The longest hunt for a missing aircraft in modern aviation history was called off after it failed to produce any results.
Investigators from Australia, Malaysia and China announced on Tuesday that they were calling off the three-year search for Malaysian Airlines Flight 370.
The fruitless investigation started after the aircraft mysteriously disappeared on March 8, 2014. The Boeing 777 was on its way from Kuala Lumpur to Beijing with 239 people on board.
From satellite data, authorities know that the plane flew for one hour until it disappeared from radar. After flying for about six hours, authorities believe the plane plummeted 25,000 feet per minute and landed somewhere in the southern Indian Ocean.
But after years exploring a 46,000-square-mile area, authorities are no closer to piecing together the mystery of the disappearing jet. The underwater search has been called the “largest and costliest” in aviation history.
“We remain hopeful that new information will come to light and that at some point in the future, the aircraft will be located,” transportation ministers said in a joint statement.
Australian investigators valued the three-year investigation at $135 million.
The first piece of debris from the plane washed up on Reunion Island in July 2015. Since then, four more pieces were found on Africa’s eastern seaboard. Authorities have not found any trace of the people on board—not bodies, luggage or even life jackets designed to float.
Although the cause of the crash is still unknown, investigators have several theories. Some believe the plane ran out of gas while others believe pilots attempted an emergency landing at sea. Others suggest that a pilot went rogue or the plane was hijacked.
In February 2016 when the investigation was in danger of being shut down after two years, Martin Dolan, head of the Australian Transport Safety Bureau, spoke about the quest for information.
“There’s always this question: Have we missed something?” he told Bloomberg.