zvezda
Posts: 8891
Joined: Sat Aug 28, 2004 8:48 pm

### SYD-LHR - Westbound Or Eastbound?

The great circle distance SYD-LHR is 9188nm. Obviously, due to prevailing winds, it makes sense to fly LHR-SYD eastbound close to the great circle route. However, SYD-LHR is not so obvious. The eastbound distance SYD-ANC-LHR is 10274nm. Which would require more fuel? To travel 9188nm westbound against prevailing headwinds or to travel 10274nm eastbound aided by prevailing tailwinds?

kl911
Posts: 3981
Joined: Mon Jul 21, 2003 1:10 am

### RE: SYD-LHR - Westbound Or Eastbound?

hmm, a 1000nm extra is really a lot. Good question though, I've been wondering this often.

KL911

ssides
Posts: 3248
Joined: Fri Feb 09, 2001 12:57 am

### RE: SYD-LHR - Westbound Or Eastbound?

Well, the airlines that fly the route do it westbound. This probably has more to do with the fact that there are more pax on a SYD-SIN-LHR routing than a SYD-ANC-LHR routing.
"Lose" is not spelled with two o's!!!!

PADSpot
Posts: 1637
Joined: Sat Jan 15, 2005 11:31 pm

### RE: SYD-LHR - Westbound Or Eastbound?

Beside the pax issue, it's generally hard to estimate without the exact weather parameters and aircraft type. Fuel burn does roughly depend on air speed, but not to the speed over ground. Therefore you need to calculate the time you need and then multiply this with the average fuel burn per hour. And even this only gives you a rough impression:

If you do SYD-ANC-LHR (tail winds) with an average speed of 475kts / ~920km/h you roughly need 20:40h (plus the time on the ground, although you don't consume fuel there.

Lets assume you can do SYD-LHR (head winds) nonstop, which even the 772LR won't be able to do (unles the weather is extremely advantageous) and you reach an average speed of 430kts / ~800km/h you will need 21:16.

Thus SYD-ANC-LHR could be better, but the judgement could turn into the opposite in case the weather is different in a way that speeds are different. But certainly the SYD-LHR leg doesn't get better if have to do a fuel stop at lets say HKG as it certainly increases the total amount of fuel needed.

rgds,
Jan

Edit: The time needed is almost equal on both routes in case you only fly at an average speed of 465kts / ~900km/h on SYD-ANC-LHR. The pax issue is not enough reason either to choose the westbound route. Maybe offering a LHR-ANC flight gives you enough pax to fill the bus, LHR-HGK is served by many others.

[Edited 2005-05-23 16:32:42]

bearcuban12
Posts: 89
Joined: Wed Mar 30, 2005 11:22 pm

### RE: SYD-LHR - Westbound Or Eastbound?

I have flown LHR - MEL and return a number of times via either SIN, HKG or BKK. I have also flown LHR - MEL and return via LAX.
I can tell you that the total transit time for LHR - MEL via LAX is about 6 hours more than via SIN.

MKEdude
Posts: 957
Joined: Thu May 05, 2005 9:55 am

### RE: SYD-LHR - Westbound Or Eastbound?

Is it possible to go SYD-ANC without stopping? Perhaps a 777ER.

If not, what about SYD-HNL-LHR?
"You can't be a real country unless you have a beer and an airline." Frank Zappa

PADSpot
Posts: 1637
Joined: Sat Jan 15, 2005 11:31 pm

### RE: SYD-LHR - Westbound Or Eastbound?

 Quoting MKEdude (Reply 5):Is it possible to go SYD-ANC without stopping? Perhaps a 777ER. If not, what about SYD-HNL-LHR?

SYD-ANC is only something about 6400nm / 11800km. There are a couple of aircrafts that can do it. As we were also talking about SYD-LHR westbound I was anyway thinking about a fictive aircraft or a 772LR.

But flying SYD-HNL-LHR would certainly work too and don't alter my calculation.

[Edited 2005-05-23 18:26:48]

zvezda
Posts: 8891
Joined: Sat Aug 28, 2004 8:48 pm

### RE: SYD-LHR - Westbound Or Eastbound?

 Quoting Bearcuban12 (Reply 4):I can tell you that the total transit time for LHR - MEL via LAX is about 6 hours more than via SIN.

SYD-LAX-LHR is 974nm further than SYD-ANC-LHR.

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