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Why SQ’s Southerly Route On EWR-SIN Non-stop?  
User currently offlineCoal From United States of America, joined Aug 2006, 2129 posts, RR: 10
Posted (6 years 11 months 3 weeks 22 hours ago) and read 8639 times:

Hi

I just came back from flying SIN-EWR and return on the A345 non-stop flight and was surprised to find that both legs, especially the return, were flown at a very southerly route.

On the SIN-EWR sector we flew a route that roughly went Singapore-Taiwan-Japan-Kamchatka-Alaska-Yukon-Michigan-Pennsylvania-New York. But on the return we took a route that seemed even more southerly than that taken by transatlantic flights from the US to Europe. Our routing was roughly New York-Bangor-Le Havre (didn’t even come close to Ireland)-Paris-Geneva-Belgrade-Sofia-Istanbul-Teheran-Mumbai-Malacca-Singapore.

Would favorable winds be the only reason for this? It seems logical that such a flight would initially head north to the pole and then south towards Singapore.

Cheers
Coal


Nxt Flts: SQ SYD-SIN-DEL-SIN-SYD | VA SYD-DPS-SYD
39 replies: All unread, showing first 25:
 
User currently offlineMpdpilot From United States of America, joined Jul 2006, 1005 posts, RR: 0
Reply 1, posted (6 years 11 months 3 weeks 22 hours ago) and read 8541 times:



Quoting Coal (Thread starter):
Would favorable winds be the only reason for this? It seems logical that such a flight would initially head north to the pole and then south towards Singapore

I know airlines use computers to find the most favorable winds possible for the trip and with the strong winds out of the west would make an easterly flight path mor favorble than the northerly one you suggested. This is just my guess there may be other reasons.



One mile of highway gets you one mile, one mile of runway gets you anywhere.
User currently offlineIkramerica From United States of America, joined May 2005, 21582 posts, RR: 59
Reply 2, posted (6 years 11 months 3 weeks 21 hours ago) and read 8512 times:

Probably winds combined with not wanting to route over the poles if diversion airports are too cold for comfort. It's the peak of northern winter, where the jetstream is very strong and the arctic very cold, so riding the winds while avoiding the poles is a good plan if possible.


Of all the things to worry about... the Wookie has no pants.
User currently offlineCoal From United States of America, joined Aug 2006, 2129 posts, RR: 10
Reply 3, posted (6 years 11 months 3 weeks 21 hours ago) and read 8416 times:

OK, that makes sense. However, this puts things a bit into perspective:

SIN-EWR across the pole:


SIN-EWR the way we flew:


Cheers
Coal



Nxt Flts: SQ SYD-SIN-DEL-SIN-SYD | VA SYD-DPS-SYD
User currently offlineBoysteve From United Kingdom, joined Apr 2004, 956 posts, RR: 0
Reply 4, posted (6 years 11 months 3 weeks 21 hours ago) and read 8409 times:



Quoting Coal (Reply 3):
OK, that makes sense. However, this puts things a bit into perspective:

SIN-EWR across the pole

Was you flight on time? Or the flight duration as expected?


User currently offlineIkramerica From United States of America, joined May 2005, 21582 posts, RR: 59
Reply 5, posted (6 years 11 months 3 weeks 20 hours ago) and read 8371 times:



Quoting Coal (Reply 3):
OK, that makes sense. However, this puts things a bit into perspective:

Not important. The shortest path between two points isn't always the best. If the path you flew took advantage of very high tail winds (100 knots) then the 8 hours it was in this path would make up for the 800 extra nm flown.

Add to that that going up over the pole may even have meant going against the wind for an amount of time, meant plotting for dangerous diversions in the peak of winter, and paying russian overflight fees, it was likely better to fly the way SQ flew it. They avoided flying over Russia in both directions if nothing else...



Of all the things to worry about... the Wookie has no pants.
User currently offlineViscount724 From Switzerland, joined Oct 2006, 25999 posts, RR: 22
Reply 6, posted (6 years 11 months 3 weeks 20 hours ago) and read 8349 times:

Quoting Mpdpilot (Reply 1):
I know airlines use computers to find the most favorable winds possible



Quoting Ikramerica (Reply 2):
Probably winds combined with not wanting to route over the poles if diversion airports are too cold for comfort. It's the peak of northern winter, where the jetstream is very strong and the arctic very cold

I wonder if flight planning computers also consider ATC charges and overflight fees which could vary significantly depending on the countries overflown? If elapsed times were roughly the same for different routings, they might pick the routing with the lowest ATC and overflight charges to minimize costs.

