Science has made us to believe that radiations or signals from phone affect airplane navigation systems. And with respect to that, Chinese authorities insist that all Phones should be switched off during flight.

What played out could be seen as being ignorant of the law, which doesn’t save you from the law. Between January 5 and February 6, three passengers have been arrested for using their phones on planes.

The first passenger and victim, a woman named Zhang allegedly refused to turn off her phone during take-off and actually made calls during a flight. She was held in jail for five days.
The second passenger named Niu was also detained for a cell phone offense but got only three days.
The last person who perhaps the most unfortunate, a woman named Wang allegedly listened to music during take-off and landing. Wang also got five days, the maximum for a cell phone offense. Fine charge up to 50,000 yuan (around $7,265) can also be imposed.

They take this rule serious inorder not to put the lives of other law abiding passengers at risk.
Info source;http://www.premiumstech.com/2017/02/Passengers-receive-five-days-jail-term-in-China-for-phone-use-on-plane.html?m=1

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