MH370: How do 'pings' work?

At 8.11am on Saturday March 8, the Malaysian Airlines (MAS) MH370 flight sent out its last ‘ping’, or an electronic communication called a “Handshake” to the satellite.

This indicated that the aircraft was still in the air.

However, the "handshake" does not provide any additional data of the flight’s altitude, location and speed.

Two weeks without any credible information, Inmarsat a British satellite telecommunication company which owns the satellite 3F-1, collaborated with other analysts in narrowing down the search area in the southern corridor.

The 3-F1 Inmarsat satellite is one of the oldest satellite models used in the aviation industry.

It is a geo-stationary satellite as its orbit is at the same location.

It orbits the earth once a day and moves up and down the equator.

Before Inmarsat can pinpoint the location of MH370, it must first take into account the location of the satellite while it rotates around the earth.

Inmarsat's relies on three estimations: the speed of the plane, the satellite location and the ‘Doppler’ effect that detects the 'Pings'.

Using the 3-F1 satellite, Inmarsat detects the plane’s 'ping' and can trace the path that MH370 took.

That however did not work, so Inmarsat changed their operation strategy and began using the 'Doppler' effect.

The 'Doppler' effect can be explained simply by using an ambulance siren as an example. The sound of the siren becomes louder when it gets closer. This is the Doppler effect, that is the use of frequency sound waves.

Using the frequent 'ping' the plane sends to the satellite, and using the analysis of the speed of the plane, MH370 location can be traced accurately.

The question is, how far did MH370 fly after its last 'ping' at 8.11am?

Between 8.11am and 9.11am, investigators believe MH370 crashed in the Indian Ocean, assuming that MH370 flew at a relative speed and direction.

While the search for MH370 remains in the Southern Indian Ocean, it still covers a broad area which takes a lot of time and energy.