atpl question!

[boing7777]

Hei, could somebody please help me with a atpl question on navigation? How you do you calcuate it?
Any help would be greatly appreciated!
The great circle distance between position A (59°34.1'N008°08.4'E) and B
(30°25.9'N 171°51.6'W) is:

A:10800nm
B:5400nm
C:10800km
D:2700nm

[citation89]

If you look at the longitudes of A and B, you can see that the longitude of B is the anti-meridian of that of A. Therefore, the great circle track between them will be accross the nearest pole. You therefore need to work out the distance from A to the pole, and then from the Pole to B.

We know 1 degree of latitude = 60nm

A > pole = 90-59°34.1' = 30°25.9' = 1826nm

pole > B = 90-30°25.9' = 59°34.1' = 3574nm

Therefore, total distance = 5400nm (B)

C89

[Flintstone]

What he said but using Calculate distance and bearing between two Latitude/Longitude points using Haversine formula in JavaScript (http://www.movable-type.co.uk/scripts/latlong.html) and CalculateMe.com - Convert Kilometers to Nautical Miles (http://www.calculateme.com/Length/Kilometers/ToNauticalMiles.htm)

Here to help :E

[Nearly There]

Its been a while! but here we go,

Draw the picture, a polar stereographic picture of the northern hemisphere, looking at your 2 points A and B you are going straight over the top.

1 deg of lat = 60 nm

So your calculation is simply a total change in Latitude x 60


Total change in latitude is

90-59°34.1' = 30°25.9'
90-30°25.9' = 59°34.1'

add them together and x by 60 = 90x60=5400nm

[boing7777]

Thank you very much, guys! You`ve been of great help!:8

[G SXTY]

And remember that once you've passed the exam, you'll never, ever, ever have to do that sort of calculation again.

Possibly the most useless of all ATPL subjects - and that's up against some pretty stiff competition. :ugh:

[paco]

A small tip is to add up the longitudes - if they make 180 you know you have to go over the Pole. I'm surprised they haven't got 5400 km in there somewhere.

SXTY - I wasn't exactly going over the Pole in a helicopter but I was using such calculations all the time in N Alberta.

phil

[Ben2000]

Hi all, apologies for resurrecting an old question

The solution from Nearly There above was a great help.

BTW, what if we were NOT going straight over the top? Let's say 45°N 20°W to 30°N 20° E?

What would be the simplest way of calculating this without the complex Haversine...

Many thanks!