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Aviation History
1969
1969 - 1187.PDF
8 FLIGHT International, 2 January 1969 COLLISIONS BETWEEN BIRDS AND AIRCRAFT continue to be a great danger to both. Engines may be put out of action, windscreens and leading edges broken, crew and passengers killed or injured. In one example on July 15, 1962, a DC-3 of Indian Airlines hit a vulture near Lahore. The windscreen was smashed and the co-pilot killed. A vulture may weigh as much as 201b. The effect, however, may be much more serious. A Viscount of United Airlines ran into a flock of swans at 6,000ft over Ellicott City, Maryland, on November 23, 1962; at least two birds were hit. One of them penetrated the leading edge of the tailplane, came out at the rear surface and then damaged the elevator. Control was lost and 17 people were killed in the crash. A large swan may weigh up to 251b and they are gregarious migrators. On October 4, 1960, a Lockheed L-188 of Eastern Airlines was taking off from Boston when it ran into a flock of starlings, some of which were ingested into three of the engines. The sudden loss of power caused the aircraft to yaw and decelerate to a stall, from which it went into a spin. With only 150ft of altitude it had no hope of recovery. Of the 72 people on board, 62 were killed and nine seriously injured. The aircraft was destroyed. From the statistics available in recent years, it appears that about half the bird strikes occur at take-off. Some of the others happen at a considerable height, and involve either solitary vultures or flocks of migratory birds, swans and geese, often at night. Last year the Canadian National Research Council pub lished its Bulletin No 5, "Bird Hazards to Aircraft"—a very thorough review of the whole subject, the methods to be used against birds, and the assessment of the ability of aircraft to resist impact. Since about 50 per cent of incidents occur during take-off, the Council studied many airports in Canada and RCAF installations in Europe with a view to making them unattractive to birds. The cftort at the top of the page shows the migratory routes taken by various birds in the south-eastern area of the United States re produced from the "FAA Bulletin" BIRD STRIKES By MARCUS LANGLEY cEng, FRAeS, FIMechE This is another article in the series by Mr Langley on the causes of accidents during the past two decades. The first appeared in the issue of July 18, 1968, pages 101-102, and the second on September 19, pages 433-434. Suitable food which is readily available will always bring in the birds during the daylight hours. Worms, slugs, insects, and grain or fruit will attract them. Birds will follow the plough, and arable land in the immediate neighbourhood of a runway will attract them always, not only during the ploughing but also at the harvest. Field mice and other small rodents may be sought by the larger predatory birds—owls and the like. The presence of water will encourage insects and other bird foods, and provide bankside bushes for nesting places. Any trees or bushes near the runways will give homes for the birds. The ideal landscape in the vicinity of an airport would provide no bird food, nesting places, or water, but to achieve this is hardly ever possible. Neighbouring farmers cannot be told to change from arable to pasture, nor can rivers, ponds, and lakes be altered. Heathrow cannot ask for the reservoirs and gravel pits to be filled in. There will, therefore, always be a bird hazard, though perhaps the flocks will be smaller if they can be discouraged. Worms and insects can be killed chemically, as can small rodents. So could the birds, but this would be unpopular. Much better to bore them. Another method is to scare them away, at least at take-off times—at busy airports, this means all the time. The Canadians report tests on a number of methods of bird- scaring. They have tried shell-crackers with success, and also Very pistol flares. Marine signal rockets are also effective momentarily, but none of these stop the birds returning when the noise dies down and they become acclimatised to such tricks. The Canadian report favours a pyrotechnic device which draws sparkling attention to its arrival before exploding. Tape recordings of bird distress calls when used alone are not as effective as shell crackers. Falcons are not now used since they need full-time trained handlers and are useless at night. Apart from these local conditions at airports, the other danger to aircraft lies in meeting a flock of migratory birds, often at night. The problem is being narrowed by greater knowledge of the migratory pattern, supplied by ornitholo gists and bird watchers on the ground, and by radar plotting. The latter method is particularly valuable since it can be used at night. It seems that the flocks follow barometric pressure patterns which help them on their way. The meteorologists therefore help in forecasting the probable intensity and
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