Hi!

 

I am looking for instructions as how to calculate counter-radials when flying VOR's.

 

any tips how I can do this quickly and easy:)

Reciprocals? I add 200 and subtract 20 - or if that gives me a number greater than 360 I subtract 200 and add 20. Alternately look at your directional gyro while on course and read the number at the bottom of the dial.

 

Jim

Yea thats what its called:-p

 

Thanks a lot, that is exactly what im looking for!

Just a thought...

 

So if the radial is 245 the reciprocal is 245 -200 = 45 + 20 =65 right?

 

BUT what if the radial is 175...

if I add 200 then the value is above 360 (375) and if I remove 200 its below zero.

So whats the method then?

Well I guess in that situation 175+200=375, then 375-20=355 so it's less than 360. I just do it this way because it's easier to do in my head than 175+180=355. :smile:

175 is 5 degrees before 180 so the reciprocal is 355: 5 degrees before 360.

 

Simples

Yeah I know Ailchim, I just tried to make sure that the calculations worked.-p

 

Thanks for the clearification though:)

hihi! Being 75, when I was at school, we had no calculators, and we had a lot of mental calculation exercises to do.  So, for me adding 180 to 123 or substracting 180 from 199 is no brainer. And being fluent in mental calculation is also of a great help when doing circuits, adding 90 degrees for right-hand circuits and substracting 90 degrees for left-hand  circuits.

 

Jean-Jacques

I use +200 - 20 method, but reduced to digits, so it becomes +2 -2:

 

 

So for example angle 2 5 0: I cannot add 2 to first digit so I subtract 2 from the first digit. Then I add 2 to second digit. 2-2=0 5+2=7 so it would be 0 7 0

 

Second example 1 2 0: First add 2 to the first digit and then subtract 2 from the second digit. 1+2=3 2-2=0 so it becomes 3 0 0

 

There are problems if the second number is 0, 1 or 9 because it then it could affect the first number, but that's why we have a brain.

 

The quickest way is to look at your gyro compass or nav compass.

 

@Jayjay: I believe most of us can do quick math when sit in home, but when you sit in aircraft, it's much different.

That's confusing. Just think of runway pairs.

 

Ry 9/27

3/21

18/36

5/23

 

For single digits just add or subtract the few degrees.

The ones I have problems with are like Rwy hdg 026, left pattern, what is the heading of the first crosswind leg?

 

I guess I'd do reciprocal first then add 100 and subtract 10: (((26+200)-20)+100)-10=296.

 

You're right g_precentralis, that's why those vertical card DGs have marks every 45° :smile:

 

 

The ones I have problems with are like Rwy hdg 026, left pattern, what is the heading of the first crosswind leg?

 

Just use 90 degree mark on DG before turn. :smile:

Yeah that works fine - until you fly something with one of these:

 

 

...or even worse, one of these:

 

Jim, that one is easy, just add 270 (180+90) to your Rwy hdg 26 degrees and voilà! 296!

 

Jean-Jacques

Haha, true, there is no rule that can be applied in every situation :smile: .

:rolleyes:

Yeah that works fine - until you fly something with one of these:

 

...or even worse, one of these:

 

 

Yesss! and that's where our brain can help our old squinting eyes  :rolleyes:

 

Jean-Jacques