[Edited 2008-01-04 16:22:24]

User currently offlineIkramerica From United States of America, joined May 2005, 21582 posts, RR: 59
Reply 7, posted (6 years 11 months 3 weeks 20 hours ago) and read 8316 times:



Quoting Viscount724 (Reply 6):
I wonder if fllight planning computers also consider ATC charges and overflight fees which could vary significantly depending on the countries overflown

Well, somebody does. Again, notice how the routes avoided flying over Russia...  Wink

It's similar to how CO routes it's flights to/from IAH/HNL. In general, they fly along the US/Mexico border and leave the USA over San Diego (and vice versa). But if there is a major storm sitting over the southwest or the jetstream drops nastily over New Mexico, they will route over Mexico and pay the expensive overflight fees.



Of all the things to worry about... the Wookie has no pants.
User currently offlineLAXdude1023 From India, joined Sep 2006, 7808 posts, RR: 25
Reply 8, posted (6 years 11 months 3 weeks 20 hours ago) and read 8268 times:



Quoting Ikramerica (Reply 2):
Probably winds combined with not wanting to route over the poles if diversion airports are too cold for comfort. It's the peak of northern winter, where the jetstream is very strong and the arctic very cold, so riding the winds while avoiding the poles is a good plan if possible.

Ive never done a polar route before. Is it smoother or bumpier than say flying over the Pacific?



Stewed...Lewd...Crude...Irreverent...Belligerent
User currently offlineWarren747sp From United States of America, joined Feb 2004, 1171 posts, RR: 0
Reply 9, posted (6 years 11 months 3 weeks 18 hours ago) and read 8080 times:

I would have to say the Polar route is smoother than the route direct over the Pacific. It is always rought from Japan-Honolulu or using the jetstream to cross the Pacific from Asia departure cities.


747SP
User currently offlineCoal From United States of America, joined Aug 2006, 2129 posts, RR: 10
Reply 10, posted (6 years 11 months 3 weeks 18 hours ago) and read 8012 times:

Incidentally, it was so turbulent over the atlantic that all pax in the aft Business section were awake and the lights went back on.

Cheers
Coal



Nxt Flts: SQ SYD-SIN-DEL-SIN-SYD | VA SYD-DPS-SYD
User currently offlineLAXdude1023 From India, joined Sep 2006, 7808 posts, RR: 25
Reply 11, posted (6 years 11 months 3 weeks 17 hours ago) and read 7966 times:



Quoting Coal (Reply 10):
Incidentally, it was so turbulent over the atlantic that all pax in the aft Business section were awake and the lights went back on.

Sounds about right for flights over the atlantic this time of year. Its always smoother in the spring and summer.

Quoting Warren747sp (Reply 9):
I would have to say the Polar route is smoother than the route direct over the Pacific. It is always rought from Japan-Honolulu or using the jetstream to cross the Pacific from Asia departure cities.

Ive taken LAX-SIN nonstop on SQ in April of last year. It wasnt rough until we got between Taiwan and Phillipeans. I think it also depends on the time of year. In April-Oct Ive always good rides over the Pacific. From late Nov to the begginning of March ive always had bumpy Pacific crossings. Ive heard going to South America is the opposite. During the Northern winter its supposed to be smooth whereas the northern winter gives bumpy rides over the Atlantic and the Pacific.



Stewed...Lewd...Crude...Irreverent...Belligerent
User currently offlineIkramerica From United States of America, joined May 2005, 21582 posts, RR: 59
Reply 12, posted (6 years 11 months 3 weeks 17 hours ago) and read 7894 times:



Quoting LAXdude1023 (Reply 8):
Is it smoother or bumpier than say flying over the Pacific?

I don't see how it could be any worse...  Wink



Of all the things to worry about... the Wookie has no pants.
User currently offline3201 From , joined Dec 1969, posts, RR:
Reply 13, posted (6 years 11 months 3 weeks 16 hours ago) and read 7810 times:



Quoting Viscount724 (Reply 6):
I wonder if flight planning computers also consider ATC charges and overflight fees which could vary significantly depending on the countries overflown? If elapsed times were roughly the same for different routings, they might pick the routing with the lowest ATC and overflight charges to minimize costs.

Yes

Check out this thread:
UK Airlines Fly The Long Way To The Canary Islands (by Gilesdavies Dec 3 2007 in Civil Aviation)

Quoting Ikramerica (Reply 7):

Well, somebody does. Again, notice how the routes avoided flying over Russia...

Not necessarily due to overflight charges.


