Thank you, to henra and BOAC in re attitude reference systems. Not familiar enough with what is used in big metal to have any intuitive feel for how they respond during upset. Your point on "no system fault" transmitted may have been the answer to my question in the first place.
Also a big thank you to PJ2 for the analogy in re data sampling, although I did cringe at the memory of strobe lights and the disco era. (At least you didn't meantion leisure suits and polyester shirts!
)
For syseng68:
Although messages may not be written in real time, or perhaps even in strict sequence of arrival is irrelevant, since each message will have it's own timestamp.
Good point.