Sources: Flight 370 altitude likely dipped to 5,000 feet

Sources tell CNN it appears that Malaysia Airlines Flight 370 disappeared from military radar for about 120 nautical miles.

According to a senior official with the Malaysian government, the absence from radar means it likely dipped below an altitude of 5,000 feet.

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What would have caused the drop in altitude? And how dramatic of a drop would it be for the plane to make?

CNN's Martin Savidge is in the flight simulator to demonstrate how an altitude drop would play out.