Originally Posted by
safetypee
yoko1, similarly, how would you know if there was a gross error in one or the other value. Thus the need to know how each are calculated and which should have the greater integrity.
My point is that each of these sources are
calculated values and can only be as precise as the inputs into those calculations. I've had my share of misloaded aircraft over the years, so it is advisable to apply an appropriate amount of vigilance to the FMC value. With enough time in the aircraft, a pilot should eventually get a sense whether the FMC calculated value that they are attempting to fly is appropriate for the conditions. Fortunately, the 737's I operate have a direct reading of the AOA vanes displayed on the PFD which provides a good sanity check for one's approach speed. That being said, this aircraft is far more tolerant of being a few knots fast than a few knots slow.