Length of a nautical mile and compass swirl
(This is also posted on the OATS forum)
. .I just can't figure these two out:
OATS GNAV 061 page 1-20:
The length of a nautical mile is longest at the poles, and shortest at equator, because the Earth being oblate spheroid. I just can't see why it isn't OPPOSITE ! Someone please enligthen me. I figure that the same angle from the center of the Earth to either the pole or the equator must mean that the distance covered should be related to the radius of the earth. Since the equator is further away than the pole, why isn't the nautical mile then LONGER at EQUATOR ?
. .OATS INS 022 page 9-15 and 9-16
I am not happy with the use of "turning through north/south". It is confusing, because how does liquid swirl exactly behave ? Let me give a questions to claify the problem:
On the Northern hemisphere, consider two scenarios:
1) Turning from 345 to 355 degrees
2) Turning from 005 to 015 degrees
Answers:
a) Liquid swirl will increase turning error in both 1) and 2)
b) Liquid swirl will increase turning error in 1) and decrease turning error in 2)
c) Liquid swirl will decrease turning error in 1) and increase turning error in 2)
d) Liquid swirl will decrease turning error in both 1) and 2)
. .I say a) is correct, others say b) is correct. With the phase "turning through north", what is meant ? Because in scenario 2) we are actually "turning south", but we are neither turning through North nor South.
Which one is correct, and why ?
. .LGB