填空题 Collision between an aircraft and one or more birds is termed a bird-strike. Pilots sometimes record a birdstrike while at cruising altitudes, but most of them happen when an aircraft is relatively close to the ground, usually in proximity to an airport and during the circling, descent to land or take-off phases of a flight.
Birdstrikes may cause significant damage to an aircraft and/or, if the birds are ingested into a jet engine, a significant and sudden loss of power. If this were to happen during take-off or initial climb of a fully loaded passenger aircraft the results could be catastrophic-loss of the aircraft and the lives of those on board. Any bird is a potential hazard to aircraft and this is especially true as bird numbers and bird size increase.
Unfortunately airports themselves can be attractive to birds-rodents, insects and other small animals are a food source often found in flat grassed areas such as the runway strips. Even so, this problem can be reduced by careful habitat management or bird harassment techniques practised by airport maintenance and safety personnel.
Further problems may arise because the airport is located on bird migration routes. These may have existed prior to the airport site selection-but may not have been taken into account because the problem was not understood at the time-or have only been recently established because the birds have found an attractive new food source. Care needs to be taken by local authorities in deciding the location of rubbish tips, or when permitting other land uses that may be attractive to birds in this way. Of course these effects cannot always be anticipated with certainty since birds such as gulls have been recorded as travelling 50 kilometres or more from their roosting area to an attractive food source.
Agricultural uses may be thought desirable because they are compatible with high levels of noise exposure, but they can have an adverse effect on air-craft operations if birds are attracted during seeding or crop cultivation. Birds may also be attracted to pig farms where garbage is used as fodder. Even tree plantings can present a hazard if the species provides an attractive food source or nesting habitat.
Local authority planning schemes often apply strict controls on developments such as abattoirs, cattle feed lots, grain handling, piggeries, canals and marina developments, fish farms, and suchlike. In most cases these uses will not be permitted without a full environmental study. That study should be required to deal with the question of likely bird hazards if the proposed location is in proximity to an airport.
In some instances it may be necessary to consider ways of managing a particular land use in order to reduce its attractiveness to birds, for example the adoption of land-fill measures at garbage tips, or enclosed rather than open-air activity. Specialist ornithological opinion may be necessary. In such cases it may not be possible to implement immediate changes in land use, but this should not inhibit the adoption of long-term measures which are designed to achieve this.
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