Sylvia Else wrote:
There have been incidents where airliners have been stressed well
beyound their design limits to recover from extreme upsets, and the
passengers and crew have survived to fly another day,

"design limits" is the real keyword here. And it applies to bridges as well as buildings.

The empire state building was built with tons of extra strength into it
because at the time, the knowledge of structural aspects of materials was not
very good. So you end up with a big fat heavy building that is very strong.
More recent buildings are built with much better knowledge of materials and
thus are built with more exact strength, much lighter materials and much
thinner structure.

Similarly, modern aircraft are built with much better knowledge of material
properties as well as aerodynamics. So the difference between the stated
limits and the actual physical limits are far less than planes built in the
1960s. So breaking the "limits" today may in fact be far more dangerous than
breaking the much less well known limits of the 1960s.



The A300 crash is a perfect example of why FBW is a good thing. had there been
FBW on that system, the pilot could have commanded the rudder to the max, and
the computer would have ensured that it only moved as far as was safe,
allowing pilot to concentrate on flying the aircraft instead of guessing what
the limits would be in that flight regime.

From what I have been told, the 320 330 and 340s do not have computer
authority on the rudder, one reason being that the rudder is so rarely used in
flight. (AA being the odd airline out).

However, I suspect that the 380 and 350 will have computer authority on the rudder.