时间：2011-04-18 00:52来源：蓝天飞行翻译 作者：航空 点击：次
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2. If the pilot of the lighter following aircraft has visual contact with the preceding heavier aircraft and also with the runway, the pilot may further adjust for possible wake vortex turbulence by the following practices: (a)Pick a point of landing no less than 1,000 feet from the arrival end of the runway. (b)Establish a line.of.sight to that landing point that is above and in front of the heavier preceding aircraft. (c)When possible, note the point of landing of the heavier preceding aircraft and adjust point of intended landing as necessary. EXAMPLE. A puff of smoke may appear at the 1,000.foot markings of the runway, showing that touchdown was that point; therefore, adjust point of intended landing to the 1,500.foot markings. (d)Maintain the line.of.sight to the point of intended landing above and ahead of the heavier preceding aircraft; maintain it to touchdown. (e)Land beyond the point of landing of the preceding heavier aircraft. 3. During visual approaches pilots may ask ATC for updates on separation and groundspeed with AIM respect to heavier preceding aircraft, especially when there is any question of safe separation from wake turbulence. 7.3.9. Air Traffic Wake Turbulence Separations a. Because of the possible effects of wake turbulence, controllers are required to apply no less than specified minimum separation for aircraft operating behind a heavy jet and, in certain instances, behind large nonheavy aircraft (i.e., B757 aircraft). 1. Separation is applied to aircraft operating directly behind a heavy/B757 jet at the same altitude or less than 1,000 feet below: (a)Heavy jet behind heavy jet.4 miles. (b)Large/heavy behind B757 . 4 miles. (c)Small behind B757 . 5 miles. (d)Small/large aircraft behind heavy jet . 5 miles. 2. Also, separation, measured at the time the preceding aircraft is over the landing threshold, is provided to small aircraft: (a)Small aircraft landing behind heavy jet . 6 miles. (b)Small aircraft landing behind B757 . 5 miles. (c)Small aircraft landing behind large aircraft. 4 miles. REFERENCE. Pilot/Controller Glossary Term. Aircraft Classes. 3. Additionally, appropriate time or distance intervals are provided to departing aircraft: (a)Two minutes or the appropriate 4 or 5 mile radar separation when takeoff behind a heavy/B757 jet will be: (1) From the same threshold. (2)On a crossing runway and projected flight paths will cross. (3)From the threshold of a parallel runway when staggered ahead of that of the adjacent runway by less than 500 feet and when the runways are separated by less than 2,500 feet. NOTE. Controllers may not reduce or waive these intervals. Wake Turbulence 7.3.7 b. A 3.minute interval will be provided when a small aircraft will takeoff: 1.From an intersection on the same runway (same or opposite direction) behind a departing large aircraft, 2.In the opposite direction on the same runway behind a large aircraft takeoff or low/missed approach. NOTE. This 3.minute interval may be waived upon specific pilot request. c. A 3.minute interval will be provided for all aircraft taking off when the operations are as described in subparagraph b1 and 2 above, the preceding aircraft is a heavy/B757 jet, and the operations are on either the same runway or parallel runways separated by less than 2,500 feet. Controllers may not reduce or waive this interval. d. Pilots may request additional separation i.e., 2 minutes instead of 4 or 5 miles for wake turbulence avoidance. This request should be made as soon as practical on ground control and at least before taxiing onto the runway. NOTE. 14 CFR Section 91.3(a) states: “The pilot.in.command of an aircraft is directly responsible for and is the final authority as to the operation of that aircraft.” e. Controllers may anticipate separation and need not withhold a takeoff clearance for an aircraft departing behind a large/heavy aircraft if there is reasonable assurance the required separation will exist when the departing aircraft starts takeoff roll. Wake Turbulence 7.3.8 Section 4. Bird Hazards and Flight Over National Refuges, Parks, and Forests 7.4.1. Migratory Bird Activity a.Bird strike risk increases because of bird migration during the months of March through April, and August through November. b.The altitudes of migrating birds vary with winds aloft, weather fronts, terrain elevations, cloud conditions, and other environmental variables. While over 90 percent of the reported bird strikes occur at or below 3,000 feet AGL, strikes at higher altitudes are common during migration. Ducks and geese are frequently observed up to 7,000 feet AGL and pilots are cautioned to minimize en route flying at lower altitudes during migration. c.Considered the greatest potential hazard to aircraft because of their size, abundance, or habit of flying in dense flocks are gulls, waterfowl, vultures, hawks, owls, egrets, blackbirds, and starlings. Four major migratory flyways exist in the U.S. The Atlantic flyway parallels the Atlantic Coast. The Mississippi Flyway stretches from Canada through the Great Lakes and follows the Mississippi River. The Central Flyway represents a broad area east of the Rockies, stretching from Canada through Central America. The Pacific Flyway follows the west coast and overflies major parts of Washington, Oregon, and California. There are also numerous smaller flyways which cross these major north-south migratory routes. 7.4.2. Reducing Bird Strike Risks a.The most serious strikes are those involving ingestion into an engine (turboprops and turbine jet engines) or windshield strikes. These strikes can result in emergency situations requiring prompt action by the pilot. |
