I always keep belted in when seated
Which means they'll find you strapped to your seat when they sift throught the debris.
Unless, that is, you've been vapourised in the impact.
.....will work safely because most jets are now equipped with more advanced flight systems.
Which can still be outside prescribed limits, or even fail completely.
In addition, RVSM flight is, in theory and in law, not permitted if pre flight instrument checks are beyond prescribed tolerances.
This assumes that the Captain is willing to resist commercial pressures...........
aircraft not feeling comfortable in complying with RVSM procedures and deciding to follow routings that would avoid the reduced minimums?
"Not feeling comfortable" and thereby causing extra cost is not a lasting option in airlines such as the one I've worked for. A failed sim check with a management examiner and the sack would be the result.....allegedly.