Divers and sonar operators hunted for two sunken engines from a US Airways jetliner in challenging, nearly impossible conditions as investigators made plans to carefully hoist the damaged plane from the water.

The engines, lost when Flight 1549 splashed down after colliding with birds, were presumed to have been carried off by the river's strong tides.

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Exactly where, though, remains a mystery. U.S. Army Corps of Engineers vessels and city police department boats are to resume the search Saturday, probing the sediment-obscured riverbottom along a 4 1/2 mile stretch from the point of impact to the southern tip of Manhattan.

Investigators also planned to conduct their first interview Saturday with the pilot, Chesley B. "Sully" Sullenberger, who slipped the crippled aircraft into the river when he couldn't make a nearby airport, saving the lives of all 155 people aboard.

Authorities want to closely inspect the engines 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.

Thick mud, swift tides and bone-chilling temperatures stymied investigators Friday as the probe began. The current was especially strong Friday, making it impossible for crews to lift the aircraft out of the water.

Authorities said they planned to extract the aircraft Saturday with a pair of cranes and put it on a barge, where it can be inspected.

Experts said the wrecked engines could be far tougher to recover.

They could be 30 to 50 feet down, stuck in mud and obscured by thick sediment. Conditions are so murky that police and fire department divers will have to feel about by hand.

"There is hardly anything to see because of the sediment," said Thomas M. Creamer, chief of the operations division of the New York District of the U.S. Army Corps of Engineers.

Two Army Corps survey boats began searching for the engines Friday, one working south from the crash site, the other heading north from lower Manhattan.

Under the direction of the police department, the National Oceanic and Atmospheric Administration used sonar to look for the engines. That technology can produce a more vivid picture of the riverbottom, but its range is limited.

"It is going to take time," Creamer said. "It is a large area. Things move around quickly."

Meanwhile, the pilot's status as a national hero rose by the hour as he took a congratulatory call from the president and President-elect Barack Obama, earned effusive praise from passengers on the plane and become the subject of a growing global fan club.

Sullenberger was in good spirits and showing no outward signs of stress from the ordeal, a pilots union official said.

The type of engine on the Airbus 320 is designed to withstand a 4-pound (2-kilogram) 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 (6 kilograms).

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.

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.

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."