Days after a massive storm struck Atlanta, Delta Air Lines is still recovering from what airline insiders term an “irregular operation.” The carrier has canceled about 3,500 flights since Wednesday, more than the 2,300 canceled during the powerful computer failure in August that prompted CE Ed Bastian to apologise to passengers. Fuelling last week’s meltdown were Delta’s reliance on its Atlanta mega-hub and rules concerning how long flight crews can operate. While much was beyond Delta’s control -- including the surprisingly wicked storm that grounded all Atlanta flights for nearly 5 hours -- passengers, aviation experts and the airline’s own flight crews wonder if the carrier was slow to anticipate the storm’s severity and react quickly enough when communications started to break down. <br/>