aloges
Posts: 14842
Joined: Tue Jan 17, 2006 3:38 am

The Great Circle Challenge

Fri Apr 30, 2004 7:05 am

So I'm a bit bored...

Just recently, I asked myself which would be the longest great circle that could be entered into the Great Circle Mapper.

The longest I have come up with is AKL-GIB at 10749 (nautical) miles, any takers? Big grin
Don't cry because it's over, smile because it happened.
 
ScottishLaddie
Posts: 2309
Joined: Sat Jan 03, 2004 8:30 am

RE: The Great Circle Challenge

Fri Apr 30, 2004 7:11 am

LCA-PPT 11221 miles  Big grin
 
aloges
Posts: 14842
Joined: Tue Jan 17, 2006 3:38 am

RE: The Great Circle Challenge

Fri Apr 30, 2004 7:19 am

Not to rain on your parade, but try switching to nautical miles ("Path Distance" dropdown)!  Big grin
Don't cry because it's over, smile because it happened.
 
ScottishLaddie
Posts: 2309
Joined: Sat Jan 03, 2004 8:30 am

RE: The Great Circle Challenge

Fri Apr 30, 2004 7:21 am

Grrr Big grin  Big grin

Filler
 
redngold
Posts: 6673
Joined: Wed Mar 22, 2000 12:26 pm

RE: The Great Circle Challenge

Fri Apr 30, 2004 8:02 am

Isn't SIN-UIO the longest possible? I think I read somewhere that Singapore and Quito, Ecuador, are exactly opposite (polar opposites) nearest to the equator... which would be the longest possible great circle.

SIN-UIO, 10649 nm

AKL-GIB doesn't look right... If you plug in GIB-AKL, although it shows 10749 nm, I think that is an error. I did a straight-line great circle mapping on a globe, and it doesn't even go near Antarctica.

Here's the great circle line I ended up with AKL-GIB (roughly):

AKL
Cook Islands (N.Z. territory)
Guadalajara, Mexico
east of Mobile, Alabama, US
Cape Hatteras, North Carolina, US
north of Terceira, Azores (Portugal territory)
Gibraltar
Up, up and away!
 
ben
Posts: 1369
Joined: Fri Aug 06, 1999 9:27 pm

RE: The Great Circle Challenge

Fri Apr 30, 2004 8:14 am

The longest possible great circle on the earth is 10,800 nautical miles... so you're pretty close to that limit.

Each minute of latitude is one nautical mile. There are 60 minutes in a degree, and 180 degrees in half of the earth by following a great circle. That = 10,800 nm.
 
redngold
Posts: 6673
Joined: Wed Mar 22, 2000 12:26 pm

RE: The Great Circle Challenge

Fri Apr 30, 2004 8:17 am

Yes, I understand that 10,800 nm is the limit; but the great circle plotting of AKL-GIB over Antarctica just doesn't make sense!

Take a look at the plot of AKL-MAD... It's much more what I'd expect for AKL-GIB -- going north, then west, and finally south. AKL-GIB should be almost due northeast for the entire trip.

[Edited 2004-04-30 01:21:50]
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TFJamie
Posts: 117
Joined: Thu Mar 04, 2004 6:16 pm

RE: The Great Circle Challenge

Fri Apr 30, 2004 8:19 am

if you look at the coordinates AKL-GIB are around 7 minutes from being 180 degrees apart in the E-W direction and the difference in the S-N coords is 51 minutes

In UIO-SIN the difference in S-N coords is 1 degree and 13 minutes and 2.5 degrees from being 180 degrees apart in the E-W direction, so the distance should be less

A flaw in this is the difference in the size of longitudes, but polar opposites have the same S-N coords and are 180 deg. apart in the E-W direction.

On a side note:
AKL-OZP is 10786nm
 
redngold
Posts: 6673
Joined: Wed Mar 22, 2000 12:26 pm

RE: The Great Circle Challenge

Fri Apr 30, 2004 8:32 am

AKL-GRZ is 10743 nm, and also has a route much more like what I would approximate for AKL-GIB.

