The computer allows you to cut down your design so that it will do "at least X and no more" so you can save a few cents and then the plane falls apart when the

The computer allows you to cut down your design so that it will do "at least X and no more" so you can save a few cents and then the plane falls apart when the pilot asks it to do Mach 3.6 but that's OK because the manual said it will top out at 3.5