The Malaysia Airlines plane that vanished from the skies one year ago Sunday with 239 people on board remains the greatest commercial aviation mystery ever.
Not a single scrap of debris has been found despite a non-stop search along the depths of the southern Indian Ocean, where authorities believe the airliner crashed after it ran out of fuel. But evidence of the plane's route is so scant that even the suspected crash region could be off the mark.
And without any evidence of a crash, some relatives of the lost passengers cling to faint hope that the plane will yet be found with the passengers alive.
"The reality is there's no proof they're dead or that the plane crashed," said Sarah Bajc, a U.S. citizen whose partner Philip Wood, 50, an IBM executive from Texas, was the only American on the flight.
Flight 370 disappeared while en route from Kuala Lumpur, Malaysia, to Beijing on March 8, 2014, with no signals or warnings of anything wrong. Air traffic controllers didn't even know where it went. Radar and satellite data suggest it veered west off course and then south toward the Indian Ocean.
In late January, the Malaysian government declared that the plane was lost in an accident with no survivors, a move that allows families to receive death benefits. The same officials will release an interim report Saturday, one day before the anniversary, yet little new information is expected.
"Not knowing is not an 'accident.' They've taken the easy way out," said Bajc, 49, a former Microsoft executive now based in Kuala Lumpur. "It's still a possibility it's at the bottom of the Indian Ocean. I just feel it's a very remote possibility ... and based on very circumstantial evidence," she said. "In every other crash, there's always been debris."
Bajc continues to press the Malaysian government for more information and even just a meeting, but "they avoid us like the plague." She said family members have various theories, such as the plane was kidnapped or accidentally shot down, and that is being covered up.
"If people were being held, we would have expected to hear about it. That's what most dashes my hope," she said about a possible kidnapping.
So far, the sonar search of the ocean floor hasn't found anything appearing to be debris from the airliner, said Dan O'Malley, spokesman for the Australian Transport Safety Bureau, which is leading the search.
Some observers have questioned whether satellite pings from the plane during its flight really point to where it went down. But O'Malley said the search area was identified after "many months of work with independent experts who reviewed the satellite data and then identified possible 'splashdown points,' " he said. "We remain confident that we are searching in the right area."
Cyclones and bad weather have occasionally hindered the search, but the team is now hustling to take advantage of comparatively calm weather before the region's winter sets in, O'Malley said.
Four ships are currently deploying submersibles with sonar to scan for any sign of debris. So far they have scoured more than 10,000 square miles, an area nearly the size of Massachusetts, the Australian bureau announced Thursday.
The goal is to search a total of 23,000 square miles — the size of West Virginia — by May, This underwater phase at depths of nearly 4 miles is projected to cost up to $60 million, which the Malaysian and Australian governments are splitting.
The hunt cannot go on forever, Australian Transport Minister Warren Truss told Reuters this week. He said a decision must be made soon whether to abandon the search or expand it to an even more vast area.
Ocean searches can take years. Air France Flight 447 from Rio de Janeiro to Paris crashed into the Atlantic on June 1, 2009, with 228 people on board. Floating debris was found after a few days, but it took another two years before locating the wreckage and recovering the "black boxes."
"I don't think they're going to stop, even if they fail to find the aircraft in the next few months," said Al Diehl, a former investigator with the National Transportation Safety Board and author. "There's a potential cloud over the (Boeing) 777 — until we find the wreckage."
The Boeing 777 remains a popular and reliable plane for longer flights, with 1,200 of them flying worldwide. Boeing, airlines and government regulators want to know why Flight 370 disappeared, whether a mechanical malfunction or human error, to help prevent future crashes.
"It's got a tremendous safety record, but we need to find the wreckage to see if there is anything wrong," Diehl said. "There have been a couple of incidents that were really quite scary."
In July 2011, an EgyptAir Boeing 777 had a cockpit fire while parked in Cairo. All 317 people aboard got off safely. The incident led Boeing to study whether oxygen hoses caught fire when exposed to an electrical short-circuit. The problem was fixed.
In August 2005, a a Boeing 777 flying from Perth, Australia, to Kuala Lumpur unexpectedly climbed 3,000 feet while losing speed. The pilots turned off the autopilot, and the plane again climbed 2,000 feet before the pilots manually flew safely back to Perth. The 777's navigation software was reprogrammed to fix it.
With Flight 370, more than 20 relatives from mainland Chinese traveled recently to Malaysia to lobby authorities ahead of Sunday's anniversary, when memorials are planned in both Kuala Lumpur and Beijing.
"We are so angry with the Malaysian government and Malaysia Airlines. They are so evil. They are hiding the truth and have no mercy at all," said Li Shupin, whose only child Li Wenbo, 29, was on the plane.
Her father is among the relatives still waiting in Kuala Lumpur. They continue their protests and public prayer sessions — a year after the plane mysteriously disappeared.
Jansen reported from Washington, MacLeod from Beijing. Contributing: Sunny Yang in Beijing
