Originally Posted by
I-WEBA
Hello everyone,
I’d like to ask your opinion if you have a structured method (or just which process) you normally use to decide discretionary fuel. As FO I try to pick up captains method and most of them even asked this question just don’t have one. Tbh I see quite commonly “let’s take 500 extra” which is valid from every kind of situation.
i know some airlines used acronyms or I’d just would love to see your flow in order to take this decision.
Many valuable inputs already exposed in this thread. If I may emphasize, always consider the discretionary fuel you decide to take as extra time in the air for a specific purpose. This list can be pretty much endless depending on the threats of the specific day out. Generally speaking the "big families" which will lead you to take discretionary fuel are: Wx (some Extra could already be included in min block.), Notams (expected delays for many different reasons, from runway closures to VIP movements, etc..), MEL (must be included in the OFP as Additional Fuel), Local aerodrome knowledge (i.e. non radar-environment where you get to hold over the IAF till the preceeding traffic is somewhere on short final and so on). Tons of variables.
Try to come up with something that makes sense. For example, Enroute CAT forecasted? Might consider 1-2 FL downs fuel to increase the coffin margin. Destination Wx with gusty winds and/or showery/stormy phenomena at a big messy intercontinental airport? Consider anywhere between 30 to 60 min additional for instance, depending on how dodgy the SigWx/TAF look. Also if the destination looks frisky, make sure your alternate looks peasy. In case change the alternate or have the dispatcher change it for you. These are just a few points, but every single day on the line you will find threats which could well be mitigated
also (not exclusively) by carrying additional fuel.
The worst thing you can do as a professional is just throwing a number out, like "let's take 500 extra" or "1000 extra" just for the sake of it without knowing what those KGs are potentially going to be used for. For example if you want time to hold at destination because of TS forecasts, then local climatic knowledge will also be useful, i.e. average length of TS, where do they form mostly, etc.. generally speaking plenty of this information is covered in OM-C.
Bottom line try to learn day by day and fine tune your skills over time.