Fuel Q

[broadband circuit]

MAND went up 500kg!

Let's play them at their own game. Every time the ZFW drops, then rather than use the correction, ask for a new plan.

They have a choice, either give me a new plan (time cost), or I take the CFP fuel based on the original weight (fuel cost). Let IOC decide which is their preferred option.

Unlike many things in fuel policy, Depress Fuel at the crit point is not just a planning requirement, and if you leave without it, or more to the point, arrive at the crit point without it, you are operating outside the requirements of the AOC.

OK, the chances of having a depress at or near to the crit point are slim, and the chances of having it happen on the day you've reduced fuel via the correction are even slimmer.

HOWEVER, if your flight file gets selected at random by the CAD in one of their audits, and they conclude that you were operating not in accordance with the AOC, who gets called into the office? (hint: it's not the dispatcher, or load controller or IOC)

Even worse, if you do it going eastward, there have been cases in the past where the authority at the destination (read NavCanada or FAA) has boarded the flight to do a document audit. Once again, who will be held responsible?

Not worth it, give me a new plan, or I take CFP.

[fire wall]

Trip fuel vs zfw is not a linear relationship
Mand fuel vs zfw is not a linear relationship.
ie if the zfw is down 2% then the burn is not down 2%....worse if the zfw is increased. Why ? Too long a discussion.
Within small variance in ZFW then the corrections are relatively accurate and I would suggest to a limit of approx 2T ULH and 5T on short haul flights.
Within those boundaries I do an adjustment and add a bit for inaccuracies so that I am on the "right" side of the error.
Outside that then get a new flight plan.

[Loopdeloop]

I think most pilots do something similar, although I know some folk like everything to be accurate to the kilo. Unfortunately, flying doesn't work that way. Personally I use the correction figure up to about 5T and add a fudge factor thereafter, always rounding in my favour.
Do we really need everything mandated? I would hope that most pilots can think for themselves using some common sense and airmanship... oops, did I use the A word?

[PatObrien]

Yooo hoo, Mr. Broadband

That Crit point and associated Mand fuel IS ONLY a planning requirement (hence the term 'flight plan'). ANO requires us to be able to reach a suitable airport if depressed (which I usually am on flights over 2 hrs) hold for 30 min and land anywhere along the route DURING THE ACTUAL FLIGHT. The airports used when Mand fuel is required during the planning stage are usually far and wide, maybe because of planning wx requirements, but really to keep the dummies from cutting it too close and running out of gas during contingencies (like all the other fuel planning rules). If you want to keep eyeballing PANC and Kansai Crit fuel as you cross the ocean, go ahead. But likely RJCC, UHPP, PASY and a few others are suitable during flight, and that Crit pt is a non factor - as is the Mand fuel figure, the 5% contingency, and that vertical descent profile we planned on in Despatch.

If there's someone in CAD that can sort through one of those abused flight plans and actually find someone who was below Enroute Diversion Fuel during flight, and you can prove this myth, I'll give you my next year's bonus.

[Liam Gallagher]

Like I said before, talk it through with some of the trainers. There's a lot more to this than meets the eye. The OP mentioned crit pts, which could be ETOP points, that can be dealt with by selecting another ERA. Mandatory Fuel, is a bit more complex as you probably don't have scope to select other ERAs. Do you need it once you dispatch anyway???

I agree with Firewall and have experienced the same with a large 0FW drop (5T). Had we used the corrections on the original CFP we would have dispatched with 500kgs less than the new CFP calculated. The corrections assume linear changes and over a small change-weight range are a useable approximation, however over a larger weight change and a long flight these assumptions get stretched.

Again, talk to to an adult, but when carrying Mandatory, I reckon our Fuel Required is calculated on the basis of depressurising at the most critical depress crit.pt, and then we fly at FL140 etc, which means we are so far off Optimum Level (particularly in the 747) for a long period of flight. Put all this together, and I am cautious when carrying Mandatory on ULH, the change between weight and burn is not linear and ratios become unreliable proportionate to weight change.

Don't get me wrong, the corrections are good 99.9%, however on ULH when carrying Mandatory, I am cautious. ETOPs, different game as you can probably pick other ERAs to launch, the use the FMC airborne to finese and monitor.

Clear as mud?

[China Flyer]

Pat: I don't really agree with you, but that's because where I fly, the planned ERAs are the only ERAs.

Therefore, I really need to have the planned fuel when I'm in the air, 'cos there are no other options available.

So I think that BC's statement here is absolutely correct:

Unlike many things in fuel policy, Depress Fuel at the crit point is not just a planning requirement, and if you leave without it, or more to the point, arrive at the crit point without it, you are operating outside the requirements of the AOC.

[fire wall]

Pat, whilst what you say is correct I side with China Flyer.
On NoPac and Polar routes in winter the ERA's are the only options I have and , on a particularly bad day they are RJCC-PACD and PACD-PANC. Petro is one way and normally vis ugly in +SN and Shemya has a wind that would strip flesh whilst claiming <1000ft in FZFG (yup, how in 50kts is beyond me) and to top it off vvv///.

If I am missing something then I am happy to be corrected .

[PatObrien]

China, give me an archived filght plan on the route you're referring to and I'll take a look. Even if the airborne ERAs are the same as the planned, you still have the 5%, and to a lesser amount the immediate descent to 14 or 10k, which may be TONNES different from what is actually required airborne.

Have you or anyone you know ever gone below this INFLIGHT requirement? If so, what was the resulting course of action?

I'm having trouble recalling a time on NOPAC when I was stuck with the same ERAs inflight. UHPP is an option 90% and PASY 30-40%.

[bellcrank88]

ERA's and Fuel Correction

On almost every single YVR flight you are limited in your choice of ERA's. There are no other options.

Somewhere in what used to be Vol 1 and is now Ops A it used to say that if the change in weight was more than 5T, then get a new flight plan. Can't seem to find it anymore although it may be hidden there somewhere.

[cxorcist]

Now that seems like a useful number. I can remember that...