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Find the Actual Wind in Flight on a CR 5 (2 or 3)

Bungee

Topic Author

Bungee created the topic: Find the Actual Wind in Flight on a CR 5 (2 or 3)

Hi everyone

I had some troubles getting working out the winds in flight (exercises N 18 on Page 4.47)

In the book the examples are with an E6b with the wind slider. I am using the Jeppesen CR 5 and when I practiced the examples in the Jeppesen book it all worked out fine, when I tried to apply the same logic to the 2 questions on page 4.47 of the CPL NAV book, I struggled to get the answer, even when I plotted the answer on my CR 5, I still could not seem to get it to make any sense. I think a lot of my issues was the different in terminology, the Jeppesen just works a little differently and thought it may be good to share my learnings.

Here is my workings on the CR 5 (CR 2 and CR 3 would be the same)

First thing to note is that TMG is the same as True Course, and True Heading is the same as Heading Magnetic.

Question 1

TMG is 112 degrees
HDG is 122 degrees, this is 10 degrees of drift (L) so Wind is from the RIGHT
TAS is 165kt (effective TAS of 163kts)
Ground speed is 150kts

Knowing all of this info, go to the wind side of the CR 5 and place the TMG of 112 degrees on the TRUE COURSE index

Headwind is 13kts so draw a line to the right (drift was left so wind must be from right) from 13 above the centre of the CR 5 (Headwind)

Make sure TAS index is on effective TAS of 163kts and find 10 degrees (drift) on the inner circle and it will match up with 29 on the outer circle (29kts of Xwind)

Draw a line up from 29 kts to intersect with the earlier line from the 13kts of headwind.

You will get the answer of 178/32kts

Now lets try the same with Question 2

TMG is 086 degrees
HDG is 082 so I have 4 degrees right drift (wind from the left)
TAS is 178
GS is 158 (20 kts HW)

Place TMG of 086 on the TC index

Draw a line from 20 kts headwind to the left (we had right drift so wind must be from the left)

Make sure TAS index is on 178, Then find 4 degrees on the inner circle and it tells me I have 12.5kts of Xwind on the outer circle

Draw the lines to intersect and to get 055/23kts

As a side note, it helped me to right this post as I was working it out... (sort of like some of Bob's flowcharts) and a quick pencil drawing was also valuable.