Does anyone know why the answer is 200 degrees magnetic. I am aware it states heading of 195 degrees magnetic. But if you measure it on the map, its closer to 195 degrees true. When I run through everything the calc's I come up with approx 185 degrees magnetic as the correct answer. If you even measure of the map from Jomara to Walgett you get ~195 degrees True, or 185 degrees magnetic. Is the answer actually wrong??


""
You are flying from ST GEORGE (YSGE) (S28 03 E148 35.7) to WALGETT (YWLG) (S30 02 E148 07.5).

After departure from YSGE at 0011 UTC, you are forced to divert to the left of the flight planned track to avoid smoke from bush fires. At time 0018 you are over Shirley homestead, 5 nm to the left of track. You decide to take up the flight planned heading of 195 degrees M. At 0039 you fix your position as being over Jomara homestead and still 5 nm left of track.

The heading you should fly to track direct from Jomara homestead to YWLG is closest to -
Select one:
210 degrees M
185 degrees M
190 degrees M
200 degrees M
""

You have been flying a heading of 195ºM and have been paralleling track at 5 nm left. So any heading change to regain track will be to the right. So any answer less than 195 is incorrect, which eliminates 2 answers. It then becomes a simple "1 in 60" calculation to determine the closing angle. From Jomara to YWLG is 60 kms, measured from the WAC chart. 5nm left with 60 to go, makes a closing angle of 5º. So a heading change of 5º to the right is required, so new heading required is 200ºM

Thanks Wayne. I understand how to get the answer if I follow the 'written' in the question. But draw a line from Jomara and Walgett and place your navigational protractor on it and measure it. The angle is ~195 degrees True, or ~185 degrees magnetic if you account for variation.

"But draw a line from Jomara and Walgett and place your navigational protractor on it and measure it. The angle is ~195 degrees True"

This 195 degrees or whatever you measured (you dont need to measure this at all) is not your HEADING, it is your TRACK TO INTERCEPT(TTI) direction. Your TRACK and your HEADING are different things! The question asks about your HEADING, not your TRACK, even if it asks about your TRACK, you don't need to measure it, use your 1 in 60.

The difference between your TRACK and HEADING is due to DRIFT, which I believe is very well explained in the PPL book.

To work out your new heading, use your orginal heading, add the angle from your 1 in 60 answer, you get your new heading.

That makes more sense, cheers wsxmfy

I treated that question as being clam (i.e. no drift), as there was no mention of wind present. That question should be updated to include mention of "... there is a easterly wind, as such the pilot takes on the heading of a 195 degrees magnet between Walgett and Jomara....".

IMHO the update you mentioned is not necessary and may not even be true, if the question doesn't mention wind, you make no assumption about wind. All you need is 1) FPT, 2) your original heading, and 3) your fixed positions after certain times to work out everything else, including TE, CA, TTI, drift, wind etc.

In fact, the drift, wind, GS etc. you worked out are based on an assumption that the wind is constant and you moved along a straight line between the two fixed points (that is exactly what you did, isn't it, you use your ruler to connect the two point with a straight line). This assumption is not necessary true, you could be zig-zagging between the two points when winds are variable. All you actually know for cetain (the measurement you took) is that you kept a constant heading, at time X you are at A and at time Y you are at B. The drift and wind are just an average estimation.

The above 1),2) and 3) are also the only infomation you know in a dead reckoning situation in real life (without the help of other navigation equipment of course). You don't always know the wind direction in real life, even if you do, the wind direction may change. That's the whole point of all these exercises, work out your situation with the infomation at hand.


I don't think you will ever be told the direction of wind in these 1 in 60 questions, just like in a question that provides you TAS 100kts and head wind 10kts, the examiner will never tell you GS is 90kts, you should know it yourself.