NEW YORK (AP) — An engine tail cone fell off a Delta Air Lines jet shortly after takeoff Thursday and plummeted thousands of feet before landing harmlessly on a lawn in a Long Island residential neighborhood.

Apparently, neither the pilots nor anyone on the ground immediately noticed the mishap. 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 20-pound cone, measuring 4 feet long and 3 feet in diameter at its widest spot was big enough to kill someone if it hit them from a great height.

It was on the lawn of a home in Roosevelt, N.Y., for several hours before anyone called police. The house is about 90 miles east of Kennedy Airport, where the flight originated.

Delta spokesman Anthony Black said an investigation is under way to determine what went wrong.