Federal investigators are pursuing early indications that the US Airways jet that crash-landed in the Hudson River was struck by geese shortly after taking off — a type of collision that has caused problems for pilots since soon after the first airplane flight.
The accident involving the jet, which took off from La Guardia Airport, would be unusual, though, because both of the plane’s engines appeared to have been damaged by birds, aviation experts said on Thursday.
Since 2000, at least 486 planes have collided with birds, according to the Federal Aviation Administration. Of those incidents, 166 led to emergency landings and 66 resulted in aborted takeoffs.
The earliest known fatal airplane crash involving a bird took place in 1912, nine years after the first flight by the Wright Brothers at Kitty Hawk, N.C. That plane crashed into the surf off Long Beach, Calif., pinning its pilot under the wreckage.
The most deadly crash involving a bird strike occurred in 1960, when 62 people were killed on an Eastern Air Lines propeller plane that crashed upon takeoff from Boston. That plane collided with a flock of starlings, sucking the birds into three of its four engines, causing the plane to stall and plunge into Boston Harbor.
In the New York area, the most recent incident took place at Kennedy Airport in December 2006, when a great blue heron was drawn into the engine of a Boeing 767 jet shortly after takeoff. The plane returned to the airport, and passengers were put on another flight.
There was another incident at La Guardia as recently as 2003, when an American Airlines Fokker 100 plane hit a flock of geese upon takeoff, causing the right engine to fail. The flight was diverted to J.F.K.
All commercial airplane engines are required to pass a “bird strike” test before they can be certified for use. Engine manufacturers, including CFM International, which produced the engines on the US Airways Airbus A320 involved in Thursday’s sudden landing, test the engines physically and through computer simulation.
In the physical tests, the engines are revved to full power inside a test facility and absorb various kinds of birds, from those the size of sparrows to those the size of herons, one at a time. (The birds are already dead.) The engines also ingest multiple birds meant to simulate a collision with a flock, said Matthew Perra, a spokesman for the engine manufacturer Pratt & Whitney.
To pass the test, engines must keep operating after the collision, maintaining enough power to take off, fly around the airport and land the plane safely, he said. That is because a jet with two engines has to be able to take off on 50 percent power.
Engines are tested one at a time, so manufacturers cannot measure what would happen if a flock of birds hit both engines at once. However, they do study that situation through simulation tests.
“It’s a rare thing to see two engines go out at the same time,” Mr. Perra said.
Airports around the world have encountered bird collisions through the years, making them a standard hazard for commercial, military and private pilots alike.
“Any time you get an open field and grass, you’ve got birds,” said Robert W. Mann Jr., an aviation industry expert in Port Washington, N.Y. Mr. Mann said birds pose the greatest threat during takeoff, when jets use the most engine power in order to become aloft. Birds are also a hazard as the planes climb to cruising altitudes.
Bird strikes are frequently reported around 8,000 feet, especially during migration periods.
Although birds generally do not fly higher than 12,000 feet, there has been a report of a bird strike at 37,000 feet.
New York’s airports are particularly vulnerable to ocean-loving birds, according to Susan Elbin, director of conservation at New York City Audubon. Indeed, there are colonies of gulls on islands adjacent to J.F.K.
For years, the F.A.A., the Port Authority of New York and New Jersey and the United States Department of Agriculture have tried “to minimize the conflict between birds and planes,” Ms. Elbin said. Falcons, along with pyrotechnics, recordings of wild animals and propane cannons that create loud, startling noises, have been used to scare bird populations away from runways.
But sometimes, the airports have been forced to relocate the flocks, or in the most extreme cases, kill them.
“As a last resort you have to do lethal control to convince the rest of the flock that we mean business,” said Russell DeFusco, a member of the steering committee for Bird Strike Committee USA, a group that collects data on bird strikes.
Mr. Mann said pilots can do only so much to train for a possible bird strike. He called the response by the US Airways crew to the emergency “just remarkable.”
Said Mr. Mann: “It was a great piece of flying, both for putting it down where they would not endanger a lot of people, and for putting it down in one piece.”
This article has been revised to reflect the following correction:
Correction: January 19, 2009
An article on Friday about bird-plane collisions, believed to be what led a US Airways jet to crash-land in the Hudson River, misstated the year of the deadliest crash involving a bird strike and, because of an editing error, referred incorrectly at one point to the type of plane involved. The crash, involving Eastern Air Lines, occurred in 1960, not 1962. And as the article noted elsewhere, the aircraft was a propeller plane, not a jet.