NEW YORK (AP) -- An emergency slide fell off a Delta Air Lines jetliner shortly after takeoff Friday from New York, and pilots who felt a vibration in the plane circled back to land safely at JFK Airport.

Delta said that after takeoff the pilots got an alert about the emergency slide on the plane's right side and heard an unusual sound coming from that area of the Boeing 767 jet, which is listed as having been manufactured in 1990.

The Federal Aviation Administration said the crew reported a vibration.

Pilots declared an emergency so the flight could be be routed quickly back to the airport, and the plane landed and taxied to a gate under its own power, according to the airline.

There were 176 passengers, two pilots and five flight attendants on board the flight, which was scheduled to fly to Los Angeles. Delta said it put passengers on another plane to California.

Delta said the plane was removed from service for evaluation and it was cooperating with investigators and supporting efforts to find the slide.

"As nothing is more important than the safety of our customers and people, Delta flight crews enacted their extensive training and followed procedures to return to JFK," the airline said in a statement.