Given that earth is rounded, why there is no quick flights from Japan to America?

[Colophon]

@standingwave

Very cool. Here’s a screenshot of my water world. The pin is Bora Bora.

Cool. If you zoom waaaaay in you can just make out Kevin Costner.

[Una_Persson]

@Giles

My one trip between Japan and the U.S. was between Osaka and Detroit. With that, the shortest route is via Alaska, and that’s basically because the Earth is round.

I’ve been on that same flight.

[Chronos]

Not really a complete hemisphere because of perspective. (You’re seeing the Earth from a finite height.) It’s close, though. You’d have to be infinitely far away to see half of a sphere.

Technically, about half a lightyear is far enough, due to gravitational lensing. Further than that, and you’ll actually see more than half of the planet.

[GusNSpot]

@StrangerThanFiction

I don’t know how it was done back in the day, but I have an educated guess. When we make oceanic crossings, we keep a paper chart with of all of our waypoints plotted on it. For a north Atlantic crossing, we will typically have a waypoint at each fifth degree of longitude. We keep our paper chart updated with our current position in case we lose all forms of long range navigation and have to dead reckon (heading + wind = ground track) along our planned route back to landfall. Let’s say we have two waypoints along the same line of latitude and five degrees of longitude apart. The initial eastbound heading might be 088. Halfway along the leg, the heading will be 090. When we arrive at the second waypoint, our heading will be 092. Had we flown 090 the whole time, we would have ended up in the same place, but it would have taken slightly longer. So we can take the headings from the mid points of each “short” leg and use them one after another to approximate a great circle route in a crude manner. If everything goes to plan, the flight guidance computers will constantly update our heading to account for this, as well as correcting for the actual winds. Our long range nav equipment is certified to guarantee us to be within 4 nautical miles of a given point 95% of the time. In reality, the five independent nav sources on my airplane typically agree to within a few feet.

To answer your question, I would think that a once-an-hour check would be sufficient on an airplane only moving at 200-300 knots, but back then airplanes carried navigators. His whole entire job was to tell the pilot what heading to fly, so my assumption would be that he had nothing better to do than to recalculate the winds and the estimated time for the next 1 degree heading change over and over again.

Well, actually, if you were not good with a sextant, you would not be the navigator. They worked their asses off. Many of the early long haul birds actually had bubbles for the navigator to use to get his reading. Also a lot of the long ocean passages tried to do a lot of it at night so as to use stars so the navigation would be more on course.
In doing aerial mapping where straight line E/W tracks were followed after the advent of cheap LORAN, on a long track, like clear across Kansas, the heading change would be noticeable.

Also, when the GPS tracks became more common. The route it took was always great circle and if you had drawn a line on a map, it was obvious the LORAN or GPS was taking what looked like a curved route that was longer. It was sometimes hard to get folks to understand until you get them to a round globe with a piece of string.

Then to really mess with them, a straight ground track N/S would leave the GPS heading steady and the magnetic heading would get off. Unless you were real close to the 0° variation line where magnetic & true North are pretty much the same in the US.

[standingwave]

@Chronos

Technically, about half a lightyear is far enough, due to gravitational lensing. Further than that, and you’ll actually see more than half of the planet.

I’m not really seeing how that geometry would work.

[Kevbo]

Given that you land several hours earlier than you took off * when flying from the Japan to the US, I can’t imagine why this is not fast enough for the OP.

*You cross the international date line, and in so doing, it becomes yesterday.

[brittekland]

@Kevbo

Given that you land several hours earlier than you took off * when flying from the Japan to the US, I can’t imagine why this is not fast enough for the OP.

*You cross the international date line, and in so doing, it becomes yesterday.

So, in turn, you either arrive at pretty much the same time and date you left Japan or, even land before the time and date you left! Now that’s time travel.

How can one fly faster than arrive before you actually left??

[Chronos]

I’m not really seeing how that geometry would work.

