ONE of the scarier videos on YouTube (ow.ly/sBIOq) was recorded by the nose-cone camera of a fighter jet as it was taking off. Just after the plane leaves the runway a large bird comes hurtling towards it and vanishes into the aircraft’s engine. The pilot spends an agonising 30 seconds or so trying to regain control, before issuing the order to eject, after which the viewer is treated to a shot of the onrushing ground before the screen goes blank.
Bird strikes are a problem–sometimes a fatal one–for military and civil aviation alike. America’s Federal Aviation Administration (FAA) reports that there are about 10,000 such strikes a year to the country’s non-military aircraft, costing more than $US957m in damage and delays. The worldwide figure is estimated by the European Space Agency to be $US1.2 billion.
Moreover, though relatively few people have been killed in accidents caused by bird strikes (research by John Thorpe, former chairman of the International Bird Strike Committee, recorded 242 deaths between 1912 and 2004), the potential for something horrible to happen is real–as was shown by one of the most famous strikes of recent years. In 2009 an Airbus with 155 people on board hit a flock of geese when it was taking off from LaGuardia airport in New York. The passengers were saved only by the skill of the pilot, Chesley Sullenberger, who managed to ditch the plane safely in the Hudson river.
At the moment, attempts to deal with the problem mostly involve efforts to cull flocks of the larger species–geese in particular–in the vicinity of airports, and also the use of bird scarers to try to drive off those actually sitting near runways. As the figures suggest, these approaches do not work well. There may, however, be a better way. For a decade or more the air forces of several countries have used radar to track birds which might threaten their aircraft. Now, similar systems are being considered for civilian airports. If they work, the old methods of trying to scare birds away, or cull them, can be abandoned.
A bird in the band
The longest-running study of the use of radar to prevent bird strikes was started three decades ago, in Israel, by Yossi Leshem of Tel Aviv University. It has helped the Israeli air force reduce the number of strikes it suffers by two-thirds.
Dr Leshem began his research using a mixture of powered gliders, drones, ground-based bird watchers and radar to build up data on the flocks that migrate over Israel in the spring and autumn.
From these observations he has worked out the meanings of different sorts of radar blips, and can thus tell what is going on ornithologically from radar alone.
The upshot is a system which can follow individual birds that weigh as little as ten grams and are as far away as 20km (12 miles).
He can track birds the size of pelicans and geese at a distance of 90km. Moreover, knowledge of the weather, and of how birds have behaved in previous years, allows him to predict what they will do next, so aircraft can be routed above them.