Jan. 17, 2009 -- A lack of mandatory reporting procedures means no one really knows how many birds strike planes each year and where those incidents occur most often, according to aviation authorities.
Experts said only 20 percent of bird strikes are ever reported, and some airports are more conscientious than others about keeping track of them. This means what data is available may be skewed and thus be an unreliable indicator of which airport and airspaces have the greatest problems with wildlife incursions.
The Federal Aviation Administration maintains a list of bird strikes by airport but when contacted by ABCNews.com, the agency declined to release that information.
Bird strikes are in the public eye after the ditching of US Airways Flight 1549 Thursday in New York's Hudson River because of a bird strike in both engines of the Airbus A-310 jet. All 155 people onboard survived the flight, which originated at New York's LaGuardia airport.
Eastern Region spokesman Jim Peters told ABCNews.com today that the FAA has confidentiality agreements with the airports, the airlines and air traffic controllers. That agreement, he said, allows the FAA to collect information to improve safety and encourages accurate and timely reporting of incidents.
Such confidentiality, he said, means "we don't have to pull teeth to get the information." It also means the public can't get access to some types of safety data.
Archie Dickey, an Embry-Riddle Aviation University professor who prepared FAA's database but was not authorized to release the contents, said there's a feeling in the community that if airports report every bird strike they will be criticized for poor management.
And that makes the airport that does the best job of reporting look like the worst in aviation safety.
Airports are encouraged to report as many incidents as possible, said Sean Broderick, spokesman for the Virginia-based American Association of Airport Executives. But it is completely voluntary.
"Understanding the problem … means understanding what the birds are doing," he said.
According to the FAA, since 2000, at least 486 commercial aircraft have collided with birds, leading to 166 emergency landings and 66 aborted takeoffs.
"Nobody outside the airport or aviation world thinks about this stuff until something happens," Broderick said. His organization represents 850 airports in the United States.
Making the Skies Safer
But airports have undertaken costly efforts to make their runways and surrounding skies safer -- from canons to dogs to specially trained falcons and habitat mitigation.
Orlando International Airport, he said, worked with the University of Florida to remove all the fish from storm water ponds near the airport so larger birds, such as cranes, wouldn't be attracted to the area.
There are some clues to bird strike patterns, however.
"There's more chance of an occurrence of a strike in the eastern part of the country, on the coast," Dickey said.
There are three main flyways in the United States -- routes that migratory birds take to fly south for the winter and north during warmer weather, he said.
One, seemingly the most populous, runs along the eastern seaboard. The other two are on the West Coast and down the middle of the country.
By simple reasoning, Dickey said, planes that fly along these routes increase their chances of getting hit. But unfortunately for East Coast birds and fliers, that area also has the most concentrated air traffic.
The growing population of birds makes the situation worse. While migratory birds used to be the most common cause of aviation hits, the number of resident birds has grown exponentially in the last three decades as larger urban areas provide them with fewer natural predators and more places to survive the winter months -- buildings, golf courses and parks, to name a few.
Dickey said it is estimated that the number of resident birds has increased by 7.3 percent, or several million birds, between 2008 and 2006.
Geese, which were thought to be the species that took down Flight 1549, are in the top 10, he said, of most populous species in the United States.
'Variety' of Ways for Birds to Take a Plane Down
Bird strikes happen every day and can be deadly, with more than 200 people killed since 1988 because of airborne collisions with birds, according to the Bird Strike Committee USA.
"There's a variety of ways a bird can take down an airplane," said John Ostrom of the Metropolitan Airports Commission at the Minneapolis-St. Paul International Airport, who's also chairman of the Bird Strike Committee.
Birds can disable planes, Ostrom said, by flying into the engines and shutting them down. They can also penetrate the windshield or other parts of the fuselage, causing pilots to lose control.
And apparently when it comes to collisions with birds, size doesn't always matter.
"There have been instances where birds the size of robins bring a plane down, all the way up to Canada geese," Ostrom said.
Even when birds don't cause death, injury or drama such as Thursday's Hudson River rescue, they do cost airplane owners money.
The FAAs Web site on Airport Wildlife Mitigation says that bird strikes do more than $300 million of damage to aircraft each year.
While there are wildlife mitigation options for airports, there's not much a pilot can do to avoid birds in the air.
"You're not going to move the airplane like you're moving a car or moving a bike," Ostrom said. "When you're moving something at 100 mph, it's pretty much straight on."