Bottom line
Several days ago, a woman managed to board a Delta Boeing 767 from New York to Paris without a ticket. The crew eventually became suspicious, when they noticed her repeatedly moving between lavatories.
The Russian national with a US Green Card requested asylum upon landing in Paris, and it wasn’t her first time making such a request. She was ultimately denied, and a few days later, was put on a Delta flight back to the United States.
Unfortunately that wasn’t so straightforward, since she had an outburst on the return flight, and refused to cooperate with the crew. As a result, she was removed from the flight, and remains in French custody.