Fligth Safety - it's not impossible to modulate the rudder throws. It's not just zero or 100%. However, it is very very tough to modulate even after undergoing additional training that was implemented after the accident. Been there done that. However this was in training AFTER learning how sensitive the rudder was. Perhaps a key difference in being able to modulate the rudder travel was the lack of 'real time' pressure/time constraints.
Training included rudder displacements at <165 kts(?), 210, and 250 kts. The change from <165 to 210 kts was "hmmm, ok". The change from 210 kts to 250 kts was "whoa". It's just a different experience at the higher speeds. And the sim couldn't accurately duplicate the side loads being generated which might have changed it to "WHOA!".
I think the rudder travel is 1.3 inches above 250(?) kts. DC-9/S80 is 1.2(?) inches so it's not just the rudder movement that is the problem. It's rudder pedal travel, break out force, force after break out is achieved, degrees of rudder travel per pound of force, etc, etc.
google came up with this -
http://www.alliedpilots.org/Public/t...submission.pdf
Seems to me that the A320 incident shows the need for all airline pilots to have training in rudder use at high speeds to understand any limitations their particular a/c might have.