Authorities believe birds were sucked into the engines of a U.S. Airways A320 that made an emergency landing in the Hudson River after losing power, an incident that underscores the danger small birds pose to low-flying aircraft and the difficulty aircraft engine manufacturers and airports face trying to address it.
All 155 people aboard U.S. Airways Flight 1459 survived after the pilot ditched the plane after losing power in both engines. Investigators trying to determine if, and how, birds were to blame were stymied by the frigid waters of the Hudson River and the fact both engines broke free of the aircraft after the crash and sank.
As our colleague Alexis Madrigal reports, bird strikes are becoming increasingly common, with 7,666 recorded in 2007. Though it might seem implausible that something a bird could take down a 45-ton aircraft, aviation experts say jet engines are relatively delicate. They spin at tens of thousands of revolutions per minute, and their compressor blades are easily damaged. When they go, it's like tossing a hand grenade into the engine.
"Even if one of those things breaks off, the one blade will go through the rest of the engine and it's like shrapnel," Dave Oderman, a professor of aviation technology at Purdue University, told Live Science. Chris Yates, an aviation expert for Janes Information Group, told the BBC, "We're talking about large chunks of metal crashing around inside an engine."
Any bird can cause problems, but experts say Canada geese are among the most dangerous because of their size. According to The New York Times, a 12-pound bird hitting a plane traveling 150 miles carries the same force as a 1,000-pound weight dropped from a height of 10 feet. Although large aircraft are certified to sustain a strike from a four-pound bird, there are more than 36 varieties of fowl that weigh more than that.
Because it is impossible to prevent bird strikes, manufacturers try to ensure that their engines can survive them. Matt Perra of Pratt & Whitney says that engines are fired up during testing and fed all sorts of (already dead) birds, from sparrows to herons, and that batches of birds are sent through the engine simultaneously to simulate a plane passing through a flock.
Airports also do what they can. Air traffic controllers warn departing and arriving aircraft about birds passing through the area, and airport officials have tried everything from loud music and propane cannons to paintball guns and spraying Kool-Aid to repel birds. At Dallas-Fort Worth, Seattle-Tacoma and other airports, radar helps detect birds flying through aircraft arrival and departure paths. "The measures can work around the airport, but planes get out of the airport environment very quickly and conditions can change from moment to moment," University of Illinois professor Ed Herricks told the Chicago Tribune.
That's why despite airports' best efforts, bird strikes remain a problem. More than 200 people were killed and more than 200 aircraft destroyed since 1988 as a result of bird strikes. The deadliest occurred in 1960 when an Eastern Airlines Electra turboprop flew into a flock of starlings at 400 feet, then crashed into Boston Harbor and split in two. Sixty-two of the 72 people aboard were killed.
Strikes have grown more common, too, rising from 1,738 in 1990 to 7,666. Read more about why over at Wired Science.
POST UPDATED 5:20 p.m. PST.
Photo: Ole C Eld / Flickr