I would be grateful for an explanation as to the solution of the following. Thank you for any help in advance.
Q: Given: Grivation 6W, Variation 10W, what is the value of convergence?
a) 4E
b) 16W
c) 16E
d) 4W
Alex Whittingham
22nd Aug 2005, 11:46
preliminary definitions:
Variation. The difference between magnetic and true direction. Whichever is larger can be found using the rhyme:
Variation East Magnetic Least, Variation West Magnetic Best
Convergence. The difference between True Direction and Grid (gyro) direction. Whichever is larger can be found using the rhyme:
Convergence East True Track Least, Convergence West True Track Best
Grivation. The algebraic sum of variation and convergence. Applied using:
Grivation West Magnetic best, Grivation East Magnetic Least
So convergence must be Grivation - Variation = 6W - 10W = - (4W) = 4E
(last time I heard of grivation being used was on RAF VC10s in the 1980s)