User currently offlineBOStonsox From United States of America, joined Dec 2007, 1995 posts, RR: 0
Reply 14, posted (6 years 11 months 3 weeks 15 hours ago) and read 7732 times:

I think that winds have pretty much everything to do with it. At the latitude New York is at the majority of winds go east anyway but they go south when you near the north pole. Since you'd be resisting the winds by going straight north you are probably better off just heading east and staying south of the winds. Although even for that reason those routes were very far off the most direct route. I think a lot of that is because at this time of year you have more wind coming from the North Pole. Also, I wonder how many airports are along the route that can both land the plane you flew on in the case of emergency and are within the 138-minute ETOPS region.


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User currently offline3201 From , joined Dec 1969, posts, RR:
Reply 15, posted (6 years 11 months 3 weeks 15 hours ago) and read 7687 times:



Quoting BOStonsox (Reply 14):
but they go south when you near the north pole.

Every direction is south when you near the north pole.  Silly


User currently offlineNorcal773 From United States of America, joined Feb 2007, 1451 posts, RR: 12
Reply 16, posted (6 years 11 months 3 weeks 15 hours ago) and read 7666 times:



Quoting Ikramerica (Reply 5):
They avoided flying over Russia in both directions if nothing else...



Quoting Viscount724 (Reply 6):
I wonder if flight planning computers also consider ATC charges and overflight fees which could vary significantly depending on the countries overflown? If elapsed times were roughly the same for different routings, they might pick the routing with the lowest ATC and overflight charges to minimize costs.

A little out of topic but what's the deal with flying over Russia? I thought it was ridiculous over-fly fees until Jan 1st when I flew SFO-IN on SQ 15. We pushed back 15 minutes late and the captain said it was because of 'Russian Airspace regulations'. We Taxied to 28L and held short of the runway for another 15 minutes and the captain came on again and said this was because of 'Russian Airspace regulations'. This left me all confused. It was interesting watching other planes take the long route to the 28's for takeoffs because we were sitting there just blocking the way.



If you're going through hell, keep going
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 17, posted (6 years 11 months 3 weeks 15 hours ago) and read 7631 times:



Quoting Norcal773 (Reply 16):
We pushed back 15 minutes late and the captain said it was because of 'Russian Airspace regulations'. We Taxied to 28L and held short of the runway for another 15 minutes and the captain came on again and said this was because of 'Russian Airspace regulations'

There are flow restrictions along the Russian routes. The overflight fees aren't the real issue.


User currently offlineNorcal773 From United States of America, joined Feb 2007, 1451 posts, RR: 12
Reply 18, posted (6 years 11 months 3 weeks 15 hours ago) and read 7584 times:



Quoting PhilSquares (Reply 17):
There are flow restrictions along the Russian routes.

What's 'flow restriction'? Thanks by the way.



If you're going through hell, keep going
User currently offlineCOEWR787 From United States of America, joined Mar 2005, 339 posts, RR: 3
Reply 19, posted (6 years 11 months 3 weeks 15 hours ago) and read 7570 times:

I have flown EWR-SIN-EWR three times now by SQ. Of the 6 legs, two were over the pole and the rest were all southerly. Idle chat with a flight crew suggested that the ratio is about right, i.e. about a third of the flights take the polar route. Mostly depends on the wind situation on the day according to the guy that I talked to.

User currently offline3201 From , joined Dec 1969, posts, RR:
Reply 20, posted (6 years 11 months 3 weeks 14 hours ago) and read 7562 times:



Quoting Norcal773 (Reply 16):
A little out of topic but what's the deal with flying over Russia? I thought it was ridiculous over-fly fees until Jan 1st when I flew SFO-IN on SQ 15. We pushed back 15 minutes late and the captain said it was because of 'Russian Airspace regulations'. We Taxied to 28L and held short of the runway for another 15 minutes and the captain came on again and said this was because of 'Russian Airspace regulations'.

Permission to overfly Russia is for specific routes, and probably for specific time windows. It can be cheaper to hold on the ground than to fly slower if you're going to arrive at their airspace too early.


User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3597 posts, RR: 66
Reply 21, posted (6 years 11 months 3 weeks 14 hours ago) and read 7553 times:



Quoting BOStonsox (Reply 14):
I think a lot of that is because at this time of year you have more wind coming from the North Pole. Also, I wonder how many airports are along the route that can both land the plane you flew on in the case of emergency and are within the 138-minute ETOPS region.

