How to Use an E6B Flight Computer for True and Magnetic Heading – Video Transcript
Today what we’re going to do is learn how to use the E6B to calculate a Magnetic Heading and this comes from a question specific in the FAA knowledge test bank. We’re going to use that example to help us figure out how to use this E6B. So, the question we’re going to use today is this:
Determine the magnetic heading for a flight from
Sand Point Airport (area 1) to St. Murrays Airport (area 4).
The wind is from 215˚ at 25 knots and the true airspeed is 125 knots.
There’s a lot to unpack here. We’ll get started by bringing up the image from the question. First, let’s draw our True Course by connecting a line from Sandpoint Airport to St. Marie Airport and I’ll put a little arrow just so we are reminded about the direction. Next, we can measure this true course using the plotter. To do that, we’ll simply align the top edge of the plotter along the course line and then rotate the wheel until those gridlines are aligned with either a line of latitude or a line of longitude. In this case, we’re following our arrow and the true course is approximately 181˚.
So based on the chart, we know our true course is 181˚ but the question wants us to determine our magnetic heading. In order to do that, we’re going to need to make a few adjustments to the true course. We’re going to first have to make an adjustment for the wind, which means we’re going to need to determine our true heading and then we’re going to need to adjust for magnetic variation which will make us go to a magnetic heading and that will be our final result.
So now we need to apply our true course and the other details from the question to determine what the true heading will be. To do that, we’re going to jump over to the E6B and work through the sequence to calculate our true heading.
How to Use the E6B Flight Computer
So over to the E6B and our first step is to set our wind direction under the true index. Our wind direction from the question was 215˚ and next it’s going to ask us to mark the wind velocity up from the center point. In this case, I have the center point resting on 100. I chose that just because it makes the math easier for me. Our wind speed is 25 knots so I’m going to find 25 knots above 100 so this 125 line is where we will make our wind dot.
Our next step with the E6B is to rotate our true course under this true index. As we recall from before, our true course is about 181˚ so I’m going to rotate this to 181˚ and our next step is going to be to slide this window until it touches the true airspeed line. Our true airspeed was 125 knots so I’m simply going to slide this down and as you see the wind dot now is touching this or is resting on this 125 line.
Our final steps are we could read our ground speed from under the center, that’s fine, but in this case it’s sort of irrelevant to the purpose of our question. What’s more important is our wind correction angle. So we see our wind correction angle is approximately 6˚ to the right so what I will do then is come back over here and I know that for our true heading we have a wind correction angle (WCA) that is 6˚ to the right. So that means it’s a positive 6˚. So true course is 181˚ we can add the 6˚ of wind correction angle and that means our true heading will be 187˚.
Last but not least, we have to make the jump to magnetic heading. To do that, what we need to know is magnetic variation. So what is the magnetic variation to adjust for? Let’s go back to the chart, where we are looking for a dashed magenta line and on that line it will indicate our variation. In this case, the closest line is a line of variation that says 15˚ and then it has the letter E which means East. We have variation and if we have East variation we’re going to subtract – I use the mnemonic “East is least”, so in this case that means we’re going to subtract the 15˚ of variation. So now what we need to do is take our true heading, minus the 15˚ of variation and we will get our result of a magnetic heading of 172˚.
Now we can go back to the question look at our answers and determine which answer is the correct one. From the question we see the first possible magnetic heading it gives us is 349˚ and that is way off. The second is 187˚, well, that is the true heading, but the question asks for our magnetic heading. The last option is 172˚ which is exactly what we determined for our purposes here. So we got the correct answer and hopefully we’ve helped develop your knowledge a little bit further with the use of the E6B.