The airplane part that washed up last week on a French island in the Indian Ocean is definitely a piece of Malaysia Airlines Flight 370, Prime Minister Najib Razak of Malaysia said Thursday. The discovery provided investigators and families of the victims with the first tangible trace of the ill-fated flight.
A person involved in the investigation said, however, that experts from Boeing and the National Transportation Safety Board were not fully satisfied that the part had come from Flight 370 and called for further analysis before reaching a definite conclusion.
Their doubts were based on a modification to the part, known as a flaperon, that did not appear to match what they would expect from airline maintenance records, according to the person, who requested anonymity because the person was not authorized to discuss the matter publicly.
French and Malaysian officials did not share the Americans’ hesitation, partly because no other Boeing 777s are unaccounted for.
“The international team of experts have conclusively confirmed that the aircraft debris found on Réunion Island is indeed from MH370,” Razak said in a televised statement broadcast shortly before a news conference on the matter in Paris.
At the news conference, Serge Mackowiak, the deputy Paris prosecutor, said there were “very strong presumptions” that the part belonged to Flight 370, although additional checks would be carried out.
Mackowiak said representatives from Boeing confirmed that the wing flap was from a Boeing 777, based on its size, color, joint structure and other technical characteristics. He also said that “technical documentation” provided by Malaysia Airlines enabled experts to establish “common technical characteristics” between the debris and the flaperons on Flight 370.
He did not mention whether any serial number had been found on the airplane part that might unequivocally link it to the flight.
In any case, experts have cautioned that the discovery of the object was unlikely to tell investigators enough to determine exactly what happened to the plane.
The aircraft vanished with 239 people aboard in March 2014 while on a flight to Beijing from Kuala Lumpur. Less than an hour after takeoff, it veered off its planned route and stopped communicating with ground controllers. Radar data and satellite signals showed that it flew west across the Malay Peninsula and then south over the Indian Ocean, where it is presumed to have run out of fuel and crashed in very deep water, killing everyone aboard.
Months of extensive air and sea search efforts failed to find any trace of the aircraft. Authorities in Malaysia and Australia, which is leading the search, reacted cautiously after the discovery on Réunion, wary of raising hopes after previous false leads.
There was much interest in China, where the authorities struggled in the days after the crash to contain anger among the families of the 153 Chinese citizens who were on board. After a year of searches and false leads, relatives of the passengers greeted news of the discovery of the plane debris with caution. And state news media warned that even if the debris proved to have come from Malaysia Airlines Flight 370, the body of the plane was still missing.
But confidence grew as it became increasingly clear that the object was a part of a Boeing 777 flaperon, a movable section of the wing that helps stabilize the plane while flying at low speeds and during takeoff and landing.
Réunion was thrust into the international spotlight after the discovery, prompting many on the island to scour its beaches for more clues. No other debris has been confirmed as coming from the flight.
Malaysian authorities said last week that they were seeking help from countries near the French island and asking to be notified if debris washes up on their shores. Experts have warned that the complex movements of ocean currents and sea winds over so long a time would make it extremely difficult to trace the debris back to locate other wreckage.
Officials said the piece found on Réunion, made from composite materials with a lightweight honeycomb interior, could float for months, unlike many other parts of the plane, which are likely at the bottom of the ocean.
Australia is leading the underwater search for the plane, while the Malaysian authorities are conducting the broader investigation into the plane’s disappearance. French prosecutors have begun an investigation of their own because there were four French citizens on the flight, and the wing part is being examined in France because it washed up on French territory.
Warren Truss, the deputy prime minister of Australia, said in Sydney on Wednesday that the discovery did not change calculations of where to look for the plane. His country’s national science agency has confirmed that material from the current search area could have been carried by ocean currents to Réunion, thousands of miles west of the remote stretch of deep ocean where the plane is believed to have gone down, Truss said.
Material could also have reached “other locations, as part of a progressive dispersal of floating debris through the action of ocean currents and wind,” Truss said in the statement, which was issued hours before the announcement about the examination of the wing part.
“For this reason, thorough and methodical search efforts will continue to be focused on the defined underwater search area, covering 120,000 square kilometers, in the southern Indian Ocean,” Truss said. That area is equivalent to about 46,000 square miles.
By Wednesday afternoon, the Australian Transport Safety Bureau said that about half the search area — 23,000 square miles — had been combed so far and that there would be a short break in the effort while the two search vessels returned to port for supplies.
In a separate report, also released Wednesday, the Australian science agency said its updated modeling showed that most floating debris from a crash in the search area would probably have drifted north and then west.
Local authorities in Réunion have directed all inquiries about the matter to Paris, but they continue to be deluged with other reports of debris — much of it ordinary flotsam that regularly washes ashore on the island.
Mackowiak, the deputy prosecutor, said that no analysis had yet been done on another object found on Réunion and sent to Paris, which appeared to be the remnants of a piece of luggage.
Réunion rises high from the sea, with an active volcano on one end and a mountain rising roughly 10,000 feet above sea level on the other.
The island’s 130 miles of coastline are dominated by cliffs and rocky shores, making much of the area difficult to search.
After the discovery of the wing part, helicopters were sent to the area, but people involved in the search said it had quickly become clear that such an effort would be of limited value given the vast area where wreckage might be.
Another Malaysia Airlines jet, Flight 17, was shot down over a rebel controlled part of eastern Ukraine on July 17, 2014, killing all 298 people on board.
Last month, Russia blocked a U.N. Security Council resolution that would have created a tribunal to prosecute and punish those found responsible for shooting down the jet, which is believed to have been hit by a missile while flying to Kuala Lumpur from Amsterdam.