No security "in the world" could protect an airline from the kind of action taken by a co-pilot who French authorities say appears to have deliberately crashed a Germanwings plane, the head of its parent company said Thursday.
"Whatever safety provisions you have in a company, however high the standards, such an isolated case cannot be completely ruled out," Lufthansa chief executive Carsten Spohr told reporters.
"No system in the world can rule it out."