The Search For The Missing Malaysia Airliner Is Officially Back To Square One

Pool/Getty ImagesFour acoustic pings emanating from the Indian Ocean thought to be from the missing Malaysia Airlines Flight 370 came from some other man-made source unrelated to the plane, a U.S. Navy official told CNN on Wednesday.

"Our best theory at this point is that (the pings were) likely some sound produced by the ship ... or within the electronics of the Towed Pinger Locator," Michael Dean, the Navy's deputy director of ocean engineering, told CNN.

With searchers pinning their hopes on signals they were "very confident" were from the plane's black box, the revelation is a huge setback, especially considering the battery life of the black box has long since expired.

So far, searchers have scanned 329 square miles of ocean floor with no sign of wreckage, according to CNN.

Searching in the Indian Ocean, Australian Navy vessels had picked up on a number of signals it detected in April, leading officials to believe they were getting closer to finding the plane.

"Despite the lack of further detections, the four signals previously acquired taken together constitute the most promising lead we have in the search for MH370," Angus Houston, the Australian search chief, told Reuters at the time.

The plane, which was carrying 239 people, disappeared on Mar. 8 after losing contact about two hours after takeoff, according to The Mirror.