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Coal
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Why SQ’s Southerly Route On EWR-SIN Non-stop?

Fri Jan 04, 2008 10:04 pm

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: MI RGN-SIN | SQ SIN-RGN-SIN | CX SIN-HKG-PVG | SQ PVG-SIN
 
mpdpilot
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Fri Jan 04, 2008 10:52 pm



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.
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ikramerica
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Fri Jan 04, 2008 11:11 pm

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.
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Coal
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Fri Jan 04, 2008 11:48 pm

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: MI RGN-SIN | SQ SIN-RGN-SIN | CX SIN-HKG-PVG | SQ PVG-SIN
 
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Fri Jan 04, 2008 11:52 pm



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?
 
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 12:01 am



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...
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Viscount724
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 12:07 am

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]
 
ikramerica
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 12:13 am



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.
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 12:28 am



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?
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warren747sp
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 2:09 am

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.
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Coal
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 2:38 am

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
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LAXdude1023
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 2:53 am



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.
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ikramerica
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 3:14 am



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
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 3:59 am



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.
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BOStonsox
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 4:55 am

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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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 5:15 am



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
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Norcal773
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 5:25 am



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.
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 5:34 am



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.
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 5:46 am



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

What's 'flow restriction'? Thanks by the way.
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COEWR787
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 5:50 am

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.
 
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 5:56 am



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.
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OldAeroGuy
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 6:01 am



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
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 6:37 am



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.
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 6:42 am



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.

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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 7:39 am



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)
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chrisrad
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 8:46 am

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-flying fee). Ride was the smoothest I have had over the 17 hours



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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 1:13 pm



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 a lot consider this along with enroute weather, airspace closures etc etc. They can work out the most cost effective route. Sometimes the cheapest route is not always the best one to take.
 
AwysBSB
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 3:39 pm

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 planning.
What other requirements have to be met?
 
iRISH251
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 3:59 pm

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 norm, I'd say. Both Qatar and Emirates are also regular sights with their non-stop services between the Middle East and the USA.
 
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 4:16 pm



Quoting 3201 (Reply 24):
What diversion airspeed is that using?

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 decompression unless they are carrying enough passenger oxygen to extend cruise at a higher altitude.

This speed is a good rule of thumb as all airplanes that are likely to be flying a polar route will be able to maintain it at FL100 even with one engine inoperative.
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Evan767
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 6:16 pm

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 Godthab, over the Hudson Bay, down lake Michigan barely clipping Chicago, and coming in to ATL from the west.
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ikramerica
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 6:37 pm



Quoting OldAeroGuy (Reply 21):
Well, he was on a Quad (A345) so the ETOPS rules did not apply.

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 customary polar diversion, you have to plan something else.

Quoting Jacobin777 (Reply 23):
I don't remember if it was just "A.net chat" or not,

It was a.net chat, as it's 2000nm further and you'd need to average 100nm wind bonus for the 20 hours of flight. Not impossible, but unlikely most of the year.

Quoting Chrisrad (Reply 25):
In 2006 I flew TG JFK-BKK non-stop we went practically straight over the pole

Was it summer?

Quoting Evan767 (Reply 30):
right under Godthab, over the Hudson Bay, down lake Michigan barely clipping Chicago, and coming in to ATL from the west.

Well, that makes sense. Rather than fight the jetstream into the east coast they flew around/across it, then jumped it for a tailwind into ATL. This would happen when the stream is avoiding the west coast and dropping deep into the USA from Canada at about North Dakota. This also usually means it's either warmer or raining here in Los Angeles.  Smile
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OldAeroGuy
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 7:30 pm



Quoting Ikramerica (Reply 31):
Quoting OldAeroGuy (Reply 21):
Well, he was on a Quad (A345) so the ETOPS rules did not apply.

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 customary polar diversion, you have to plan something else.

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, even after a major failure such as an IFSD. This gives them plenty of options as to picking a diversion airport.
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3201
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 9:16 pm

Quoting OldAeroGuy (Reply 29):
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 decompression unless they are carrying enough passenger oxygen to extend cruise at a higher altitude.

This speed is a good rule of thumb as all airplanes that are likely to be flying a polar route will be able to maintain it at FL100 even with one engine inoperative.

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 and helps the 747 and has a moderate effect on everything in between.

