Discretionary fuel decision making

[framer]

Thanks FullWings, I’ve never flown long haul but from what I hear the fuel planning is more consequential than the SH stuff I do.

[Amadis of Gaul]

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.

Yes, I have such a method.

[FullWings]

Originally Posted by framer

Thanks FullWings, I’ve never flown long haul but from what I hear the fuel planning is more consequential than the SH stuff I do.

Much of the time, minimum legal fuel at many destinations gives you plenty of options and you have the whole flight to monitor the situation and update the plan. There is also the fact that to arrive with a greater margin than originally planned on a long sector, you have to upload significantly more than that to account for the increased burn to carry it all the way there, which can be a lot on a 15hr sector.

On SH you might get CDG with ORY as the alternate but for some LH destinations the nearest div could be an hour or two away and not somewhere you’d really want to end up, so unless it’s hopeless at destination using the alt fuel and committing is normally the better option. Or an en-route tech stop.

[RandomPerson8008]

Where I work every flight plan provides 75 minutes of fuel remaining at the alternate (or destination if no alternate required), which is, in most cases, 45 minutes beyond the legal requirement. As such, requesting more fuel than flight planned will result in a call from the chief pilot.

[I-WEBA]

Originally Posted by framer

This is good advice. Know what your machine burns in ten minute blocks so that when you’re deciding on your final figure you can add ( for example ) ten minutes for the hold that you’re 80% sure you’ll get inbound due to the runway configuration for example. Also, when you shut down on the gate, point at the fuel gauges and think “am I happy with that amount?” as that will form part of your future decision making.
Question for the OP; do you have a figure in mind that you want to land with on a perfect day? For example, if the TAF is perfect, the traffic is light, there are no MEL’s etc….. what do you think is a sensible amount of fuel to plan to land with? For me this is the foundation of my planning decisions. Think about arriving on that perfect day and then getting a moderately complex non normal when on final approach, doing the missed approach, running the checklist, doing the second approach and landing…..what do you want to see on the gauges when you land? How much did you burn in the missed approach and running the checklist? Do you want to have 30 mins fuel left when doing the second approach? Everyone will be slightly different on this one but figure out what yours is and tell us if you’re brave enough to Again, good question.

Thank you everyone again for the great inputs. On a perfect day my idea is that I want to see in my tank the finres+ alternate fuel + contingency.
if I see this as a minimum it’s definitely perfect. Most of the times with a few shortcuts it’s definitely higher.
I see however on the line some people quite scared with low CNR. This is typical obviously with neo aircrafts where people tend to adjust in order not land with less than 2.0/2.5T….
All this is valid in normal scenarios, then obviously if landing on a short runway and on final have a “simple” failure like flap/slat lock in intermediate position that prevents me from landing in that runway, probably consideration that if the airport is maybe LMP or a greek island might be difficult to reach another longer runway with increased fuel consumption…..

[Propellerhead]

It's good that you're thinking about it. A lot don't and just take extra fuel for the sake of it. Technically with statistical contingency fuel a good day is landing with FR + Alt + at least some of your contingency fuel. If the above scenario did happen then that's what final reserve fuel is for - uncomfortable I know.

[PENKO]

To start with your last point, you are absolutely right, it's a scenario that does not get the attention it deserves: a stuck intermediate flap over a destination with a very short runway can lead to an interesting scenario where you have less fuel than ideal to divert to a longer runway. This is definitely something to keep in the back of your mind, but I don't think you can make hard and fast rules for this (very selective) scenario. Captain A might reason that contingency fuel and final reserve will cover the alternate fuel shortfall in this scenario, captain B would take some extra fuel for 'stuff like this', captain C is far more worried wether the giros grill is still open by the time you make it back, captain D takes 500kg extra regardless, even to Copenhagen. I don't think you will ever get a definitive answer to this question, the important thing I think is that you have considered it!

Now to the typical NEO CNR jitters: this is pure psychology! And I get it. Having flown CEO's for decades, suddenly this hyper efficient NEO flight plan shows up with a CNR which would have instantly caused a fuel mayday call in the past. It takes time to adjust your comfort zone

Personally, flying short haul over Europe, arriving with CNR in the tanks (or slightly below) does not bother me on a normal day, there are plenty of options. If things don't go according to plan, like Morgan wrote before, follow the procedure, call minimum fuel or mayday as needed and make a safe landing.

[45989]

I always took what was appropiate. Simple decision really. Never questioned about fuel. Common sense should apply, I get the feeling now that 'managers' are deciding fuel policy in many airlines especiallly the low cost ones.

[FullWings]

At the end of the day, no matter how much or little fuel you took, it’s the plans you’ve made and the actions you take when it’s running low that are more important. Have a plan A but also a plan B, C, D, E & F.