It looks like whoever was piloting the missing Malaysian airliner was trying to mislead controllers on the ground. 

Malaysian officials say the last words from the cockpit were spoken after the plane's main data communication system was turned off.  There was no indication of any trouble on board the aircraft when someone told air traffic controllers, "All right, good night," as the plane left Malaysian airspace. 

Officials say it's not clear who was speaking. 

It's already been established that someone on board Malaysia Airlines Flight 370 purposely turned off the plane's data communication system and its transponder 14 minutes apart.