New York ? Thick mud, menacing currents and bone-chilling temperatures stymied investigators Friday as they scoured the Hudson River for the two missing engines from a US Airways jetliner that crash-landed in the water after colliding with birds.

The investigation ran into a series of obstacles one day after the pilot ditched the plane carrying 155 people. The collision apparently caused both of the engines to fail, forcing the aircraft to go down just a few hundred yards from the Manhattan skyline. All aboard survived.

Sometime after the plane hit the water, the engines broke off and sank to the bottom, forcing investigators to use sonar to search for them.

Experts said the wreckage could be nearly impossible to find because it is probably 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, one of the groups brought in to help with the search.

The current was especially swift Friday, 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 congratulatory calls from the president and president-elect, 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 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.

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.