Rescue workers bow their heads during the mourning ceremony on June 7. [Photo by Cheng Min/Xinhua]

4. Why Eastern Star did not send out distress signal?

According to CCTV, it was from a call sent out by a ship near the site that the marine department learnt of the disaster. Then why didn't the Eastern Star send out distress signal itself?

According to Li Jiang, the deputy head of Yangtse River Marine Bureau, the ship was not equipped with Global Maritime Distress and Safety System (GMDSS), because the automatic alarm device is not mandatory for river boats in China. As a result, crew members have to call for help by themselves.

Besides, it took only around a minute for the ship to get caught in freak weather and capsize. Such a short period means it was difficult for a crew member to sniff the danger and send out alarm manually, according to a professor of Wuhan University of Technology.

5. Is there a black box on the ship?

The Eastern Star was not equipped with the Voyage Data Recorder, or the black box, because the device is not mandatory for river boats in China.