Originally Posted by
Winterking04
You have to send the Dispatcher any changes you are going to make (i.e. Mach, altitude, or route). Once they update on their end, the HOWGOZIT will be accurate.
That's probably true, but more to the point, it's all dynamic. We may be constantly changing various parameters during a flight. If it's not of any major consequence then you probably won't bother dispatch. If you added 2000 pounds of gas before your flight to make up for the inefficiencies of ATC, various other variables, then you are feeling confident that your fudge factor is within tolerance or at least your comfort level is on the good side.