Originally Posted by vilas
Dutch roll on B707 has no similarity in Airbus. 707 was notorious for that and whatever little time I had on 707 I experienced it on a commercial flight, yaw damper failure kept causing vicious yaw and turn till I think the weight and altitude reduced to a certain level. I was trained for yaw damper failure in A310 simulator and it was nothing as compared to 707. Airbuses are not prone to this. So KC 135 comparison is futile.
Dutch roll is a normal oscillation regulated by yaw damper. Divergent dutch roll is another thing, one way among others toward PIO/APC on three axis, who have a great variety of causes and dynamic, often aggravated by unadapted pilot's response.
Learning from any of these accidents or incidents is never futile !
Switching the yaw damper to ON if OFF, or OFF if ON is far to be enough following a correct rapid diagnostic.
Pilots are mostly untrained to reduce or stop oscillations in their actual and always surprising form. A whole culture to understand unsteady dynamic is missing to pilots. Engineers building Y/D and Stability Augmentation systems who have that closed loop culture don't imagine all the cases of oscillations -rarely pure sinusoids- involving pilots by actions or only effects in flight in real and short time.
That must be improved and cooperation and communication between pilots and aeronautic and systems engineers enhanced and not limited to test flights. The solution is not replacing true test pilots and test flight engineers by airline pilots. Oscillations need to be studied by pilots in many forms.
Military are concerned as well as civilian pilots, both have their flight envelope limit where understanding a little more in the marge may switch life to death.
Of course it has a cost, not decreased by ultra-modern FBW or aging planes. But accidents have greater cost.