Well, he was on a Quad (A345) so the ETOPS rules did not apply. And if it had been a suitably equipped Twin, the diversion time would have been in the 180/207 min. ETOPS category. There are several suitable airports that are within a 180/207 min area of operations from the North Pole. The attachment shows the 180 min area of operations.

http://gc.kls2.com/cgi-bin/gc?PATH=s...GE-COLOR=navy&MAP-STYLE=&ETOPS=180



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 22, posted (6 years 11 months 3 weeks 14 hours ago) and read 7391 times:



Quoting Norcal773 (Reply 18):
What's 'flow restriction'? Thanks by the way.

Flow restrictions are basically the number of aircraft/hour or aircraft/flight level that can operate the route. The Russian airspace has some sever capacity limits on it and they require 15 minutes in trail separation for the same flight level. Quite a bit of the route is published as non-radar which increases the separation requirements.


User currently offlineJacobin777 From United States of America, joined Sep 2004, 14968 posts, RR: 59
Reply 23, posted (6 years 11 months 3 weeks 14 hours ago) and read 7363 times:



Quoting Ikramerica (Reply 5):

Not important. The shortest path between two points isn't always the best. If the path you flew took advantage of very high tail winds (100 knots) then the 8 hours it was in this path would make up for the 800 extra nm flown.

Add to that that going up over the pole may even have meant going against the wind for an amount of time, meant plotting for dangerous diversions in the peak of winter, and paying russian overflight fees, it was likely better to fly the way SQ flew it. They avoided flying over Russia in both directions if nothing else...

IIRC.there was some talk before of QF possibly doing SYD-LHR via TPAC-Alaska-TATL had they purchased the -200LR....I don't remember if it was just "A.net chat" or not, but I do recall something about it..

Quoting Norcal773 (Reply 16):
This left me all confused.

...what's new?  duck 



"Up the Irons!"
User currently offline3201 From , joined Dec 1969, posts, RR:
Reply 24, posted (6 years 11 months 3 weeks 13 hours ago) and read 7126 times:



Quoting OldAeroGuy (Reply 21):
The attachment shows the 180 min area of operations.

What diversion airspeed is that using? The plot won't look the same for every aircraft type (and in fact Boeing will show different pictures for 777 and 747 because they have different airspeeds, so the 180-minute contours are different distance from the divert airfields)


25 Post contains images Chrisrad : In 2006 I flew TG JFK-BKK non-stop we went practically straight over the pole, emerged through Russia (which I heard charges an exhorbitant over-flyin
26 Theginge : Yes a lot consider this along with enroute weather, airspace closures etc etc. They can work out the most cost effective route. Sometimes the cheapes
27 AwysBSB : What infrastructures are required at the bases of ultra-long-haul routes? I have heard it is necessary a lab that examines fuel density for flight pla
28 Irish251 : Singapore's EWR-SIN flight is a very regular sight over Dublin, Ireland so even the route that Coal's flight took is somewhat more southerly than the
29 OldAeroGuy : 400 kts true airspeed. It represents an indicated airspeed of about 345 kts (0.627M) at FL100. This is where all airplanes will be after a decompress
30 Post contains links Evan767 : It all depends on the winds. We flew wayyy out of our way from DUB to ATL in December. We flew up over Belfast, just under Iceland, right under Godtha
31 Post contains images Ikramerica : But you still have to plan for diversions, and if there are no suitable airports along the route, you got a problem. If it's -40 and blizzard at your
32 OldAeroGuy : But there are many suitable diversion airports on the Polar routes within 180 min. And Quads do not need to land at the nearest suitable airport, eve
33 3201 : This may be a good rule of thumb, but actual airspeeds used for these calcs vary by aircraft type, agreement with regulator, etc. It hurts the 767 an
34 OldAeroGuy : So, what do you think the variation of ETOPS diversion true airspeeds is, highest to lowest? And what ETOPS diversion rule are you applying to the 74
35 3201 : With the number of airports available and the amount of fuel on that aircraft for the planned route, there's no way the diversion would be an issue.
36 Dispatchguy : I believe that Singapore uses the SABRE system, and it does calculate the overflight charges, and it does consider the overflights when doing a minim
37 3201 : New FAA ETOPS rules apply to 747 beyond 180 mins. From FAR 121.7: ETOPS Area of Operations means one of the following areas: ... (2) For turbine-engi
38 OldAeroGuy : Which is why I asked the question. There are plenty of suitable airports within 180 min on the polar routes using 400 KTAS, which is probably a bit c
39 Post contains images 3201 : I don't know either. There's competitive pressure on other regulators to meet the parts of the FAA rules that offer reduction in critical fuel requir
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