SYDNEY (AP) — Over the past few days of the endlessly perplexing hunt for Malaysia Airlines Flight 370, much debate and confusion has swirled around what was once dubbed the most promising lead in the search: a series of underwater signals, or “pings,” picked up by sound-detecting equipment scouring the remote Indian Ocean in early April.

At the time, officials said they were consistent with a plane’s black boxes. But an underwater sub that spent weeks scouring the seabed in the area near where the signals were detected found nothing, and the Australian Transport Safety Bureau, which is helping head up the search, this week ruled the area out as the plane’s final resting place.