“Without physical evidence, and a reasonable amount of it, there are going to be a lot of loose ends,” said Don Knutson, an aircraft accident investigator. “Enough loose ends where there is going to be a very inconclusive finding.”

Once the debris is found — and aviation experts remain optimistic at least some will be — ships will carefully collect it, tag it, and bring it to a warehouse or hangar, most likely in Australia.

The lightest, most buoyant pieces, such as seat cushions, sections of the fuselage, and the like will most likely float or eventually wash up somewhere. Heavier parts like landing gear, engines, and large sections of airframe will sink, more or less directly below the point at which they hit the water. Locating a debris field will narrow down the search area for these key components, and search crews almost certainly will, as they did with Air France 447, rely on remotely operated submersibles to comb the sea floor. This will be particularly challenging, as the southern Indian Ocean has a volcanic and rugged floor and some of the deepest water in the world. It also is a brutally violent place, rocked by some of the most severe weather on Earth.

Before retrieving anything, recovery personnel will be briefed by Boeing, Rolls-Royce (which manufactured the engines), and others on how to pull up major components and minimize the risk of further damaging them. Once those parts are aboard recovery vessels, they will be treated with solvents to arrest the rapid corrosion that comes with submersion in salt water.