Locating Flight 370

The other day they announced that the mysterious Malaysian Airlines flight 370 had definitely flown all the way to the Indian Ocean and then crashed. How did they figure that out? 

It's really kind of ingenious. What they did was use the plane's satellite 'pings', the Doppler Effect, and information from other jets that flew that route.

The Doppler Effect, one of those things you probably heard about while sleeping through science in High School (so it must be in your subconscious someplace!), is the very technical scientific principle that train horns and police sirens sound higher when they are coming toward you than they do when they're going away. 

As it happens, that works on radio signals too, and the one form of communication that was still operating on MH370 was it's satellite 'pinger' (where the satellite repeatedly says, "Need anything?" and the plane usually responds, "Nope.")

Mr. Doppler's effect

So basically what some British scientists did was use the pings to determine the plane's distance and direction (east) from the satellite -- and how long it existed before crashing. The Doppler Effect told them if the plane was moving towards or away from the satellite (away) and at what rate of speed. Then they compared that with past plane flights that gave off similar pings. They also knew how much fuel flight 370 had, which gave them the outer limits it could possibly reach.

This aviation blog reports there was one last incomplete ping received from the plane at about the time it would have been running out of fuel. That may have been transmitted at the moment of impact.

Now they just have to find it in a very deep, very inaccessible stretch of ocean.