Most Marine and Air safety regulations are written in blood. Starting largely with the Titanic disaster, which resulted in the SOLAS convention
While its easy to write a regulation that prohibits. Thou shalt not.
Others are not so easy to write, because they must take into account the broad scope of different designs and applications.
They may have minimum standards for each application (minimum size of door of hatch) They will generally have the catch all phrase of "As Reasonably Practicable"
The sh1t show starts after an event when people (lawyers/ investigators et al) seek to define if the
Reasonably Practicable caveat was met
From an aerospace perspective:
When we find a failure during testing the solution is heavily subjected to risk/reward analysis which (simplified) are
Impact to cost, maintenance, operations & performance vs impact and likelihood of failure over total fleet flying hrs, passengers carried, and potential number of lifetime victims inc compensation monies. Which returns the reasonably practicable solution.
Unfortunately these are numbers on a page and far removed for the real impact on actual victims of the decisions made.
And yes every time an aircraft I've had design influence in goes down, I hope its not because of a choice or decision I made a number of years back.
