The U.S. aviation sector was struggling to return to normal on Wednesday after a nationwide ground stop imposed by the Federal Aviation Administration (FAA) over a computer issue that forced a 90-minute halt to all U.S. departing flights. More than 10,000 flights have been delayed so far and over 1,300 canceled, according to FlightAware, in the first national grounding of flights in about two decades. Many industry officials compared the grounding to what occurred after the terror attacks on Sept. 11, 2001.