Just another piece of information that might be helpful and lends credence to my former supposition that indeed max service alts are somewhat artificial.
(Interestingly, in the 737 series I fly, max service alt is FL370 but one may select up to FL420 on the pressurization panel. Seems to me then, from a systems point of view, the restriction limiting the airframe to this level is then either aerodynamic or somewhat artificial. My own experience suggests that certainly at light weights, the aircraft would be quite capable of climbing higher.)
I know that, certainly, on the Smiths FMC, there are relevant PERFORMANCE FACTORS (to the incident in question) which may be selected via the Maintenance Pages.
They are the Min ROC parameters in CLB, CRZ and ENG OUT and the MNVR MARGIN.
These are Management selectable options.
The ranges are:
MNVR MARGIN: 1.15 - 1.60
MIN ROC: 0-999 ft/min
Knowing what the company set these values at might reflect how
they perceive the limit.
These values obviously don't change the certified service limit but they do govern how close one may approach the edge of the flight envelope in the various phases of flight.
And IMHO, if the FMC predicted MAX ALT at 58T with a CG location of 15% MAC is 368, it seems quite clear to me that at 50T, the aircraft is capable of going higher than 370 all other things being equal.
Won't help you out of a jam I suppose, but I believe it demonstrates the
articial nature of the limitation in question.
That a breach of this limitation should even be considered akin to a breach where a TCAS RA was ignored is lamentable.
