Thanks BD. I know ZFW means Zero Fuel Weight but this scenario which I have mentioned is an abnormal situation where you have 7 tons fuel stuck in the main tanks due to pumps failure. So this 7 tons fuel which you routinely burn first is dead weight now. If the fuel weight starts to reduce from the main tanks (as flight continues) we will be heading towards the ZFW limit. Although we have fuel in the center tank but we cant use it and it will behave just like payload.
In non standard refueling i.e. Main tanks not full while there is fuel in the center tanks, the rule for planning is:
Actual ZFW + Fuel in Center Tank should NOT be greater than ZFW Limit
That means even if your center tank fuel gets stuck in flight you will still be safe from busting your ZFW limit, as it is already catered during flight planning.
My scenario is a case of standard refueling where Main tanks are topped up first and then the center tank.
Last edited by Haroon; 12th Dec 2009 at 04:19.