Let’s say you’re half a lightyear above the North Pole, for simplicity. Now take rays of light that start from the equator, tangent to the surface. In a Newtonian universe, those rays would remain parallel forever, but in an Einsteinean universe, they’re deflected slightly by the mass of the Earth. Because of this deflection, those initially-parallel rays eventually cross, about a half lightyear away, and so an observer at that point could see both of them (hence, seeing half the surface of the Earth).

[standingwave]

@Chronos

Let’s say you’re half a lightyear above the North Pole, for simplicity. Now take rays of light that start from the equator, tangent to the surface. In a Newtonian universe, those rays would remain parallel forever, but in an Einsteinean universe, they’re deflected slightly by the mass of the Earth. Because of this deflection, those initially-parallel rays eventually cross, about a half lightyear away, and so an observer at that point could see both of them (hence, seeing half the surface of the Earth).

I don’t believe that Google Earth takes this into account.

[Richard_Pearse]

@Chessic_Sense

Then I don’t understand what you mean by “change your bearing”. You mean something like “make a left turn”? Because that’s not how it works. The ‘curved’ path is a straight line. There’s no turning involved in following a great circle route.

Other than the equator and north/south tracks, all great circles have a constantly changing heading reference true north. If you maintain the same heading reference true north then you end up with a rhumb line, and they are not the shortest route.

[JpnDude]

I’ve flown the NRT (Tokyo-Narita International) to LAX (Los Angeles International) route many times through the years.

In my experience, the average trip going EAST to LAX takes 8-9 hours, while the WEST trip to NRT takes 11-12 hours.

Planes have usually flown a more southern route heading EAST and more northern route (up towards the Aleutian Islands) going WEST.

[robinson]

The jet stream can make a big difference. BTW do you get to NRT the day before you depart (crossing the dateline)? What could be quicker?

[Giles]

@robinson

The jet stream can make a big difference. BTW do you get to NRT the day before you depart (crossing the dateline)? What could be quicker?

It could only be the other way round: California is 17 hours behind Japan, so if you take 9 hours for the trip, you arrive at LAX 8 hours before you left Tokyo.

[TriPolar]

@Giles

It could only be the other way round: California is 17 hours behind Japan, so if you take 9 hours for the trip, you arrive at LAX 8 hours before you left Tokyo.

Bartender: We don’t serve faster than light neutrinos in this establishment.

[Ambivalid]

Flat-Earthers are still out there you know. Sparse as their population might be these days, they do still exist. Perhaps the OP is one such person and his “question” is merely his vessel to show the innate flaws and ultimate falsehood of the notion of a rounded planet. Sort of like those Creationists who come here and pose questions like, “If were evolved from monkeys then why are monkeys still alive?” This OP did just join SDMB with this thread.

[TriPolar]

@Ambivalid

Flat-Earthers are still out there you know. Sparse as their population might be these days, they do still exist. Perhaps the OP is one such person and his “question” is merely his vessel to show the innate flaws and ultimate falsehood of the notion of a rounded planet. Sort of like those Creationists who come here and pose questions like, “If were evolved from monkeys then why are monkeys still alive?” This OP did just join SDMB with this thread.

That’s kind of an uncharitable view isn’t it? The OP seems to understand that the world is not flat, and I think confused by the great circle route. Also, I suspect the OP is very young.

[Ambivalid]

@TriPolar

That’s kind of an uncharitable view isn’t it? The OP seems to understand that the world is not flat, and I think confused by the great circle route. Also, I suspect the OP is very young.

Yes, and admittedly also pretty unlikely. Seeing as how this thread has been going on for nearly three pages now with nothing but speculation as to what the OP does/doesn’t mean, I thought I’d offer that possibility.

[brittekland]

Ummm… it is still page #1 for moi.

Kinda sorta in the same theme as whether it is page 3 to you or page 1, say if Earth is flat, where are the edges exactly and who decides it? Do we got to vote on it?

[brittekland]

For example, how Australians want the world to be viewed: this map.

[Eyebrows_0f_Doom]

@brittekland

Ummm… it is still page #1 for moi.

Not this again. The default page view is 50 posts per page. That’s what most people have it set on.