The Switch: Here's how we know MH 370 kept flying for hours

As the search for Malaysia Airlines Flight 370 continues, attention is turning to the onboard technology that allowed the plane itself, rather than the pilots, to communicate with the ground. Even if an aircraft's transponder has been disabled, its most basic systems, such as the engines, can also send status information back to ground stations, including the engine manufacturer or the airline. Investigators have now determined that some of these systems were still active on Flight 370 hours aft...