Flight 370's Transponder

It wasn't long after missing Malaysia Flight 370 took-off from Kuala Lumpur that the communications system became disabled, the plane's transponder was turned off, Malaysian Prime Minister Najib Razak explained Saturday.

The transponder is a tracking device, radio transmitter in the cock-pit that works with ground radar. It allows radar pinging to help air traffic controllers, on the ground, see what direction a plane is going and it's speed.

"All right, good night."

They were the final words heard from Flight 370's Transponder.

Questions are being asked about those final words.

Who spoke them? The captain? Co-pilot? What were the circumstances surrounding the words? Could someone had forced either the captain or co-pilot to say them? Possibly, there were others in the cock-pit that should not have been there?

Washington officials suspect it was one of the pilots, and one or both have involvement in Flight 370's plight, disappearance.

Someone, for unknown reasons, changed the flight's course by the time of the last spoken words.

Investigators searched the homes of the pilot and co-pilot, because they're looking into all possibilies for a clue of what could have happened to the plane. Why it happened?

The pilot had a flight stimulator that was taken by investigators along with other items.

A few more counties joined in the search for Flight 370, up from 14 countries.