Searchers' frustration over Malaysia Airlines Flight 370 is difficult to overstate, from the monstrous waves that battered search crews in one of the world's most desolate stretches of ocean to the dearth of information on the plane's flight path that stymied investigators. And now, perhaps most brutal of all, comes the admission of defeat.

Australia's announcement on Tuesday that the fruitless, nearly three-year hunt for the plane in the Indian Ocean was officially suspended has sparked the inevitable second-guessing of those who led the $160 million search. Few know the agony surely being felt by the Flight 370 search crew better than American oceanographer David Gallo.

Back in 2010, Gallo and his team from the Woods Hole Oceanographic Institution in Massachusetts were given a task: They had two months to help find Air France 447, which crashed into the Atlantic Ocean in 2009 during a flight from Rio de Janeiro to Paris.

When they didn't find it by the deadline, officials halted the search. Gallo was sick over the failure, couldn't sleep, stared at pictures on his desk of the people who had been on board the plane. He was tortured by self-doubt, wondered if they had somehow missed the aircraft.

"It was horrible," he remembers. "The families were disappointed in a big way, the companies involved — Airbus, Air France — were wondering what had happened ... wondered who are these guys who claimed they could find it and didn't?"

After a year of lobbying, officials agreed to let Gallo and his crew look again. They found the plane in just over a week.

Much like the Flight 370 investigators, Gallo and his team were initially accused of not knowing what they were doing, of misreading data, of using the wrong equipment. But Gallo, who has been in close contact with the Australian search officials leading the hunt for Flight 370, feels confident they have done everything they could, given the limited data available.

Recently, investigators reanalyzed all the information available on the Malaysian plane and suggested that crews scour a new area north of the 160,000-square kilometer (46,000-square mile) search zone they just finished combing. Australia's government nixed that idea, but Gallo says it is imperative crews be allowed to do so.

"If you finish that area, you can say with good conscience, 'We did everything we could do at the time to try to find that plane,'" he says. "But if they don't do that area, it will always haunt us. Forever."

And there is a crucial need to find the plane, he says, for so many reasons.

Gallo still thinks about the people who lost their lives on Air France 447. He lives in coastal Massachusetts, where he often watches planes heading out over the Atlantic on journeys from Boston to Europe. He thinks of the passengers on board, each of them with loved ones back at home.

Their safety weighs on him. And it's one of the major reasons he feels it's crucial to find Flight 370 — for the security of everyone who flies, and for the families of those on board the doomed plane.

"Those 239 people with their loved ones, they just vanished without a trace. So what price do you put on that?" he says. "And then the flying public ... until we know what happened there, it could happen to any of us."