PPL studies NAVIGATION. Dead Mental Reckoning, Clock Code!

[Driver170 42]

I have just learn't the MDR chapter of navigation and i thought i grasped the basics, but i was wrong! Once i got the mock questions at the end i didn't have a clue. It seems i'm lost with the clock code method.

 

Here the question and answers...

 

You plan to fly a cross country flight at 2,000 feet at a true airspeed of 120 knots. Your track is 270* (TRUE) and the wind is from 225* (TRUE) at 24 knots using the mental dead reckoning clock code, what true heading would you steer and what would be your magnetic heading if the local magnetic variaton is 4* west?

 

A. 258 TRUE 262 MAGNETIC

B. 261 TRUE 265 MAGNETIC

C. 261 TRUE 257 MAGNETIC

D. 279 TRUE 283 MAGNETIC

 

The answer is B

 

I can work out the drift angle 60 / 120 true AS = 0.5 X 24 knots wind = 12

 

Now this is where i get confused when applying it to the clock code? Can someone help please!

[Hippo 34]

I'll have a go...

 

270 - 225 = 45 degrees difference

 

Clock code as I understand it

 

15 minutes past the hour (3 o'clock position) -> 1/4 of the clock

30 minutes past the hour (6 o'clock position) -> 1/2 of the clock

45 minutes past the hour (9 o'clock position) -> 3/4 of the clock

60 minutes (12 o'clock position) -> ALL of the clock

 

As the difference between the track and heading is 45 degrees, you multiply the max drift (12 as you've calculated) by 3/4 = 9 degrees which is the drift you require to get the answer.

 

variation west -> magnetic best so add 4 degrees to get magnetic heading.

 

Hope that helps.

 

 

[Driver170 42]

Right think i have got it, check out Q 4, 5 ?

 

Do you always have to takeaway track heading away from wind heading?

In the book it never mentioned that?

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[Driver170 42]

https://www.dropbox.com/s/mkm5nzxw0q30ln3/Photo%2014-02-2015%2012%2022%2038.jpg?dl=0

[Driver170 42]

Need help on 5 its a little tricky!