Founder,
Firstly, because your wind answer is in degrees true, you need to convert your magnetic track and magnetic heading into true true track and true heading. Variation West, Magnetic Best (i.e. greater than true) therefore you have to take 5 degrees from both 315 and 301 to give 310 degrees true track and 296 degrees true heading.
Next get your CRP-5 out and, using the high speed side, put the centre circle over 225 (TAS), and put the true heading of 296 degrees under the heading index at the very top. Now draw a vertical line DOWN from the centre circle as far as you can. This vertical line represents the true HDG/TAS vector.
You can then see that 310 degrees is 14 degrees to the right of 296 degrees i.e. you have a starboard drift of 14 degrees. Next put your windmark (i.e. a cross) where the 14 degrees starboard line crosses the 250 knots groundspeed line. Draw a line joining the centre circle to this windmark - this line represents the wind vector. As the wind always blows from the centre circle TO the windmark, you can see that the wind is coming from about 190 degrees and that the wind strength is 50- 70 knots in strength.
The last line to draw requires a little bit of imagination. Moving down from the centre circle, try to imagine roughly where the zero speed would be, then draw a line from the windmark to this position. Obviously the line can only go as far as the 150 knot line, but this will suffice. The line you have just drawn represents the true track/Groundspeed line.
Going back to the 50-70 knot windspeed mentioned above - we need greater accuracy than this. We obtain greater accuracy in measuring both the windspeed and direction by rotating the CRP-5 clockwise, to bring the windmark directly underneath the centre circle i.e. the 6 o'clock position. Looking now at the 12 o'clock position, we can read off accurately the wind direction - in this case, 189 degrees. Reading the windspeed from the centre circle to the windmark gives a figure of 63 knots.
189/63, so I would say the closest answer is D.
Hope this helps
VC10 Rib22
