For the briefest of moments last week, it looked like the search for MH370 might be over. Sonar images from ocean depths of nearly 13,000 feet revealed "multiple small bright reflections in a relatively small area of otherwise featureless seabed," said Peter Foley, director of the Australian Transport Safety Bureau.

Evidence of any kind of manmade objects delivered a much-needed lift to the team investigating the disappearance of Malaysia Airlines Flight 370, which is nearing the end of a nearly year-long, and thus far futile, underwater quest for the remains of the Boeing 777 and the 239 people aboard. A robot trailing the Dutch ship Fugro Equator was quickly sent back down with a camera. The verdict: This was indeed wreckage, but of a ship—not the plane that vanished without a trace more than 14 months ago.

This was just the latest of many setbacks for ATSB, which maintains that it is more determined than ever to find the missing plane, despite the daunting costs and logistical difficulties. But with so few facts to go on, is MH370 going to turn into modern aviation's version of a cold case?

"Until we find the aircraft, everyone can say, 'Well, you must be looking in the wrong place.'"

"It's been a challenge for months and it's going to continue to be a challenge," said John Goglia, former National Transportation Safety Board member and a safety consultant. But he added that he believes the search can never be officially shut down, even if nothing turns up.

The search slogs on

Investigators have a plan for the short term: At the end of May, when the search of the initial 23,000-square-mile zone concludes, they will reboot the operation and embark on phase 2 to cover 46,000 square miles. That could take another year to complete because winter is about to set in in the Southern Hemisphere, meaning searchers for MH370 are going to be out there for a long time to come even if nothing turns up.

The shipwreck discovered by MH370 searchers ATSB

Oddly, the shipwreck discovery—despite the fact that it was a false alarm—is giving the operation a boost, in part because it affirms how well the technology is working. The pictures were so clear that maritime experts have already determined the vessel dates from the 19th century. However, the vital robot that delivered the data this time is about to be sidelined because of the changing seasons. Team leaders said they can't risk damaging the drone until conditions improve, and without it, the search is clearly going to slow down.

As the search slogs onward, two questions continue to baffle observers and will drive the future of the investigation. One, why hasn't any floating debris turned up? And two, are they looking in the right place.

Debris

First, the debris: Many experts have noted that it's virtually unprecedented in modern aviation to have found not a single piece of a missing plane. Even when jets have crashed in remote sections of the ocean, such as Air France 447 in 2009, fragments were spotted within days.

It's possible something did surface soon after the March 8, 2014 disappearance of MH370, but no one noticed because they weren't looking in the right place. In that case the trash would have traveled far from the crash scene by the time investigators homed in on the current search zone.

It's virtually unprecedented in modern aviation to have found not a single piece

Late last year the Australian team had predicted that it could take a year or more for wreckage to wash up on land, based in part on a drift model that they developed with experts that taps knowledge of ocean currents, winds and weather conditions. The best guess for where the flotsam might surface is the western coast of Sumatra, Australian authorities said at the time.

But Goglia scoffed at the idea that a drift model would accurately predict where debris would end up. In the southern Indian Ocean, "you have these hundreds of tracks just swirling around like a giant whirlpool,' he said. "Just because it's drifting doesn't mean it is drifting toward land." And it's possible that some of MH370 could have mingled with a larger heap of floating garbage somewhere in the sea.

Search zone

The total absence of hard evidence is also leading some to question whether search zone itself is off base. The search team has continued to reaffirm its confidence in the calculations—based on the Inmarsat satellite data and the pings from the errant plane as it headed south—that led investigators to focus on the so-called seventh arc, refining the hunt to an area about 1,000 miles west of Perth, Australia.

But team members also acknowledged that there's room for error. Already, the boundaries of the search area have been tweaked; last fall it was moved 500 miles further south based on adjusted calculations.

"This is so important, not to mention a matter of national pride."

Cold case?

What if the search comes up empty after another year or two—will they just give up? That's highly unlikely, given the high profile of the case and importance of solving aviation's biggest mystery, according to several sources close the matter.

While the costs of the probe are expected to exceed $100 million, it is virtually unprecedented for a search of this magnitude to be called off, at least in the modern jet age, according to a source at the NTSB who preferred to remain anonymous.

"This is so important, not to mention a matter of national pride," he said of the countries involved, chiefly Malaysia, China, and Australia. "It's a big ocean, but I think they will find some wreckage at some point."

Plus, everybody's got their pet hypothesis (or conspiracy theory) about the ultimate fate and location of the plane. There are crowd-funding efforts to fund a search in areas beyond where official investigators are looking, and websites full of rampant speculation and alternate theories. In short, there will never not be somewhere to look.

"Until we find the aircraft, everyone can say, 'Well you must be looking in the wrong place because you haven't found it,'" Martin Dolan, chairman of the ATSB, told Australian news media recently.

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