772 and 773 FMC max alt margin

[Check Airman]

Assuming smooth air, how much margin do you like to give to the FMC maximum altitude on the 777?



I’ve seen some people say as high as 2000ft. I’ve been 900ft below max (can’t recall if it was a 200 or 300) and thought the buffer was sufficient.


At my company, everyone seems to have their own “feel good” number. It’d be great to find something written down that I can reference the next time it comes up.



Thanks