Chautauqua Airlines for the first time will operate commuter flights for American Airlines out of Chicago O'Hare. American plans a 13% increase in O'Hare flights this summer, but almost all of that growth will come in commuter aircraft rather than larger jets. American Eagle pilots say the outsourcing deal is a violation of their contract, but American disagrees. As the airline shifts capacity away from the old TWA hub in St. Louis, Chicago is set to eclipse Dallas-Fort Worth as American's largest base for regional jets. "There are a lot of communities surrounding Chicago that are small and midsized," says a company spokeswoman. "It is more cost-effective to serve those communities with smaller aircraft."