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Why Hudson River-Like Plane Crashes Will Happen Again

Yesterday's aircraft crash in the Hudson River may have been miraculous in terms of survivability, and it boosted the standing of Twitter, which got stunning images in circulation before the mainstream media. But its suspected cause—birds impacting the plane shorty after take-off—is going to continue to be a problem for aircraft everyday, everywhere around the world.

According to early FAA reports, the US Airways Airbus A320 hit a flock of birds (possibly geese) after taking off from La Guardia at 3.26 EST, resulting in flame-outs of both its engines. Damage to the aircraft's airframe wasn't severe, it seems, and former fighter pilot Chesley B. Sullenburger III was then able to bring the aircraft to a safe water crash-landing with all 148 passengers, two pilots and three cabin staff surviving the impact.

A bird-strike of this magnitude, with both engines apparently suffering damage and rendering the airframe unflyable, is astonishingly unlucky. But since day one of manned flight bird strikes have been causing damage to aircraft and knocking them out of the sky. Check out this video of a fighter plane: immediately after take-off a bird is ingested into the single jet engine, disabling the aircraft and requiring the pilots to eject.

And this video shows the dramatic impact of a large bird into a prop-driven aircraft as it approaches an airstrip. In this case the airframe and pilots survived—but if the bird had hit just a few feet to the right it may have smashed into the cockpit, with a totally different outcome.

Many different measures are put in place at airfields around the world in an attempt to reduce the chances of bird-strikes. Sometimes these are subtle, such as adjusting the terrain on an airfield to reduce its attractiveness to birdlife—removing potential food sources and roosting places. In other cases bird-scaring techniques include detonating pyrotechnic charges to frighten the animals away, flashing bright lights and remote-controlled aircraft. Broadcasting recordings of distress bird calls, "scary" sounds and predator bird calls across the airstrips is a common technique.

J.F.K Airport famously uses a falcon to simultaneously hunt and scare birds on the airport grounds, and other airfields use models of predator birds to scare real animals away. NASA uses many of these techniques to lower the danger at its launch pads, but that doesn't mean there aren't occasional impacts—most famously with a vulture during a Space Shuttle launch in 2006.

But it's completely impossible to 100% remove the bird threat at airports. And this is obviously even more the case for aircraft encountering birds well away from airfields. Birds will continue to fly wherever they wish, despite our best efforts to scare them away from sensitive areas. It's just a question of sharing their airspace—avoiding common migration routes, and bird-populated altitudes for example—and designing aircraft so that they can withstand bird impacts more successfully.

Aircraft windscreens and jet engines are actually designed and tested (using NASA's famous "frozen chicken gun," for example) to withstand bird impacts. Turbofan engines should be able to suffer bird-strike turbine failures at operating speeds without disastrously throwing blades outside the chassis (the image shows blade damage to a Rolls Royce Trent engine under test.) Yet even with careful design, engines are unlikely to survive ingesting a large bird unscathed, which seems to be the case in the US Airways crash.

In short, bird-strikes will continue to happen—we've just got to design aircraft properly and hope that they'll have an outcome as lucky as yesterday's.

[via CNN]