The cabin crew had posted comments in a discussion on Facebook which Virgin Atlantic said brought the company into disrepute and insulted staff.
Though the group has disappeared from Facebook, newspapers have reported that the comments insulted customers, claimed that planes were full of cockroaches and called planes' safety into question.
"Following a thorough investigation, it was found that all 13 staff participated in a discussion on the networking site Facebook, which brought the company into disrepute and insulted some of our passengers," said a Virgin Atlantic statement. "It is impossible for these cabin crew members to uphold the high standards of customer service that Virgin Atlantic is renowned for if they hold these views."
Calling the behaviour "totally inappropriate", Virgin Atlantic said that the posting of the comments broke its staff policies.
Employment law expert Ben Doherty of Pinsent Masons, the law firm behind OUT-LAW.COM, said that the case illustrated how important it was for companies to make sure that they had up to date policies to deal with workers' online behaviour.
"Virgin Atlantic's actions show that companies can deal with the behaviour of employees on social networking or other sites, and that its much easier to do so if they have a policy in place that outlines what is expected of employees, but only if that policy is communicated to employees," said Doherty.
"The message for would-be posters is to be careful when commenting on your employer and make sure you know what its policies say," he said.
Workers at British Airways (BA) have also come under scrutiny in recent days over comments made on Facebook about customers.
BA ground staff at Gatwick Airport have reportedly insulted passengers, called them smelly, complained about them putting boarding cards in their mouths before handing them over and made comments critical of BA's opening of Terminal 5 at Heathrow.
A BA spokeswoman told OUT-LAW.COM that it would discuss the comments with the employees concerned.
"We will be talking to the individuals concerned about their disappointing and unwise comments which are totally unrepresentative of the vast number of hard working groundstaff we employ at Gatwick," she said.
Virgin Atlantic said that staff had other avenues available to them for grievances.
"There is a time and a place for Facebook. But there is no justification for it to be used as a sounding board for staff of any company to criticise the very passengers who ultimately pay their salaries," said its statement. "We have numerous internal channels for our staff to feed back legitimate and appropriate issues relating to the company."