Two questions on long airline flights

[NewJeffCT]

Since I returned went back & forth to China for the second time, I was wondering if people that have also been on long flights - or those folks that are more knowledgeable than me, but maybe haven't been on the long flights - can fill me in on a couple of questions.

1) The two times I left the US, I flew from LA and Chicago and both times, the flight path from LA was almost like a parabola - we went up the west coast, over Alaska, down near Siberia and then into Shanghai. It was similar from Chicago, only the parabola was not as dramatic. I thought of a couple of reasons why - a) they did not want to be too far from land in case of emergency; or b) something to do with the earth's curvature. But, I figured a straight line out over Hawaii would be quickest? (the flights were similar parabolas (parabolae?) coming back.)

2) On the way back from China, they kept the passengers on Chinese time, meaning they served breakfast to the passengers two hours before we landed in Chicago - even though it was 2pm Chicago time. Why is that? Shouldn't they be helping you adjust to your new time zone? They also kept the plane dark, even though it was morning, and then afternoon - though, it was night in China... however, on the way TO China, they did not darken the lights when it was night time in Chicago. (this was American Airlines, if you were wondering)

[mainegreen]

1. Your post is too long so I will just glaze over it and give you this answer:

You need to eat more beans before you fly.
This will solve your problem.

[bicentennial_baby]

2. My flights to and from Paris were similar...

From NYC, up over Maine and Newfoundland, across the Atlantic, then down over Ireland and England to France. Weird. :shrug:

[Gormy Cuss]

7. My non-Euclidean geometry class was where I learned about great circles.

In spherical geometry, the shortest distance between two points is a curved line passing through a pole.

Don't quote me on this, I'm working from memory but as I recall a "great circle" of the earth has a point on the line at each of the two poles.

[MonkeyFunk]

3. OK

to answer #1, it's the shortest distance between two points on a sphere. It's the Great circle distance:

http://en.wikipedia.org/wiki/Great-circle_distance

As to #2, I just presume they always stay on local time at the point of departure until they land. Every flight I've taken to or from the US worked that way.

[billyskank]

4. The shortest route is not a straight line parallel to the equator

It only looks that way on a map. Remember that the Earth is a sphere. Draw a line from your starting point to the Earth's core. Now do the same with your destination. The shortest route between them is the edge of the sector of a circle that is swept out by those two radii.

Does that make any sense? Anyway, it means if you're flying from the States to Europe (or China) then the shortest route actually takes you up past the Arctic Circle.

[havocmom]

5. Yep. And being as how I am from Missouri, a teacher used globe and string to show me

It just didn't seem logical, but the arc route is shorter.

[pokerfan]

12. Great Circle Mapper

Input the starting/ending airport codes and this applet will show the great circle route.
http://gc.kls2.com/

Yep, the easiest way to visualize it is with a globe and some string.

If you've ever seen a shuttle orbit (or that of any satellite), they are by definition great circle routes:

[Commie Pinko Dirtbag]

15. Cool site, and -- lo and behold, take a look at the LAX -> PEK optimal route!

[pokerfan]

16. Also applies to the Clipper sailing route

http://en.wikipedia.org/wiki/Clipper_route#Outbound

Once into the forties, a ship was also inside the ice zone, the area of the Southern Ocean where there was a significant chance of encountering icebergs. Safety would dictate keeping to the north edge of this zone, roughly along the parallel of 40 degrees south; however, the great circle route from the Cape of Good Hope to Australia, curving down to 60 degrees south, is 1,000 miles shorter, and would also offer the strongest winds. Ship's masters would therefore go as far south as they dared, weighing the risk of ice against a fast passage.

[NewJeffCT]

19. thanks - cool site

I remember once, the flight was delayed a few minutes because they had to get clearance to fly over Russian airspace...

[billyskank]

14. Ah yes, an "arc." That was the word I was searching for.

What do they call the edge of a sector? An arc! Thank you.

[Redstone]

6. Bingo! It's called a Great Circle Route.

Redstone

[huskerlaw]

8. Yep...

Same thing on the way to-from Europe.

As others have mentioned, it's less distance up closer to the poles. We flew from LA, up past North Dakota and over Canada, then Greenland, and back down over Ireland to the continent.

As for the eating/sleeping thing...they kept us on the schedule of the time zone we were leaving both directions. Left LA at 6:30 pm, got dinner and then they turned the lights out. We got breakfast shortly before landing in Switzerland, though it was afternoon there. On the way back, we left Zurich mid-afternoon. We got dinner and the lights stayed on. Though by the time we landed in LA, it was approaching midnight Zurich time (mid-afternoon in LA). But I don't suppose they wanted to turn the lights off with so little time left in the flight.

[Gormy Cuss]

9. On your second question, I think that it's easier to adjust after experiencing 'night'

(because sleeping helps reset your clock)and maybe on the very long flights the airlines have adopted this practice to help passengers transition. As I recall west to east is considered a harder adjustment than east to west, but I may be wrong there.

[SKKY]

10. If you went on a straight line from LA to Shanghai, you would end up way north...

...(or is it south?) due to the Coriolis effect. It's for the same reason if you started out on a straight line from Chicago to Mexico City for example, you would end up way west of Mexico City.

[billyskank]

11. No, the coriolis effect only affects north/south journeys.

It is because when you are very high up north or very far down south, you have relatively low angular momentum due to the short perpendicular distance from the Earth's axis of rotation.

As you move towards the equator, you move further and further away from the polar axis, and therefore you start to 'slip' behind the Earth's rotation, just as a gymnast or a high diver spins slower when they stretch out than they do when they curl up.

This causes aeroplanes to slip west when they fly directly away from the equator, and slip east when they fly directly towards it from one of the poles. Not that this happens much; most long haul flights go mostly from east to west or vice versa.

Supposedly the coriolis effect makes north/south-flowing rivers erode more on one bank than the other. This I can just about believe. I also heard it makes north/south railways wear out one rail faster than the other, but I have difficulty believing this.

[bicentennial_baby]

13. You just broke my brain....

x(

[SKKY]

17. The Coriolis effect has no impact at all on east/west journeys?

Hmmm. I could have sworn it did, assuming of course you were not on a perfect line east to west. Either way, the point I missed here was that, her route was much faster than on a straight line due to the equator and circumference and all that.

[trof]

18. No no no, the Coriolis Effect is what makes the water

drain counter-clockwise out of the tub in Australia.
;-)

[kay1864]

20. !

:rofl:

You forgot the sarcasm smiley :hi: