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Old 5th Jun 2006, 04:13
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TOGA Descent
 
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Originally Posted by Schmoogle
When using the Jeppesen flt planning system to calculate max payload, fuel required for given payload etc. Why does the system assume that the 5% contingency fuel is burnt by the time you arrive. The fact is that this fuel is a buffer of extra fuel in case the situation arises where you might need it, but if this situation doesnt arise, then you arrive at your destination with it still in the tanks. If you are arriving at max landing weight, the reality is that you are arriving at your max landiing weight, plus the weight of the contingency fuel. In other words an overweight landing, which could be several tons over your max ldg wt. This is concurred when the loadmaster completes his loadsheet, where the maths don't lie. His loadsheet in this case will show an overweight landing...

We use the Jeppesen Flight Planning system at my airline. I've read through most of this thread, and have to apologize if I offer some redundant information, as I got a little lost in all the postings.


The Maximum Landing weight calculated in the Jep System is the Take-off weight, minus the "Trip Fuel" and "Taxi Fuel". The "Route Reserve" (Contingency) is included, along with the Alternate and final reserve fuel in the landing weight computation, and is assumed to NOT be burned during flight.


In the Airbus there is a simple test to prove this. In the FMS (MCDU) INT-B page, set all the fuel parameters as indicated on the Jep Flt plan (Trip fuel and alternate are computed, but normally the same as the Jep System), and the others can be manually entered.


Then, read the landing weight with a 5% route reserve. Now, set the route reserve to 0% and read the landing weight. It will indicate No change to the original weight, but the "Extra Fuel" available will show an increase.


This was confirmed when I asked a dispatcher to run two flight plans for the same route, but with different Route Reserve (contingency) settings. 5% and 0%.


Not sure why you have different numbers on your load sheets though. Possibly your Jep Sys, and Load Planning System are not configured in a compatable manner.


Hope this simplifies the answer for you.

Cheers
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