Herb Hunter, spokesman for the United Airlines branch of the Air Line Pilots Association, said the union was happy that the 48 passengers and five employees got off the Airbus A319 "safe and sound." The pilots have not been named.
The frightening episode began Sunday morning as Flight 634 from Chicago to Newark was descending on its runway approach.
Suddenly the plane started rising again and circling the airport, "so we knew something was wrong," said Jim Falk, of Middletown, N.J., who was sitting near the front.
The captain, who sounded composed, announced over the intercom that there was an issue with some of the landing gear on the Airbus A319, passengers said. Then he told them they'd be landing in three minutes — and that they should gird themselves for a crash, Falk said.
When the aircraft landed, part of its belly struck the runway, United spokeswoman Robin Urbanski said, and part of its right wing was damaged.
But the passengers, who cheered and sighed with relief, said the landing seemed controlled, and they praised the skillful pilot.
"It was truly a very nice, smooth landing," said passenger John Wiman, a 51-year-old food service packaging salesman from Chicago. "Very gently, the plane tilted to the right. The engine made contact with the runway. I didn't hear much noise and I didn't see sparks. Other passengers did see some sparks."
It wasn't immediately clear what caused the malfunction, said Urbanski, the spokeswoman for Chicago-based United, a subsidiary of UAL Corp.
The plane was moved early Monday from the runway to a hangar.
Federal Aviation Administration spokeswoman Arlene Salac said investigators from her agency would inspect the plane and interview the pilots. She said no further information would be released until the investigation was completed — something that might take weeks or months.