The search is considered a key step in determining what caused the crash.
The cockpit voice recorder can record conversations, warning sounds, the background noise of the engines and even the movement of buttons on the control panel. The second device captures information about the plane’s speed, altitude and direction, as well as the pilot’s actions and the operation of all the aircraft’s key systems.
Investigators say it is too early to speculate on the cause of the crash. The plane began a dizzying and unexplained descent an hour after takeoff and stopped transmitting data 96 seconds after it began its descent.
The China Eastern flight was covering the route between Kunming, in Yunnan province, and Guangzhou, an industrial hub on China’s southeastern coast. The Shanghai-based airline is one of the four largest in the country.