Originally Posted by
Volume
Modern aircraft design has advanced with respect to weight saving, older aiframes typically have more strength margins than newer ones.
With all due respect, that's rubbish. Modern airframe designs tend to make greater use of lightweight materials and technology, but with advances in CAD and engineering tools load calculations can be simulated far more accurately than was once the case, meaning that the need for overengineering is reduced. Allowing for the fact that the evidence is anecdotal, you have two B777s (LHR and SFO), an A320 (Hudson River) and an A340 (YYZ) that all retained most or all of their passenger and crew compartment integrity when subjected to loads well outside the norm.
In contrast, overengineering gives a perception of greater structural strength, but it's an inexact science. No-one built airliners tougher on paper than us Brits (probably in response to the Comet 1 fiasco), but nevertheless the forces in a thunderstorm were capable of tearing a BAC 1-11 to pieces. Similarly, the B737 is very hardy in some aspects (I'm thinking Aloha's 737 "convertible"), but if you tap one too hard in the wrong place, the fuselage will fail roughly in the vicinity of the same two frames every time.