Investigators trying to determine how birds could have brought down US Airways Flight 1549 were hampered by the swirling, bone-chilling waters of the Hudson River on Friday as they looked for the plane's two missing engines and tried to retrieve its black boxes.
The investigation ran into a series of obstacles one day after the pilot ditched the plane carrying 155 people into the river following an apparent collision with birds that caused both engines to fail. The jet went down just feet from the Manhattan skyline. All aboard survived.
Both engines broke off the plane sometime after the crash and sank to the bottom of the river, forcing investigators to use sonar to seach for them. The current was especially swift, making it impossible for crews to hoist the aircraft out of the water and remove its flight data recorder and cockpit voice recorder.
Investigators also had yet to interview the pilot, Chesley B. "Sully" Sullenberger.
The pilot's status as a national hero rose by the hour as he took a congratulatory call from the president, earned effusive praise from passengers on the plane and become the subject of a growing global fan club. The pilot was in good spirits and showing no outward signs of stress from the ordeal, a pilots union official said.
Crews planned to pull the plane from the water on Saturday before putting it on a barge.
Investigators want to closely inspect the engine to figure out how exactly the birds caused the plane to fail so badly and so fast. They may also examine any feathers remaining in the engine to determine the type of bird species, helping prevent future mishaps.
The type of engine on the Airbus 320 is designed to withstand a 4-pound bird strike, said Jamie Jewell, a spokeswoman for CFM International of Cincinnati, which manufactures the engines. That's fairly typical for commercial airliners and their engines, although larger Canada geese can exceed 12 pounds.
Kitty Higgins, a spokeswoman for the National Transportation Safety Board, also suggested that part of the investigation will be to "celebrate what worked here," something of a rarity for an agency that focuses on figuring out what went wrong in a disaster.
"A lot of things went right yesterday, including the way that not only the crew functioned, but the way the plane functioned."
The investigation began as new details emerged about why the pilot chose to land the plane in the river - and not at two nearby airports. The pilot twice told air controllers that he was unable to make the proper turn after reporting a "double bird strike."
The tower believed Sullenberger meant that both his jet engines had been damaged by bird impacts.
The accident also raised questions about whether airports around the country are doing enough to deal with bird flocks.
The agency that operates New York City's major airports said it has a multimillion-dollar program to chase birds off its property, but can only do so much to protect planes once they are in the air.
The Port Authority of New York and New Jersey said it kills thousands of birds every year in the marshy waterways and tidal flats that surround its two major airports in Queens, and uses guns, pyrotechnics and hawks to drive away birds.
Among the other tactics: Bird eggs are coated in oil to prevent them from hatching. Nests are removed. The agency also plays recordings of bird distress calls, and landscapers remove any shrubs and trees that might be attractive to certain species.
The Air Transport Association, an airline association, has had a "bird strike" task force for years examining things that can be done to reduce the danger of a hit.
Among other things, the task force has arranged for any feathers collected from damaged aircraft to be sent to a lab at the Smithsonian where they can be analyzed to determine the species involved. Knowing the type of bird can help authorities decide how to control flocks in busy airspace.
The Port Authority could not immediately provide statistics on bird strikes at New York City airports, but pilots appear to report close calls routinely.
Sometimes aircraft have to take evasive action to avoid a flock of geese. Other times, it's too late and they can only hope for the best.
One Boeing 737 pilot writing about a strike in a safety report described the smell of burnt feathers and seabird after a gull was sucked into his rear engine during a landing at LaGuardia in 2004.
If an engine takes in a large bird - or several birds at once - fan blades may break, causing an imbalance in the engine's rotation and severe vibrations, said Kevin Poormon, who tests the ability of aircraft engines to withstand bird strikes. Those vibrations conceivably could be strong enough to cause the engine to come loose from its mounting, Poormon said.
Passengers heaped more praise on Sullenberger, co-pilot Jeff Skiles and their crew for how they handled the landing and evacuation.
Mark P. Hood, of Charlotte, N.C., said he felt a jolt ripple through the jet as though a baseball bat hit the engine close to the George Washington Bridge.
"I think everyone was holding their breath, making their peace, saying their prayers," Hood said.
His wife, in an interview outside their California home, called him "a pilot's pilot" and said talk of him being a national hero was "a little weird."
At a City Hall ceremony Friday to honor those who came to the aid of the stranded passengers, Mayor Michael Bloomberg said Sullenberger's actions "inspired people around the city, and millions more around the world."
Higgins said that investigators will look at his actions in preventing widespread death during the episode.
"It is a very rare event," she said. "Pilots train for this routinely, through the use of simulators. So it's something that they plan for, but not something that is executed with any regularity at all."
Part of the NTSB's job, she said, will be to look at "everything that made yesterday's accident so survivable."
Another possibly helpful factor during a crash is the presence of fuel on board. Jet fuel is lighter than water, and can help make an aircraft more buoyant - as long as it doesn't explode on impact. The air in the cabin also helps the plane float.
The NTSB is working with the FBI and the city to retrieve any video evidence recorded by city citizens. The Coast Guard is trying to ensure that fuel still in the aircraft is contained, if possible, and doesn't spill into the river.
Police and emergency crews also pulled about 15 pieces of carry-on luggage, the door of the plane, sheared pieces of metal and flotation devices from the water.
The plane, bound for Charlotte, N.C., took off from LaGuardia Airport at 3:26 p.m. Thursday. Less than a minute later, the pilot reported a "double bird strike" and said he needed to return to LaGuardia, said Doug Church, a spokesman for the National Air Traffic Controllers Association.
If the accident was hard to imagine, so was the result: Besides one victim with two broken legs, there were no other reports of serious injuries.
Passengers quickly realized something was terrifyingly wrong.
"I heard an explosion, and I saw flames coming from the left wing, and I thought, `This isn't good,'" said Dave Sanderson, 47, who was heading home to Charlotte from a business trip.
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