zero fuel weight lies
A little food for thought for any fellow flight crews who, maybe foolishly, dispatch with actual plog fuel on a regular basis.
In Europe, (unfortunately Im not in a position to coment on the situation in the USA) under JAR ops....your ZFW as calculated by the flight planning system is based on average weights....it has been my experience that these weight are in fact "VERY AVERAGE". To explain further...your pax weights are average 85/75 kgs for m/f and baggage weights 13 kgs for european dests with 10k cabin baggage. Now, how many people do you know, go to sunny spain from the UK for thier 2 weeks of bliss, would have 13 kgs of luggage?? do you really expect all cabin baggage to weigh 10kgs, or, lets face it, are all the pax less than or equal to "average" weights.
So, take your 150 pax with say max permitted luggage of 26kgs ( why we use one figure for flight planning/fuel purposes and an entirely different figure ie double that, before we charge an excess charge requires consideration also).......and they WILL have max bag weight for a trip..thats an extra 2 tonnes for cash thats not accounted for in your performance calculations...and thats presuming that all the punters are coming straight from the local health farm, having shed lots of pounds, in order to board at that beautiful "average" weight.
Im making the point, purely from the point of view of safety...so taking the extra 500kgs of fuel, for "mum" makes a lot more sense than you may think. Also, round up those performance figure for either the flex temp.....take next lower, or T/O weight...drop down to the next line to ensure theres adequate performance for the intended op.
Please dont start a slagging match around this post,as it is, in my humble opinion good airmanship and a safer approach to flight planning.
and....may you always have 2 tonnes in the wings on landing
VHF1