage within the area of the runway that is being maintained is 25 percent or less, the contaminants will still be reported. However, a runway condition code will not be generated. Note: While mud, ash, sand, and oil are reportable contaminants, there is no associated airplane performance data available for these contaminants and no Runway Condition Code (RwyCC) will be reported. Mud is the only contaminant in this reference where a measured depth is reportable. Exception: Rubber is not subject to the 25 percent rule, and will be reported as Slippery When Wet when the pavement evaluation/friction deterioration indicates the averaged Mu value on the wet pavement surface is below the Minimum Friction Level classification specified in Table 3-2, Friction Level Classification for Runway Pavement Surfaces, of AC 150/5320-12, Measurement, Construction, and Maintenance of Skid- Resistant Airport Pavement Surfaces. Dry Runway/Pavement Use the term “DRY” to describe runway/pavement surfaces that are neither wet nor contaminated. A FICON NOTAM must not be originated for the sole purpose of reporting a dry runway. A dry runway surface should be reported only when there is need to report conditions on the remainder of the surface. Dry Snow Dry snow is snow that has insufficient free water to cause it to stick together. This generally occurs at temperatures well below 32° F (0° C). If when making a snowball, it falls apart, the snow is considered dry. Eutectic Temperature/Composition A deicing chemical melts ice by lowering the freezing point. The extent of this freezing point depression depends on the chemical and water in the system. The limit of freezing point depression, equivalent to the lowest temperature that the chemical will melt ice, occurs with a specific amount of chemical. This temperature is called the eutectic temperature, and the amount of chemical is the eutectic composition. Collectively, they are referred to as the eutectic point. FICON (Field Condition Report). A FICON is a Notice to Airmen (NOTAM) generated to reflect pavement surface conditions on runways, taxiways, and aprons and Runway Condition Codes (RwyCCs) if greater than 25 percent of the overall runway length and width coverage or cleared width of the runway is contaminated. Frost Frost consists of ice crystals formed from airborne moisture that condenses on a surface whose temperature is below freezing. Frost differs from ice in that the frost crystals grow independently and therefore have a more granular texture. Note: Heavy frost that has noticeable depth may have friction qualities similar to ice and downgrading the runway condition code accordingly should be considered. If driving a vehicle over the frost does not result in tire tracks down to bare pavement, the frost should be considered to have sufficient depth to consider a downgrade of the runway condition code. Ice Ice is the solid form of frozen water including ice that is textured (i.e., rough or scarified ice). Note: A layer of ice over compacted snow must be reported as ice only. Layered Contaminant A layered contaminant is a contaminant consisting of two overlapping contaminants. The RCAM identifies the approved list of layered contaminants, including: 1. Dry Snow over Compacted Snow 2. Wet Snow over Compacted Snow 3. Slush over Ice 4. Water over Compacted Snow 5. Dry Snow over Ice 6. Wet Snow over Ice Mud Mud is wet, sticky, soft earth material. |
