A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Pike
Date: 2021 Dec 28, 14:31 -0800
My Christmas teaser was simply to draw attention to the fact that if you’re not particular about terrain you can use some Northern Hemisphere charts in the Southern Hemisphere upside down and with the lat & long suitably renumbered. However, it turned into a comparison of great Circles versus rhumb lines.
You said your maths knowledge is up to it. You’re lucky; my retention of spherical geometry is about 30 minutes and ellipsoidal geometry 30 seconds. I need to refresh myself every time. I never was able to understand 3D vectors although I’m still hot on 2D.
The Darwin to Buenos Aires flight was a long way (7900nm) and approaching max range for a 787-9. They probably had to balance passengers against fuel. One wonders why they didn’t start from South Australia, which would have been shorter. Perhaps it was something to do with the NT in QUANTAS. I think the journos were a bit ambitious saying the passengers would see the South Pole using the GC route. My rubber band says they were unlikely to go closer than 80S. However, ch Lats suggest it would only be another 50 nm to fly down the 58W meridian to the South Pole and up the 131E meridian to Darwin. Adelaide would be a useful fuel diversion.
Darwin to London via the North Pole sounds rather impractical unless you were aiming at a particularly wealthy set of passengers. Flying up the 131E meridian and down the Greenwich Meridian would be 8486nm compared the great circle route of 7494nm. I don’t know what max range QUANTAS believe they can squeeze out of their 787s DaveP