## CFI Brief: Enroute questions using the E6B Flight Computer This week we are going to look at a few questions as they relate to enroute flight, specifically questions that require the use of an E6B. Enroute flight is a popular topic on the FAA knowledge exam and these questions may be very similar to the ones you encounter on your knowledge test. The first question involves determining a magnetic heading using our E6B Flight Computer.

(Refer to Figure 26.) Determine the magnetic heading for a flight from Fort Worth Meacham (area 4) to Denton Muni (area 1). The wind is from 330° at 25 knots, the true airspeed is 110 knots, and the magnetic variation is 7° east.

Let’s break this question down into four simple steps.

1. Plot a course from Meacham to Denton, and determine the course heading using a plotter. I get 021°.
2. Next, using the wind given in the question (330 @ 25) , calculate a correction angle using the E6B. This angle will be the difference between the course bearing and the heading required to maintain that course. I’ve computed a correction angle of 10° to the left.
3. Remember a left correction angle is subtracted from the course to obtain a true heading. 021° (course from step 1) – 010° (wind correction from step 2) = 011° (true heading)
1. Lastly find the magnetic heading by adding or subtracting the variation given in the question (7° east) to the true heading. Remember subtract east and add west. 011 – 7 = 004° (magnetic heading)

How far will an aircraft travel in 2-1/2 minutes with a groundspeed of 98 knots?

To find the distance flown in a given time, multiply ground speed by time. The distance flown in 2-1/2 minutes (convert to hours by dividing by 60) at a ground speed of 98 knots is .04 x 98 = 4.08 NM.

Or…

Using our E6B we would take our rate indicator of 60 on the inner scale and line it up with 98 on the outer scale. The inner scale shows time, so we would locate 25 (2.5 minutes) and on the outer scale read 40.8 interpreting that as 4.08 NM.

This next question requires us to sort of work in a backwards direction to find the correct answer.

If a true heading of 135° results in a ground track of 130° and a true airspeed of 135 knots results in a groundspeed of 140 knots, the wind would be from?

So a 135° means we are flying in a southeast direction and if this true heading is resulting in a ground tack of 130° the wind would have to be coming from somewhere off our right wing pushing the aircraft to the left. In addition, we know that the wind is also resulting in an increase of groundspeed so the wind is somewhere behind us. Using these two key pieces of information we can determine the wind must be from the southwest.

Using the wind side of the E6B we will line our true Index up with our true course of 135° with the grommet located at 135 on the center vertical line to account for the true airspeed. From there we have determined that the wind is coming from southwest so looking between the S and W find on the vertical line the 5° and count vertically down 5 to account for the 5 knot increase in speed. Draw a line from that point back to the grommet and rotate the circle until the line appears under the true index. On the inner circle read your wind direction of 246° and counting up from the grommet to the end of the line your wind speed of 13. Your wind is coming from 246 @ 13 knots.

See, its really not all that hard if you break the questions down into smaller chunks. Try one on your own and leave the answer in the comments section below, I will let you know if the answer is correct.

(Refer to Figure 26.) Determine the magnetic heading for a flight from Dallas Executive (area 3) to Fort Worth Meacham (area 4). The wind is from 030° at 10 knots, the true airspeed is 135 knots, and the magnetic variation is 7° east.

1. Aaron S. Hawley
Posted August 12, 2015 at 7:57 pm | Permalink

Here is a problem from the Complete Private Pilot, page 9-8. The wind direction is 240 and the wind speed is 38 knots. The true course is 115 and the true airspeed is 90 knots. I’m not sure I get the same answer with my ASA E6-B slide flight computer.

I start by sliding the grommet to 90 knots, and put the true index to 240 and put a mark at 128 knots (for the wind nof 38 knots). I rotate so the true course of 115 is under the true index. I then slide up until the wind mark reaches 90. Now the grommet is over 108 knots and there is a wind correction angle of +26 degrees. That means the ground track is 141 at a ground speed of 108 knots.

How’d I do?

2. ASA
Posted August 13, 2015 at 5:49 am | Permalink

Hello Aaron, you appear to be doing all the right and correct steps however your answer is coming out a little off. When I slide the wind velocity mark to true airspeed I read 106 under the grommet. When I look back to my wind velocity mark it sits just left of the 20° vertical line showing about 19°. Adding 19° to 115° TC I get a TH of 134° and Ground speed of 106 knots.

3. Aaron S. Hawley
Posted August 14, 2015 at 7:04 pm | Permalink

I had incorrectly put the wind mark at 138 knots (instead of 128 knots). This added 10 more knots of wind. That is how I got a higher ground speed and a higher wind correction angle.

4. Aaron S. Hawley
Posted August 14, 2015 at 7:29 pm | Permalink

I’ll take a shot at Figure 26.

Plotting the course from Dallas Executive to Ft Worth Meacham I get a true course (TC) of 289°.

With the E6B, I slide the grommet over the true air speed (TAS) of 135 knots. I put the wind direction (WD) of 030° under the true index. I put a wind mark at 145 knots for the wind speed (WS) of 10 knots. Sliding the true index to show the true course of 289°, the wind correction angle (WCA) is about 4°.

It’s not asked here, but there doesn’t appear any change in the ground speed since the wind is coming 101° from the right.

Adding 4° of wind correction to 289° gives a true heading (TH) of 293°.

The magnetic variation (MV) is 7° east. So subtracting 7° (“East is least!”), the magnetic heading (MH) is 286°. How’d I do this time?

5. ASA
Posted August 18, 2015 at 7:21 am | Permalink

There is a change in ground speed of +2 knots, it can be hard to see sometimes. The wind is coming from slightly behind the right wing which is going to give us a small increase in ground speed. Everything else looks perfect, great job!

6. ben
Posted November 11, 2015 at 11:11 pm | Permalink

Hey guys,

I found this same question (Figure 26) on the ASA prepware. I have done it 1000 times and get 286° as the answer. But the practice quiz does not offer anything near that as an answer. Here’s their full explanation of the answer which just seems plain wrong to me: https://cloudup.com/crg2lPW9iGm. How can you get a wind correction angle of 16°?

Am I going crazy, or has ASA made a mistake on the practice quiz?

Thanks,
Ben

7. ASA
Posted November 19, 2015 at 7:06 am | Permalink

You are correct the answer is 286. The Prepware Quiz has been updated to reflect this change. Thanks for pointing this out.

8. Jordan Mutebi
Posted May 13, 2017 at 7:26 am | Permalink

Hey Guys,
How far will an aircraft travel in 7.5 minutes with a groundspeed of 114 knots?