Refer to figure.

For a Lambert chart the following convergency formula is applied: **Convergency = Change of Longitude x Sin Parallel of Origin.**

Average true track 080^{o} is the track measured exactly in the middle point between X and Y, while crossing the 35^{o}W meridian.

Parallel of origin is the mean latitude between the two standard parallels: *(75 ^{o} N + 30^{o} N) / 2 = 52.5^{o} N.*

Applying the rule, **" SAME HEMISPHERES - SUBTRACT"**, the Change of Longitude between X and Y is:

*40*. Thus,

^{o}W - 30^{o}W =**10**^{o}*Convergency = 10*.

^{o}x sin 52,5^{o}=**7.9**^{o}That means that the true track from X to Y position changes by 7.9^{o}, so until the middle point, it changes by: *7.9 ^{o}/2 = 4^{o} rounded*.

Bear in mind that both X and Y lie on the **Northern hemisphere**, where meridians converge inwards towards the North Pole and as we travel eastwards and at a higher latitude, the true track increases. So, true track will be lower at X than in the middle point and consequently lower in the middle point than at Y.

*The direction at position X is: 080*^{o}- 4^{o}= 76^{o}and*The direction at position Y is: 080*^{o}+ 4^{o}= 84^{o}.

**the direction of the straight line at position**

__X is 076__º.Your Notes (not visible to others)

This question has appeared on the real examination, you can find the related countries below.