Sydney to Perth

[solissydney]

Flying from Sydney to Perth takes less time than the return trip,why?
At the Equator Earth spins anti clockwise at the speed of 1,667 ks an hour, this rotational speed get less and less the closer south you are, until at the pole it falls to nothing. This of course means that as you fly from Sydney toward Perth, Perth travels towards you making the trip shorter. How much of a role does the Jet Stream play?
I can't find anything concrete on the web about the Jet Stream over NSW.
Is the Jet stream always in the same place or does its change position in the sky?

Ken

[DaveR]

Ken,
Ignoring the time zone shift it is normally much quicker West to East and this is mostly the jetstream. It varies during the year but can also vary greatly within a week. My best time from Perth to Melb was about 2 hours 40, can take much longer going the other way (3 :40 last Friday). Pilots also vary the ground track and altitude as they try to use or avoid. Once flew Syd - Perth and the track (according to the pilot) nearly clipped the top corner of Tasmania before heading to Perth.

Air traffic control can also add time as they slow down and space planes coming into controlled air space.

Cheers

Dave

[bloodhound31]

I have always found that the predominant weather patterns travel from west to east in our part of the world, kind of like flying with the wind from Perth to Sydney, or against going the other way. I have done this many times in commercial airlines at high altitude as well as Hercules and Caribou military Jet-Turbine and propeller driven aircraft.

Baz.

[solissydney]

Ooops, got it back to front.
Interesting thing, the Jet Stream.

The Jet stream.
Huge volumes of air of different temperatures are rising and falling at the point where the two cells meet and the boundary shifts constantly, waving snake-like, north and south, as one cell expands against the other, only to contract as pressure builds on the other side. This is not a fixed line around the world but, if it could be made visible, would be more akin to an ever-changing battleground where one army pushes polewards with reinforcements of warm air, only to be repulsed by greater quantities of cold pressing the other way. The result is to create huge differences in pressures in the air aloft, and just as any wind on the ground is created by differences in pressure between blocks of air, so very strong winds build up at the top of the boundary, creating fast-moving rivers of air that encircle the planet. These are the Jet Streams, current of air typically hundreds of kilometers long, 100 kilometers wide and a kilometer or more deep, which can reach speeds of 300-500 kilometers per hour.

Taken from the book 'Wild Weather'. BBC TV series

Ken

[mithrandir]

1980 and flying Perth -> Sydney the midnight special left Perth about 01:00 WST after sitting on the tarmac for about half an hour, throttled back to idle over Broken Hill, and still hit Sydney before the 06:00 EST curfew.

That's a jet stream.

FYI, it's a hour faster direct Sydney->San Francisco than SF->Sydney. Also it's faster to SF than LA.

[pgc hunter]

I remember back in 1999 flying Vienna-KL-Melbourne on a Boeing 777 reaching a top speed of 1132km/h, which, assuming no wind, would be close to Mach 1. That must;ve been one hell of a jetstream.