iwok From Sweden, joined Jan 2005, 1106 posts, RR: 0 Reply 2, posted (4 months 1 week 1 day 2 hours ago) and read 2506 times:
Quoting sunrisevalley (Reply 1):
From a flight plan , 16hr flight at about MTOW ; Burn at cruise for the first hour was ~8t and for the last hour ~5.6t.
DFWHeavy From United States of America, joined Jul 2011, 464 posts, RR: 0 Reply 6, posted (4 months 1 week 1 day ago) and read 2474 times:
Is landing with ~40,000 lbs of fuel the norm on a 777? Seems like quite a bit, but perhaps not not so with holding and diversion fuel. This particular circumstancehas about 3 hours of fly time remaining based on landing fuel.
sunrisevalley From Canada, joined Jul 2004, 3946 posts, RR: 4 Reply 7, posted (4 months 1 week 23 hours ago) and read 2432 times:
Quoting DFWHeavy (Reply 6): Is landing with ~40,000 lbs of fuel the norm on a 777?
I am not sure what typical mission rules are . In this instance the 5% contingency (48min./5504kg) is a function of the distance flown. Then there is the fuel to reach the alternate which in this case was CHC ( 58min/ 9729kg) and hold plus final reserve (45min/ 5494 kg). I am sure that there are persons on this list qualified to comment.
mandala499 From Indonesia, joined Aug 2001, 6172 posts, RR: 74 Reply 10, posted (4 months 5 days 18 hours ago) and read 2050 times:
If you want it cheaper in fuel, you can dispatch to Fiji, with AKL as 1st alternate, and CHC as your last alternate, and carry fuel enough to divert from Fiji to CHC.... that way you can save on the 5% contingency (You carry 5% to Fiji not AKL). Cheaper and still legal, and... still safe. Although, this is an oversimplified way of explaining it.
Mandala499
When losing situational awareness, pray Cumulus Granitus isn't nearby !
sunrisevalley From Canada, joined Jul 2004, 3946 posts, RR: 4 Reply 11, posted (3 months 4 weeks 1 day 7 hours ago) and read 1676 times:
Quoting mandala499 (Reply 10): If you want it cheaper in fuel, you can dispatch to Fiji, with AKL as 1st alternate, and CHC as your last alternate, and carry fuel enough to divert from Fiji to CHC.... that way you can save on the 5% contingency (You carry 5% to Fiji not AKL). Cheaper and still legal, and... still safe. Although, this is an oversimplified way of explaining it.
Mandala499
Looking at the flight plan , if I am reading it right, it would have saved about 1t in contingency fuel.
WingedMigrator From United States of America, joined Oct 2005, 2024 posts, RR: 57 Reply 12, posted (3 months 4 weeks 19 hours ago) and read 1550 times:
mandala499 From Indonesia, joined Aug 2001, 6172 posts, RR: 74 Reply 15, posted (3 months 4 weeks 3 hours ago) and read 1442 times:
Yes, I just did a quick calculation using ORD-PPG-AKL-CHC as the routing with PPG as dispatch destination and CHC as the final alternate, yes, saves about 1 ton of contingency fuel... Do that route daily, and you'd be saving 2 tonnes a day which gives it 730 tons a year. That's in contingency fuel savings alone.
Assume that means you land with 1 ton less fuel, how much fuel do you save for the whole trip by not carrying that one ton of contingency fuel? About 230kgs... that translates to 170 tons a year.
So now you save 1000 tons. Where I am, that means over 1 million dollars a year saved.
Is safety compromised? Well, you're still able to go to Christchurch and still have over 2h13mins worth of holding and save 1 million dollars a year... otherwise, you don't save the 1 million dollars and land with 2h22 mins worth of holding.
Unfortunately, there isn't much "eeking out every cent" in terms of dispatch creativity on ORD-AKL, but AKL-ORD am sure there are ways to save more... eg: dispatch as AKL-XXX-ORD, with YYY as a final alternate, but find XXX that would give the fuel remaining at ORD the equivalent of diverting from ORD to YYY and still have a 45min holding.
There's another method of using the destination as a final alternate + X mins holding, eg: AKL-XXX with ORD as destination, and upon getting near XXX, the aircraft would check if the conditions at ORD is good enough to go there with only enough fuel to go to another airport near ORD, but have certain requirements such as it can only be done if conditions at ORD is better than a certain minimum weather requirement, and have at least a second parallel runway to the expected runway. I think QF does this method but I cannot remember the rules clearly for this.
When losing situational awareness, pray Cumulus Granitus isn't nearby !
sunrisevalley From Canada, joined Jul 2004, 3946 posts, RR: 4 Reply 16, posted (3 months 3 weeks 6 days 11 hours ago) and read 1345 times:
Quoting mandala499 (Reply 15): Yes, I just did a quick calculation using ORD-PPG-AKL-CHC as the routing with PPG as dispatch destination and CHC as the final alternate, yes, saves about 1 ton of contingency fuel... Do that route daily, and you'd be saving 2 tonnes a day which gives it 730 tons a year. That's in contingency fuel savings alone.
Very interesting ! Are these some of the tricks of being a despatcher to eek out savings but still comply with the rules ?
mandala499 From Indonesia, joined Aug 2001, 6172 posts, RR: 74 Reply 17, posted (3 months 3 weeks 6 days 6 hours ago) and read 1293 times:
Quoting sunrisevalley (Reply 16): Are these some of the tricks of being a despatcher to eek out savings but still comply with the rules ?
Yes, subject to regulatory approvals though. If your regulators approve it, do it, if not... tough luck. The reason why this is possible these days is because of the accuracy in flight planning, predicted winds and temperatures.
Quoting iwok (Thread starter): I am wonder how fuel burn changes for a 777-LR as it consumes fuel over the course of a long flight.
Just to give an idea... Holding is much slower than the cruise speeds... but... at 35,000ft... at 320tons gross weight holding would give you 9950kgs/hour, at 260 tons it's 7250kgs/hour at 200tons it's 5350kgs/hour...
Mandala499
When losing situational awareness, pray Cumulus Granitus isn't nearby !
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