In any event, I completely agree that there's no way that diversion considerations are responsible for the route the OP questioned.

[Edited 2008-01-05 13:54:07]
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OldAeroGuy
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 9:54 pm



Quoting 3201 (Reply 33):
It hurts the 767 and helps the 747 and has a moderate effect on everything in between.

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 747?
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
3201
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sat Jan 05, 2008 9:59 pm



Quoting Ikramerica (Reply 31):

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 customary polar diversion, you have to plan something else.

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. While they do need to do some analysis to ensure they have enough fuel if they have decompression and/or engine loss, there's no limit to how far they're allowed to fly to meet that requirement.
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dispatchguy
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sun Jan 06, 2008 12:36 pm



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.

I believe that Singapore uses the SABRE system, and it does calculate the overflight charges, and it does consider the overflights when doing a minimum cost flight plan. I know that Cathay Pacific uses SABRE (or at least used it as of a couple of years ago).

I think its interesting, that everytime this aircraft departs WSSS for the KEWR turn, it is going around the world, for I have never seen the WSSS-KEWR segment go westbound.
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3201
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Sun Jan 06, 2008 7:05 pm



Quoting OldAeroGuy (Reply 34):
And what ETOPS diversion rule are you applying to the 747?

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-engine-powered
passenger-carrying airplanes with more
than two engines, an area beyond 180
minutes from an adequate airport,
computed using a one-engine inoperative
cruise speed under standard
conditions in still air.

There's no maximum distance for a 3- or 4-engine aircraft, but it's possible operators may try to remain within 180 minutes of adequate airports so they don't have to deal with all the ETOPS stuff. However, that's a static calculation, the adequate airports I think don't need to have good conditions (so the -40F and blizzard is no factor). Also I think this is not necessarily at a decompression altitude, so the speed is higher than it might otherwise be.

There is a requirement, however, 121.646, to ensure there's enough fuel to divert with a decompression even if you have more than 2 engines. Again, on a EWR-SIN there should be enough fuel that this isn't an issue no matter what route you fly, since as you get closer to SIN there are plenty of airports, and again there's no max distance or time for this diversion, you just need to have enough fuel.

Quoting OldAeroGuy (Reply 34):
So, what do you think the variation of ETOPS diversion true airspeeds is, highest to lowest?

Good question. I've seen Boeing use a number 18% higher for a 744 than a 777, and a 767 should have a bigger gap downward from the 777. My understanding, though, is an "approved airpseed" is between the operator and their POI in the FAA world, and outside the FAA world similarly decided, so I don't know whether the Boeing numbers actually get used or not. Airbus is in the odd situation that for years they lobbied for more conservative ETOPS rules but now with the 330 and 350 being at least as important as their quads to their sales, I assume they have to do an about-face and try to lobby for more capability for twins.
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OldAeroGuy
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Mon Jan 07, 2008 1:52 am



Quoting 3201 (Reply 37):
Quoting OldAeroGuy (Reply 34):
And what ETOPS diversion rule are you applying to the 747?

New FAA ETOPS rules apply to 747 beyond 180 mins.

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 conservative for the 747 considering its diversion speed potential. Thus the new FAA ETOPS rules would not be invoked.

As to the ETOPS rule being used though, I'm not sure that the Singapore CAA is using the new FAA ETOPS rules yet.

Quoting 3201 (Reply 37):
Airbus is in the odd situation that for years they lobbied for more conservative ETOPS rules but now with the 330 and 350 being at least as important as their quads to their sales, I assume they have to do an about-face and try to lobby for more capability for twins.

Yes, it is a bit ironic, especially when you consider some of the Airbus advertising in the late '90s.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
3201
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RE: Why SQ’s Southerly Route On EWR-SIN Non-stop?

Mon Jan 07, 2008 3:02 am



Quoting OldAeroGuy (Reply 38):

As to the ETOPS rule being used though, I'm not sure that the Singapore CAA is using the new FAA ETOPS rules yet.

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 requirements for twins, but no real reason for them to rush to introduce new restrictions.  Smile

Most of the major regulators are planning to do something this year I think (the ones that haven't already).

I'll repeat again, though, and I know OAG and I agree on this: no way was diversion airports in any way a factor on which way that SQ EWR-SIN flight routed, absolutely no way.
7 hours aint long-haul

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