[MFAFF]

All of these long fuselaged planes have similar characteristics...

The 747 isn't really a long fuselaged plane....the width to length ratio is 'good' in terms of it providing a decent 'stiffness' or resistance to longitudinal bending.

So the A330/340, the DC-10-6x (even the first extended 707s) all have relatively bendy fuselages. Now some flexing is inherently beneficial (all of the wings flex of a reason) in structural terms but in terms of pax comfort and 'impression' its a different matter.

The A330/340 structures, being newer and 'optimised' to a greater extent than the DC-8 have a greater flex...as the design can be simulated and modelled prior to manufacture to maximise the fatigue relief benefits with the minimum weights etc. I'm not certain the greater use of composites is related, they tend to be 'stiffer' as opposed to metals...but it might be simply a relative displacement of flex...ie certain areas are stiffer so the more flexible areas move 'more'.

Its been a long time since I flew behind the wing as it were....recent flights on a 777 and A380 were very interesting...the 777 has a 'stiffer' ride.. much more high frequency, low amplitude disturbances.. like in a 911, which when on an overnight flight makes for poor pax comfort (relatively).. whereas the 380 (double decker remember; on the upper deck) was much smoother and the ride much more comfortable... like a 928.

Mind you looking back to the wing the 380 wing was flexing far more than the 777 wings.. perhaps therein lies the answer. From memory the 747 wing was also far more rigid...

I think the long fuselaged a/c (especially those with a long moment arm behind the wing.. the distance from wing to rear stabs) are more likely to be prone to Dutch roll...hence the ventral fin on early 707s unless the vertical stab is 'over sized'...not saying this is an issue but it may be the a/c, espescially the active Airbuses may be working harder to counteract this...hence a bit of tail wagging.

It is interesting to see how the perception of A vs B is so pronounced...with B being viewed as 'safer' yet the accidents stats and reasons tends to suggest 'equality' in terms of a/c issues/piloting/WX and others....

The investiagtion into the AF flight will provide interesting reasons for airframe failure... because regardless of the reason it did fail. On a side note however a 767 was also suffered loss of reliable airspeed data in severe turbulence. The needed to reduce height and even with this did not regain reliable airspeed data.
This tends to support a pitot issue rather than inherent FBW concept issue...

Hohum...we shall see...