Can things get worse for USAir? Today, the airline announced a $322 million loss for the fourth quarter of 1994, a year that saw twotragic USAir crashesand was marked by stubborn labor disputes. Company officials blamed much of the loss on a "dramatic dropoff" in ridership because of the crashes. At the same time, Robert Oaks, the retired Air Force general USAir hired as its safety chief in order to restore public confidence in the airline, rejected speculation that pilot error caused theSept. 8 USAir crashnear Pittsburgh that killed all 132 people aboard.