Most aircraft require increased pressure on the rudder pedals to achieve the same amount of rudder control at a higher speed. The Airbus A300 and later Airbus A310 models do not operate on a fly-by-wire flight control system, but instead use conventional mechanical flight controls. The NTSB asserted that the A300-600 rudder control system was vulnerable to unnecessarily excessive rudder inputs. The Allied Pilots Association, in its submission to the NTSB, argued that the unusual sensitivity of the rudder mechanism amounted to a design flaw that Airbus should have communicated to the airline. The main rationale for their position came from a 1997 report that referenced 10 incidents in which A300 tail fins had been stressed beyond their design limitation.