CBS News (Feb. 21) -- The Transportation Security Administration is investigating a breach at one of the nation’s busiest airports. Eleven people passed through a security checkpoint that wasn’t fully supervised at New York’s John F. Kennedy International Airport early Monday morning. The passengers were able to make it all the way onto their planes without further screening. “The most vulnerable time for any kind of check point is in a transition period,” aviation security expert Sheldon Jacobson said. Jacobson, a professor of computer science at Illinois, said airport security is weakest early in the morning and during shift changes.