SAINT-ANDRE, Reunion — A sea-crusted wing part washed up on an island in the western Indian Ocean may be the first trace of Malaysia Airlines Flight 370 since it vanished nearly a year and a half ago, and a tragic but finally solid clue to one of aviation's most perplexing and expensive mysteries.
Malaysia's prime minister said Thursday the debris found on the French island of Reunion will be sent for investigation to the French city of Toulouse, hub of the European aviation industry.
"We have had many false alarms before, but for the sake of the families who have lost loved ones, and suffered such heartbreaking uncertainty, I pray that we will find out the truth so that they may have closure and peace," Najib Razak said on his personal blog.
Najib promised to make any new information public quickly.
Air safety investigators — one of them a Boeing investigator — have identified the component as a "flaperon" from the trailing edge of a Boeing 777 wing, a U.S. official said. Flight 370, which disappeared March 8, 2014, with 239 people on board, is the only 777 known to be missing.
The piece could help investigators figure out how the plane crashed, but whether it will help search crews pinpoint the rest of the wreckage is unclear, given the complexity of the currents in the southern Indian Ocean and the time that has elapsed since the plane disappeared.
"It's the first real evidence that there is a possibility that a part of the aircraft may have been found," said Australian Transport Minister Warren Truss, whose country is leading the search for the plane in a remote patch of ocean far off Australia's west coast. "It's too early to make that judgment, but clearly we are treating this as a major lead."
Flight 370 had been traveling from Kuala Lumpur to Beijing, but investigators believe based on satellite data that the plane turned south into the Indian Ocean after vanishing from radar. If the wing part is from the Malaysian plane, it would bolster that theory and put to rest others that it traveled north, or landed somewhere after being hijacked.
The wing piece is about 2 meters (6 feet) long. Investigators have found a number on the part, but it is not a serial or registration number, Truss said. It could be a maintenance number, which may help investigators figure out what plane it belongs to, he said.
Flaperons are located on the rear edge of both wings, about midway between the fuselage and the tips. When the plane is banking, the flaperon on one wing tilts up and the other tilts down, which makes the plane roll to the left or right as it turns.
French law enforcement authorities are on Reunion island to examine the piece, according to an official close to an investigation of the debris. A French law enforcement helicopter is scouring the waters around the island in hopes of spotting more debris, and U.S. investigators are examining a photo of the debris.
The wing part was found on a desolate, rocky beach in the small town of Saint-Andre and was transferred to the civil aviation authority's offices in the island's main airport, a local police official said.
The French and U.S. officials spoke on condition that they not be named because they aren't authorized to speak publicly.
France's Foreign Ministry said in a statement Thursday that the piece is currently under the authority of French judicial officials who will cooperate with international authorities investigating the disappearance of MH370.
A massive multinational search effort of the southern Indian Ocean, the China Sea and the Gulf of Thailand has turned up no trace of the plane.
The last primary radar contact with Flight 370 placed its position over the Andaman Sea about 370 kilometers (230 miles) northwest of the Malaysian city of Penang. Reunion is about 5,600 kilometers (3,500 miles) southwest of Penang, and about 4,200 kilometers (2,600 miles) west of the current search area.
It was well understood after the aircraft disappeared that if there was any floating debris from the plane, Indian Ocean currents would eventually bring it to the east coast of Africa, said aviation safety expert John Goglia, a former member of the U.S. National Transportation Safety Board. But the debris is unlikely to provide much help in tracing the ocean currents back to the location of the main wreckage, he said.
"It's going to be hard to say with any certainty where the source of this was," he said. "It just confirms that the airplane is in the water and hasn't been hijacked to some remote place and is waiting to be used for some other purpose. ... We haven't lost any 777s anywhere else."
Reunion authorities have asked France's aviation investigative agency, known as the BEA, to coordinate with international investigators, notably Malaysian and Australian authorities.
The discovery is unlikely to alter the seabed search, said Australian Transport Safety Bureau Chief Commissioner Martin Dolan, who is heading up the hunt. If the find proved to be part of the missing aircraft, it would be consistent with the theory that the plane crashed within the 120,000-square-kilometer (46,000-square-mile) search area, 1,800 kilometers (1,100 miles) southwest of Australia, he said.
"It doesn't rule out our current search area if this were associated with MH370," Dolan told The Associated Press. "It is entirely possible that something could have drifted from our current search area to that island."
Dolan said search resources would be better spent continuing the seabed search with sonar and video for wreckage rather than reviving a surface search for debris if the part proved to be from Flight 370.
Robin Beaman, a marine geologist at Australia's James Cook University, said there is precedence for large objects traveling vast distances across the Indian Ocean. Last year, a man lost his boat off the Western Australia coast after it overturned in rough seas. Eight months later, the boat turned up off the French island of Mayotte, west of Madagascar — 7,400 kilometers (4,600 miles) from where it disappeared.
Beaman believes experts could analyze ocean currents to try to determine where the plane entered the water, though given the time that has elapsed and the vast distance the debris may have traveled, it would be very difficult.
If the part belongs to Flight 370, it could provide valuable clues to investigators trying to figure out what caused the aircraft to vanish in the first place, said Jason Middleton, an aviation professor at the University of New South Wales in Sydney. The nature of the damage to the debris could help indicate whether the plane broke up in the air or when it hit the water, and how violently it did so, he said.
The barnacles attached to the part could also help marine biologists determine roughly how long it has been in the water, he said.
But the sister of a Flight 370 passenger says she is skeptical of the new find.
"It has been more than one year, and now they claim to have found debris of MH370 on an island? We don't accept this. We do not believe what they claim. The finding does not constitute anything," Dai Shuqin told The Associated Press. Her sister Dai Shuling and five members of her family were on the plane.
Over the past 16 months, hopes have repeatedly been raised and then dashed that the plane, or parts of the plane, had been found: Objects spotted on satellite imagery, items found floating in the sea and washed ashore in Western Australia, oil slicks — in the end, none of them were from Flight 370.
The most infamous false lead came in April 2014, when Australian Prime Minister Tony Abbott said officials were "very confident" that a series of underwater signals search crews had picked up were coming from Flight 370's black boxes. The signals proved to be a dead end, with no trace of the devices or the wreckage found.
Kristen Gelineau in Sydney, Rod McGuirk in Canberra, Australia, Joan Lowy in Washington, Lori Hinnant and Greg Keller in Paris and Edith Lederer at the United Nations contributed to this report.