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The statistics of the German Bird Strike Committee show that 69 bird strikes
were caused by collision with Common Swifts (Apus apus) worldwide in the years
1997-2001. The term “worldwide” in this case means that aircraft with a German
licence were involved. 47 of these bird strikes took place in German airspace,
but the German committee has no knowledge of how many strikes by Common Swifts
involved airplanes flying with a foreign licence.
We assume, however, that Swifts were involved in more strikes than is currently
recognized, because species are identified in only about 30-50 % of all bird
strikes. Furthermore, an unknown number of bird strikes involving smaller birds
are not recognized as bird strikes and so are not included in the statistics at
all.
Generally one can say that the Common Swift, like Swallows or other birds that
feed on airborne insects and therefore hunt in restricted thermal influenced
airspace, often above heat-reflecting materials like concrete, are more exposed
to bird strikes than those species that feed on the ground or in water. However,
in relation to their numbers, dead Swifts are rarely found at airports, probably
because of the extraordinary manoeuvrability of this species. In addition their
morphology, with narrow wings, a small and relatively compact body, and short,
highly efficient tail-feathers, makes them less vulnerable to turbulence, so
that, unlike more sluggish birds, they do not often die in the slipstream of
aircraft. These factors help reduce the theoretically higher rate of losses from
direct collisions with aircraft.
Dr. C. Morgenroth is manager of the German Bird Strike Committee (GBSC)
Deutscher Ausschuss zur Verhütung von Vogelschlägen im Luftverkehr e.V.
www.davvl.de
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