The video that you are watching shows how to find the TMG (Track Made Good), whereas Page 13 exercises need you to calculate the heading and ground speed. Look for "Flight Planning with Forecast winds" in the CR3 manual, or flight planing videos

Thank you Wayne ... it makes sense now.

I am still struggling to get the same answer as the workbook e.g.
Full Flight Planning, page 15, No 5

Question:
Flight Planned Track (FPT degrees True): 186
Mag Variation: 13 degrees E
Forecast Wind (degrees T/kt): 274/20
TAS (kt): 100

Find:
Heading (T)
Heading (M)
Ground Speed
ETI (mins) for Distance (nm): 168nm

I get a True Heading of 197 degrees (using the 11 degrees crab angle) - the work book has 198 which I assume is because the 12 degrees angle was used - Do I use the closest one or the highest one?

For ground speed I get 93kt calculated as 98 kt effective speed (using 11/12 degrees) less 5 kt headwind - the workbook has 97 kt

Will you please document all the steps using the CR-3 here so that I can see where I went wrong?

Thank you

It would help those of us who don't have the workbook to hand were you to post the question details ?

Hi John,

Updated

[color=blue]I get a True Heading of 197 degrees (using the 11 degrees crab angle) - the work book has 198 which I assume is because the 12 degrees angle was used - Do I use the closest one or the highest one?
[/color]
If the figure is midway, pick the integer number which appeals to you. Otherwise, just round off to the closer. It really doesn't matter all that much as the pragmatic accuracy required is less than that level of discrimination. In this case, 197/198 are both fine
.
[color=blue]For ground speed I get 93kt calculated as 98 kt effective speed (using 11/12 degrees) less 5 kt headwind - the workbook has 97 kt[/color]

ETAS is around 98 so that is fine. However, the 5 kt H/W looks to be a bit suss. Perhaps you can rework that bit ? My figuring shows it to be a little less, maybe 1-2 kt ? Again, using these analogue devices, you are not going to get superlative precision.

Thanks John,

Now I am worried that my CR-3 is broken because I still get a 4/5kt headwind ...

[attachment=2551]CR3.png[/attachment]

Understand that the device will not give me 100% accuracy, but given that the exam has a very small margin for error, I am concerned that I will get it wrong if I cannot work out how to get it more accurate

When it comes to the wind calculations the E6B is more accurate than the CR computers. CASA has this worked out and uses the E6b for Commercial and have to use the Cr computers for the ATPL. There will always be a slight difference, in the real world most of cant fly to a 1 knot difference.

[color=blue]Now I am worried that my CR-3 is broken[/color]

There doesn't look to be anything terribly wrong with your device.

However, you have now isolated your errors for our comments. That is what we needed - to be able to see the problems on the device and provide a suitable story for you.

I note, on the scanned image of the device that you have positioned the

(a) TAS marker (ie the "10" marker on the original inner C/D scale before the scale was reworked to give the angles for sine/cosine values) is a bit off the TAS value. Pretty trivial but you do need to try to position things as accurately as you reasonably can manage to minimise calculation errors. The general scale accuracy on some of these clones is not all that impressive so we need to exercise what diligent care we can during calculation work. The reason why we need this set accurately is that it sets the scales for both the sine (drift) and cosine (ETAS) multiplications. Those sums need to be accurate if you want to end up with a reasonably good answer,

(b) and you have set 197 against TC. Why ? I know what you have done but not why, specifically. Once I know what your specific reasoning processes were, we can go through why that is not the correct number - that is, I need you to walk me through your logic process for the setting so I can give you a logical contrary story for reflection. Once we do that, and you have some time to reflect upon the story, you will have the process squared away. I have to note that I think the Jepp user guide is dreadfully convoluted and difficult to follow. It all can be explained in a far easier to understand manner.

Thanks John,

The slightly misaligned TAS is noted and agreed on the manual ... it is not great to say the least.

When you say "clones" is there a better device to get?

My logic is simply that I started with placing the 186 heading T (given) on TC and then added 11 degrees based on the 11 degrees crab angle obtained (19 kt right cross wind) which is 186 + 11 = 197 degrees T

Thanks for your help

[color=blue]When you say "clones" is there a better device to get?[/color]

First, does yours have a problem ? On the calc side, line up the outer scales (C/D scales) so that 10 is against 10. Read around. All the various numbers should be aligned similarly. Then set, say 10 against 20. Read around. All the various numbers should be aligned in the ratio 2:1, so 10 is against 20, 20 is against 40 and so on. The extent to which there is misalignment indicates the extent of any manufacturing problems. The same needs to be done with the look up table cutouts but that gets a bit involved. Similarly, on the nav side one can set the TAS symbol against the 10 (this is the same as 10 against 10 on the other side) and check a few sine and cosine values around the scales. Probably a bit involved for most. Unless the misalignment is significant, probably all is OK as we are looking at the device being reasonably fit for purpose rather than being an accurate slide rule such as we had in previous years at a greater cost of ownership.

[color=blue]My logic is simply that I started with placing the 186 heading T (given) on TC and then added 11 degrees based on the 11 degrees crab angle obtained (19 kt right cross wind) which is 186 + 11 = 197 degrees T[/color]

Was not the 186 value your track, rather than heading ? What does the TC stand for ? What is the significance of your 197 ? Perhaps have a quick revisit of the calculations ?

Thanks I will check my device for accuracy

186 is the track yes - apologies used the wrong term
TC - True Course on the CR-3 wind side
197 is the TC after adjustment by the 11 degrees crab angle

So in more detail ...

For Magnetic course
1. Place the 186 degrees True FPT (given) on TC on the green disk
2. Read cross-wind component of 19 kt right at 274 degrees True
3. Find 19 on the outer scale of the computer and read 11 degrees crab angle below it
4. Adjust the inside scale from 186 degrees by 11 degrees by moving the disk left until 197 degrees is on TC
5. Now adjust by the Magnetic variation by deducting 13 degrees to get final answer

For speed
1. As the crab angle is 11 degrees, find 11 degrees on the effective TAS scale and read a TAS of 98 kt
2. Deduct the headwind component (5 in my case) from the effective TAS to get 93 kt

[color=blue]186 is the track yes - apologies used the wrong term[/color]

All OK.

[color=blue]TC - True Course[/color]

That's US-speak for our "track"

[color=blue]197 is the TC after adjustment by the 11 degrees crab angle[/color]

Not quite. 197 is track corrected for drift to end up with heading.

[color=blue]adjust the inside scale from 186 degrees by 11 degrees by moving the disk left until 197 degrees is on TC[/color]

No. TC has naught to do with headings, it is [color=red]track[/color]. You leave 186 against TC and note the heading somewhere else for the direction in which you need to point the aircraft. When you put 186 back against TC, what does your W/C become ?

One needs to keep in mind that the CR does its calculations along the TR/GS vector which is why folks get all confused by ETAS and why ETAS has nothing at all to do with the Dalton's solution, despite widespread common belief to the contrary. When you read, or someone tries to tell you that the Dalton somehow attends to ETAS in the background (or some similar nonsense), just smile sweetly and knowingly while shaking your head.