AKL-GIB the other way, by my estimate:

AKL
SYD
just south of MLB
northern edge of the Maldives
ashore on Africa east northeast of Salalah, Oman
just north of Medina, Saudia Arabia
just south of Alexandria, Egypt
just south of Sfax, Tunisia
GIB

[Edited 2004-04-30 01:33:16]
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Olympus69
Posts: 1571
Joined: Sat Jun 15, 2002 11:21 pm

RE: The Great Circle Challenge

Fri Apr 30, 2004 9:38 am

AKL and GIB are so close to being 180 degrees of longitude apart that the position of the airports in relation to the cities (for Auckland anyway) could affect which direction is shorter.
 
USAFHummer
Posts: 10261
Joined: Thu May 18, 2000 12:22 pm

RE: The Great Circle Challenge

Fri Apr 30, 2004 9:50 am

La Coruna, Spain (LCG) - Christchurch, New Zealand (CHC) : 10769 nm  Smile

http://gc.kls2.com/cgi-bin/gc?PATH=LCG-CHC%0D%0A&RANGE=&PATH-COLOR=red&PATH-UNITS=nm&SPEED-GROUND=&SPEED-UNITS=kts&RANGE-STYLE=best&RANGE-COLOR=navy&MAP-STYLE=

Greg
Chief A.net college football stadium self-pic guru
 
sq452
Posts: 994
Joined: Sat Apr 17, 2004 4:49 am

RE: The Great Circle Challenge

Fri Apr 30, 2004 9:57 am

PPT-JNB

10,365 nm

if you want to see a weird one on the map (makes an L'ish look on GCM) try JNB-ANC....funky!
SIN > CVG > BOS
 
bohica
Posts: 2308
Joined: Tue Feb 10, 2004 3:21 pm

RE: The Great Circle Challenge

Fri Apr 30, 2004 10:00 am

I got it!!!

HNL-GNZ (Ghanzi Botswana) 10,774 nm. Big grin

From the Great Circle Mapper:

From To Distance
HNL (21°19'07"N 157°55'21"W) GNZ (21°41'S 21°39'E) 10774 nm





 
redngold
Posts: 6673
Joined: Wed Mar 22, 2000 12:26 pm

RE: The Great Circle Challenge

Fri Apr 30, 2004 10:25 am

USAFHummer:
That's a great one! It's much more like what I would have expected from AKL-GIB... the smooth double curve.

SQ452:
That's the same error that was coming up with AKL-GIB.
Up, up and away!
 
Blackbird1331
Posts: 1740
Joined: Wed Apr 14, 2004 10:47 am

RE: The Great Circle Challenge

Fri Apr 30, 2004 10:38 am

Call me dizzy. Glad it's time for bed.
Cameras shoot pictures. Guns shoot people. They have the guns.
 
sq452
Posts: 994
Joined: Sat Apr 17, 2004 4:49 am

RE: The Great Circle Challenge

Fri Apr 30, 2004 10:40 am

oh, yah it seemed a bit odd Redngold that it would do that.

Still, I love the Great Circle Mapper
SIN > CVG > BOS
 
TFJamie
Posts: 117
Joined: Thu Mar 04, 2004 6:16 pm

RE: The Great Circle Challenge

Fri Apr 30, 2004 11:23 am

Like said before 10786 is the unbeaten record of AKL-OZP (Moron, Spain).

Isn't it always shortest over the poles if the places are polar opposites, and in fact that any direction would come out the same if flown in a straight line (Look at the poles themselves, any direction you go from them, and you will end up at the other one).

 
timz
Posts: 6114
Joined: Fri Sep 17, 1999 7:43 am

RE: The Great Circle Challenge

Sat May 01, 2004 1:32 am

Maximum possible distance is 10801.26 nm on the WGS84 spheroid. Auckland to Moron does indeed look like 10786.26 nm; initial course from Auckland would be 326.3 degrees true.

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