Everything We Know About MH370 in 170 Seconds

[Narrator] It's been two years

since Malaysia Airlines flight 370 disappeared.

The largest and most expensive search operation

in human history hasn't turned up any helpful clues

about where the plane and its 239 passengers may be

or what happened to them.

We only have one confirmed piece of wreckage.

In July of 2015, part of the Boeing 777's wing

washed ashore on Reunion Island,

450 miles east of Madagascar.

Because it spent 500 days floating around in the ocean,

all it tells us for sure is the plane landed in water.

Thanks, wing flap.

The near-total lack of hard evidence

has encouraged some pretty wild theories:

a fire in the cockpit knocked out the pilots; no.

Russian special ops pulled off

a daring air heist; scratch that.

The military, the US military, shot it down

and hid the evidence.

The plane is in Pakistan.

Nope, you're all wrong.

MH370 got sucked into a black hole.

Okay, that last one's not possible,

but there's no way to know anything

until we find a lot more debris or the black boxes.

For the first few days after MH370 disappeared,

the search centered on the Gulf of Thailand

in the South China Sea

near the jet's last known location.

But satellite data revealed the plane had flown

for hours after that last communication,

and was more likely somewhere over

the South Indian Ocean, the other side of Indonesia.

By the end of April 2014,

eight countries had joined the search.

After the initial scramble to find the plane failed,

Australia took the lead.

Based on where the plane was headed

and how much fuel it had,

they narrowed their search to a chunk of ocean

about 1200 miles east of Australia,

but narrowed down doesn't mean much in the ocean.

Now they were looking for a 200-foot-long plane

in a chunk of water the size of Pennsylvania,

if Pennsylvania were 13,000 feet deep,

totally dark and had never been mapped.

Australia hired Dutch oil and gas company Fugro

to run the 46,000-square mile search.

They used sonar to map the sea floor,

looking for hazards like underwater volcanoes.

By early 2015, new maps in hand,

Fugro was operating four deep-tow systems.

These are basically sensor pods

that get dragged along just 300 feet above the sea floor.

Fugro's also sent out an underwater drone

to go where the tow can't.

By this point, the team has scoured 33,000 square miles

of ocean floor, hasn't found any sign of MH370,

but the search hasn't been a total wash.

Check out this rad 19th-century shipwreck.

Australia says that by the middle of this year,

the full 46,000 square miles will have been covered,

and if nothing comes up, that's it.

It won't expand the search area again.

But there are already private groups

talking about picking up where Australia left off.