View Full Version : fuel consumption

16th Sep 2007, 23:58
I was wondering how many kgs of fuel would be used by a 747 going from LHR to Seattle and whether it could set off with the usual contingency fuel or whether they would use the reclearance technique to make the numbers work?

17th Sep 2007, 00:23
G'day chrisbl,

That sector is about 9 hours flight time and well within the capability of a B747. Average fuel burn for a B747 is around 12 tonnes per hour, so that'd be around 110 tonnes burn plus whatever reserves you need. The total fuel capacity of a B747, depending on model is in the order of 160 tonnes.


17th Sep 2007, 02:06

I think if you put the gear up it helps!

You will find the fuel burn comes out closer to 10.5 tonnes/hour over a flight of that length, so about a 90 tonne fuel burn plus reserves, contingency and div to SEA - say 105 tonnes in tanks (vs 173 tonnes capacity)

Add to that a ZFW of 240 tonnes and you derive a TOW of 345 tonnes vs a max of 397 tonnes.

As Rainboe says, just a medium length flight - a stroll in the park for the QOTS:ok:

ray cosmic
17th Sep 2007, 02:24
You start getting in the arena of reclearance FPL for flights around 11:30 and high weights. Also depends if you talk Freighters vs. Pax.

18th Sep 2007, 07:58
If it is fuel burn then this is roughly how I see the figures.


But you ask about contingency. That is pretty much laid down by your airline and the regulatory authorities. If it is fuel in the tanks you mean, you won't arrive with much less than ten tonnes but my recall is less than perfect.

Funny about the old QOTS, you rarely see a question about her these days. Almost as if she did not exist. And as for KSEA (and even CYVR), two of my favourite haunts. Fine old runs, both of 'em and what fun the -200 was. A doddle.

But that's thread drift if ever there was an example. Pat the pig for me and spend an hour or two in and around Pioneer Square. Watch the lusty floatplanes up at Kenmore Air on the Lake, nobody is looking so enjoy a beer in Hooter's and tut tut about it afterwards. Tell me if the model railway is still in the bar opposite the Green Tortoise. And if you go to CYVR up the road, it's the steam clock, Gastown and the blue trail up Grouse Grind for you. And a swing on the suspension bridge half way back to the ferry. Tee Hee.

What a privilege and what memories to have been a QOTS driver.

My graph is for factory fresh by the way.

18th Sep 2007, 08:37
From a 'recent' LHR-YVR flight on a 747-400 Roller engined flight...

Payload 38 tonnes
TOW 328 tonnes
Flight Time 8:58
Fuel Required 102.5 tonnes
Fuel Burn 89.6 tonnes

So, moderate weight, medium length flight = 70 tonnes below Max TOW and 10 tonnes per hour fuel burn.

Long live the QOTS:ok:

19th Sep 2007, 15:41
Thanks everybody, very helpful and enjoyable to read.:D

19th Sep 2007, 18:25
its worth noting that excellent answers given to you by the UK based pilots consider contingency fuel to be in the region of 3-5%. As a FAR121 operator we use 10%, so we use re-clearance on flights of 5-6 hours or greater.

IATA are suggesting that airlines use re-clearance on as many flights as possible for fuel conservation.


19th Sep 2007, 22:04
The reclearance game seems to against the spirit of the contingency fuel rules.

Why dont they just change the rules to reflect that on long flights with large fuel loads the real contingency for the flight is not necessary. If widespread use of reclearance was in operation surely that just makes a farce of the reason for having it.