How are you supposed to get the East/West variation on this question in the FAA PPL written exam?

Question

While taking a practice test, I needed to calculate the magnetic heading between two airports. Most of the time I run into a problem, the map will provide me with isogonic lines with the East/West variation visible. But in at least one or more questions, the isogonic line is either not shown, or the numbers are not visible.

Using the protractor to calculate the angle on the isogonic line using the latitude/longitude lines doesn't seem to give me the correct number either.

Does anyone know what I am doing wrong or how I can come to a correct answer?

Problem

(Refer to figure 23.) What is the estimated time en route for a flight from Claxton-Evans County Airport (area 2) to Hampton Varnville Airport (area 1)? The wind is from 290° at 18 knots and the true airspeed is 85 knots. Add 2 minutes for climb-out.

Valid Answers:

1. 44
2. 39
3. 35

Update: I added an actual sample problem. Assuming the only information I am able to work with is the map, the question and my E6B (manual or electronic).

Update I found the original question that got this thread started:

(Refer to figure 24.) Determine the magnetic heading for a flight from Allendale County Airport (area 1) to Claxton-Evans County Airport (area 2). The wing is from 090° at 16 knots, and the true airspeed is 90 knots.

The correct answer: 209°

The solution given in study mode: With a plotter, measure the true course from Allendale to Claxton-Evans as 212°. Use a flight computer to find the true heading of 203°. Add variation of 6°W. 203°+6°=209°.

Answer 1

Real answer: The FAA screwed up in preparation of that exam question (this sometimes happens; they aren't perfect) and cropped the sectional to where the isogonal lines and or isogonal values are not visible. As it happens I know that area of the country pretty well.

It works out that Claxton has about a 6.5 deg W magnetic variation (get the full VFR sectionals for that area) and Varnville is just shy of 7deg W variation; I'd use 6.75 deg W as your number for mag variation over the duration of the flight. That works out to a course of 051 deg magnetic, 56.5 NM along the route. With winds at 290 at 18 kts cruising at a true airspeed of 85 kts, this gives an aircraft heading of 041 magnetic in cruise with a ground speed of 93 kts.

Now here's the thing: what is your groundspeed during climb out? That's going to also be necessary to calculate how much ground you cover during your 2 min climb to cruise. And critical to answering the question correctly.

Now, IF WE ASSUME a constant groundspeed of 93 kts, from point to point, that gives a flight time of 36.5 minutes. If we further assume the two minutes of climb are not enroute and just maneuvering from takeoff to on course right over the Claxton airport and we descent into Varnville at 93 kts as well, we get a figure of 38.5 minutes total flight time. Therefore, I'd select 'B' as my answer.

As a side note, I landed an LSA out at Varnville only once and that place is virtually abandoned; it was difficult to identify as an airport from the air, the runway is anemic and derelict, there are virtually no buildings there and all I could find for traffic there was a decrepit C-150 rusting in the sun. I took off again - and very glad my engine didn't quit, leaving me stranded there.

Answer 2

The answer is that magnetic variation is not a factor in this problem.

See this answer: When are winds given with respect to true vs. magnetic north?

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Another potential non-real-world issue with this problem might come from this:

NOTE: Chart is not to scale and should not be used for navigation. Use associated scale.

So, use another piece of paper to figure out how far the two airports are, then use your plotter to find the True Heading-- do not use your plotter to measure the distance!

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Here is my solution to your original problem. I'm not going to work out the second one since you already have the solution, and the a real question should include the variation as clearly readable information somewhere, either on the chart or in an AFD entry.

I am using a method that doesn't require writing on the chart, which is not allowed on the FAA tests. In real life, you would draw your course on the map for reference during your flight.

First, find the distance between the two points. Mark it on the edge of one of your blank sheets:

Now measure the distance using your on-maps scale not your plotter

I got 57 nautical miles, from the center of Claxton to the center of Hampton.

Estimate the true bearing from Claxton to Hampton. This is a northeast course, so we know the true course will be around 40-50 degrees.

Now put the Course Arrow on the two airports, and the hole of the plotter on the latitude line:

From your plotter, read off exactly 45 degrees from the third scale. You know to ignore the others because you expect the answer to be near 40 or 50 degrees.

Now pull out the whiz-wheel and follow the directions on it!

1. Set wind direction opposite TRUE INDEX
2. Mark W up from the Grommet (add 18kts)

3. Place true course under TRUE INDEX
4. Slide true airspeed under W (85kts)
5. Read Ground Speed under the Grommet

I get 91.5 kts GS.

Now you have all the information you need to do the calculation:

Remembering that a knot is a nautical mile per hour,

$${ 57nm \over 91.5kts } \times {60\;min \over hr} = 37.4 \; minutes$$

Now add two minutes for climb as directed in the problem, and you get a little over 39 minutes.

Note that you can ignore variation in this problem because both wind and course are calculated as true bearings. Since the problem doesn't ask what the Magnetic Heading or Course Heading are, that information isn't required.