NEW YORK - AN ENGINE tailcone fell off a Delta Air Lines jet shortly after takeoff on Thursday and plummeted thousands of feet before landing harmlessly on a lawn in a Long Island residential neighbourhood.

Apparently, neither the pilots nor anyone on the ground immediately noticed the mishap when it happened. The aircraft, a Boeing 777, doesn't need the part to fly and carried on safely to its destination, Tokyo, aviation officials said.

Delta personnel reported the engine part missing following an inspection after the plane landed following its 14-hour flight, Federal Aviation Administration spokeswoman Arlene Salac said.

The 9kg cone, measuring 1.2m long and 1m in diameter at its widest spot was big enough to kill someone if it hit them.

It was on the lawn of a home in Roosevelt, New York, for several hours before anyone called police. The house is about 15.3km east of Kennedy Airport, where the flight originated.

Delta spokesman Anthony Black said an investigation is under way to determine what went wrong. He said he was unaware of any similar problems involving Boeing 777s in Delta's fleet. A Boeing spokesman said she had no information about the accident. -- AP