“Social media, and the internet more broadly, have changed the way we live and the way we keep in touch with friends and family, but it’s hard to find evidence that the internet has made us richer or more productive at work,” said Jay Corrigan, a professor at Kenyon College in the US.We know people must derive tremendous value from Facebook or they wouldn’t spend millions of hours on the site every day. The challenge is how to put a dollar value on a service people don’t pay for,” Corrigan said

“As part of our standard practice following any accident or incident, we examine our aircraft design and operation, and when appropriate, issue bulletins and make recommendations to operators to further enhance safety,” a Boeing spokeswoman said.