WASHINGTON (CNN) -- A passenger sitting at the rear of the US Airways flight forced to land in the Hudson River testified Tuesday he climbed over about a dozen rows of seats as he tried to escape through the front of the floating plane.
Capt. Chesley "Sully" Sullenberger testifies in Washington about landing in New York's Hudson River.
Billy Campbell is the only passenger scheduled to testify before an aviation safety panel chaired by Robert Sumwalt, vice chairman of the National Transportation Safety Board.
Tuesday was the first of three days of hearings, which will try to determine the probable cause of the January 15 accident, he said.
A final determination will be made by the entire NTSB board.
"I am committed to an impartial and complete investigation of this accident," Sumwalt said at the opening.
Also on the board are two deputy directors: John DeLisi from the Office of Aviation Safety and Joseph Kolly from the Office of Research and Engineering.
The plane's pilot, Capt. Chesley "Sully" Sullenberger, was forced to land the Airbus A320 after both of its engines failed. Officials almost immediately blamed it on birds, probably Canada geese, being sucked into the engines.
Monday, Smithsonian Institution scientists said analysis of feathers found in the engines showed that at least three Canada geese were involved.
All 155 people aboard were safely evacuated after the plane skidded to a stop in the river.
Sullenberger, the hearing's first witness, recommended that training in water landings be mandatory for all pilots. Watch Sullenberger describe the river landing »
Campbell, who was in seat 25A, a window seat, was asked to detail what happened before and after landing.
He testified he heard a loud explosion about three minutes after takeoff. The plane "shuddered," there was a smell of jet fuel, and the left engine was on fire, he said. One passenger tried to get something from an overhead bin but was ordered to sit down by a flight attendant.
He hoped the plane would make it to an airport, but it became evident they were descending over the river. Watch as gripping plane audio is played during the hearing »
"Captain Sullenberger comes on and says brace for impact," Campbell said. "I knew we were going to crash into the river, because I was near the window."
Campbell said that once the plane hit the river, water streamed in from his and other windows, and water from elsewhere began filling the aisle. He said he was unable to dislodge the life vest from under the seat.
Flight attendant Doreen Welsh told passengers in the back that they could not go out the back door and ordered them to "turn around and go to the front." Campbell said he didn't know why the door wouldn't open.
Once the plane struck the Hudson River between New York and New Jersey, "I think our biggest fear was how long would the plane stay afloat," Campbell said.
When they landed, the pilot lifted the nose of the plane, and water poured into the aisles.
"I did see the plane submerge; we were under water," Campbell said. "Then the plane bounced back but started to lift to the right." He said he didn't know the left engine was sheared off. He feared they would tip over.
After being told he couldn't go out the back door, he began climbing over seats to reach the front. At one point, he helped a woman and child who were trying to flee.
He, Sullenberger and the co-pilot got on a rubber raft, but it was tethered to the plane. A crew member from a rescue ferry threw them a knife so they could cut the cord, Campbell said.
Campbell was asked whether he had read the safety card in the seat pocket in front of him, and he said he hadn't, because he flies so much. He said that when the pilot told everyone to "brace for impact," he knew what that meant because he'd seen the order in movies.
"I think a lot of us are unclear about the definition of that term," he said.
A technical panel providing expertise to the board includes Robert Benzon, hearing officer and investigator-in-charge of the crash. Also in the audience were representatives of the Federal Aviation Administration, the Air Line Pilots Association, the Association of Flight Attendants, US Airways, Airbus and CFM International. All were allowed to question the witnesses.