nummi
Topic Author
Posts: 2
Joined: Thu May 18, 2017 4:06 pm

Flight Routing SFO to PVG

Thu May 18, 2017 4:11 pm

Hi All,
I have been looking at the routing for United 857 from SFO to PVG. It seems that some days the flight flies north of the Korean peninsula, over China and then down to PVG. Other times it goes south of the peninsula and over Japan before heading for PVG. Is this only due to the headwinds? Or are there other reasons?
Thanks
 
RetiredWeasel
Posts: 460
Joined: Sat Jul 05, 2014 8:16 pm

Re: Flight Routing SFO to PVG

Thu May 18, 2017 6:03 pm

Since the image shows the shortest route, I would guess a more northerly route over china would be flight planned by the computers to avoid head winds.
Image
 
BravoOne
Posts: 1935
Joined: Fri Apr 12, 2013 2:27 pm

Re: Flight Routing SFO to PVG

Thu May 18, 2017 9:09 pm

It can be a combination of overflight issues along with winds. There are incredible
winds at certain times of the year. Often referred to a a "wall of wind" as they frequently exceed 200-250Kts. Operators will go out of there way and take routings that minimize these winds. A lot of flight plans will show the total distance in nautical lines from departure to destination along with the nautical air miles (NAM) which factor in both headwinds and tailwinds. On a route such as Weasel has shown, the difference can be 200 or more miles.
 
MSJYOP28Apilot
Posts: 320
Joined: Tue Jul 21, 2009 2:09 am

Re: Flight Routing SFO to PVG

Fri May 19, 2017 3:37 am

It really depends on several factors. Jetstreams can set up in a variety of different areas. The cheapest way for this flight to go would be on one of the PACOTS, which change every day based on the winds, or an R220 routing. Going through Russia and China can sometimes be the best wind route or it can be a route to avoid volcanic activity. Sheveluch has been pretty active and this can make an R220 routing not a good idea and to be on the conservative side many carriers go farther north to avoid it. Going through Russia and China incurs a higher overflight fee cost than the routing on R220 or the PACOTS. Sometimes turbulence and storm systems can be a factor in the routing.

One thing about China, Japan and Russia is that the routings are a lot stricter than operating in US airspace. You need to stay on the airways and the airways and fixes you use are negotiated with the governments of those countries and the airlines. Some are more liberal like Japan and South Korea but others like Russia and China require certain airways and fixes. Thus if you want to go around some weather it can require a long detour.
 
RetiredWeasel
Posts: 460
Joined: Sat Jul 05, 2014 8:16 pm

Re: Flight Routing SFO to PVG

Fri May 19, 2017 3:59 am

MSJYOP28Apilot wrote:
It really depends on several factors. Jetstreams can set up in a variety of different areas. The cheapest way for this flight to go would be on one of the PACOTS, which change every day based on the winds, or an R220 routing. Going through Russia and China can sometimes be the best wind route or it can be a route to avoid volcanic activity. Sheveluch has been pretty active and this can make an R220 routing not a good idea and to be on the conservative side many carriers go farther north to avoid it. Going through Russia and China incurs a higher overflight fee cost than the routing on R220 or the PACOTS. Sometimes turbulence and storm systems can be a factor in the routing.

One thing about China, Japan and Russia is that the routings are a lot stricter than operating in US airspace. You need to stay on the airways and the airways and fixes you use are negotiated with the governments of those countries and the airlines. Some are more liberal like Japan and South Korea but others like Russia and China require certain airways and fixes. Thus if you want to go around some weather it can require a long detour.


Eloquently said. I was trying to keep it simple by stating that winds are the most common reason for the selected routing. Anything to save a few pounds of fuel.

Talked to jumpseating dispatcher once, and seem to remember that he said the computers that build the flight plans not only take into account all the weather factors, but also do the cost analysis using overflight fees. However there were plenty of options to manually input factors such as volcano deviations, overflight political problems, anticipated late takeoffs (bump up the mach a little) and many others. Way beyond my old EB6 whiz wheel computer days.
 
Adispatcher
Posts: 47
Joined: Sun Dec 11, 2016 11:52 pm

Re: Flight Routing SFO to PVG

Sat May 20, 2017 8:08 pm

There has been lots of volcanic activity in the Kamchatka Peninsula lately which is pushing operators north and away from the ash cloud.

Often, a non-Russian routing is cheaper in overflight fees, but more in fuel burn. If you're not payload critical it is often easier to file on the NOPACs and come down to Asia via Japan. If there is a heavy load, you can save fuel and increase your payload capacity by filing further north over Russia, however you will pay significantly more in overflight fees. Outside of weather and other considerations, it is flight dependent.
 
nummi
Topic Author
Posts: 2
Joined: Thu May 18, 2017 4:06 pm

Re: Flight Routing SFO to PVG

Mon May 22, 2017 11:31 pm

Thanks all for the responses! Exactly what I was curious about.

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