AN AIRBUS A320-231: A US Airways A320 at San Diego Airport
David Mueller, via Wikimedia Commons

US Airways Flight 1549 took off from La Guardia Airport in New York City at 3:03 P.M. Eastern time on its way to Charlotte, N.C., with 150 passengers and five crew members on board. As it gained altitude, it reportedly ran into a "massive flock of birds," according to The New York Times, and the jet engines began making noises—and lost power.

Heading north without engine power, the pilot of the Airbus A320 changed course and—in what some are describing as a heroic but calm act—glided to a watery landing in full view of buildings on Manhattan's west side. "The pilot got on and said, 'You guys got to brace for a hard impact,'" passenger Jeff Kolodjay told the Times. "That's when everyone started to say their prayers. I got to give it to the pilot, he did a hell of a landing." When the pilot, Chesley Sullenberger, emerged from the plane, he had not even donned a life vest, according to the Times of London.

A flock of eight-pound (3.5-kilogram) geese had apparently brought down a plane, plunging it and 155 people into the frigid waters of the Hudson River.

A group of rescue boats soon plucked shivering passengers from the wings. They have been taken to area hospitals, and only minor injuries have been reported so far.

But not every bird-struck flight has been so lucky. The first fatal strike was recorded in 1912, just nine years after the Wright Brothers first flight in Kitty Hawk, N.C. The space shuttle Discovery pulverized a bird during a launch in 2005, although no damage to the spacecraft was recorded.

With soaring air traffic and migratory birds recovering from DDT and other pesticides, the number of bird strikes has been rising over the last 20 years, from about 1,500 in 1990 to about 8,000 last year.

In Thursday's crash, investigators believe geese may have been sucked into both engines during take-off, an unusual situation that is simulated, but not tested, during "bird strike" certifications by aircraft engine manufacturers.

To find out more about the dangers of bird strike, we spoke with Richard Dolbeer, a wildlife biologist and expert on bird strikes who retired in September after working 36 years for the U.S. Department of Agriculture in Sandusky, Ohio.

[An edited transcript of the interview follows.]

Why are birds such a threat to aircraft?
It basically comes down to the physics equation for kinetic energy: Energy is proportional to mass times velocity squared. The velocity of the aircraft allows for the impact of this feathered bird to generate enough force to cause an engine to malfunction. (A 12-pound, or 5.5-kilogram, Canada goose struck by an aircraft traveling 150 miles, or 240 kilometers, per hour at liftoff generates the force of a 1,000-pound, or 455-kilogram, weight dropped from a height of 10 feet, or three meters, according to Birdstrike USA.—Editor's Note)

When a plane is taking off, it is going 170 miles (275 kilometers) per hour  and accelerates to several hundred mph. The engine's fan blades during taking off—like this plane today—are going 3[,000] to 4,000 rotations per minute, and the tips of those turbofan blades are actually at the speed of sound or greater—700 to  800 mph (1,125 to 1,285 kilometers per hour). When a bird hits one of those fan blades, there's a tremendous energy transfer from the bird to the engine, and that's basically why a bird can cause serious damage to an aircraft engine.

We do know that for this flight today, Canada geese would be the most likely species. They typically weigh eight to 10 pounds (3.5 to 4.5 kilograms). They are a large bird so you can imagine the force that's generated.

What is the typical outcome of a bird strike?
Since 1990 the FAA (Federal Aviation Administration) has compiled statistics on bird strikes. I'm the author of a report showing that 12 percent to 15 percent of the strikes result in some damage to aircraft. In the majority of strikes, 85 percent or more, nothing happens: The bird bounces off the plane or a small bird…just goes through the engine and there's no discernible damage [to the plane]. In a small percentage you get damage, and in a smaller percentage you get catastrophic damage.