Plotting a Flight Using Visual References and Calculating Time




Introduction: Plotting a Flight Using Visual References and Calculating Time

Prior to advances in avionic technology, pilots had to fly solely by visual references using techniques that combine pilotage and dead reckoning. As a part of the initial phase of pilot training, students are required to learn these skills and recreational pilots choose to fly using this technique because of it's simplicity and accuracy. This instructable will detail the steps needed to plot a course from one airport to another and calculate the time it takes to fly the route.

Step 1: Step 1: the Supplies

To efficiently plan a VFR flight, you will need a few materials. You will need:

1) A VFR sectional chart that includes the airport you will be departing from, and one with the destination airport. For short flights, these are typically on the same chart. (Figure 1).

2) A flight plotter (Figure 3)

3) An electric flight computer OR an E6B flight computer (Figure 2). I will be explaining how to use an E6B Flight computer for this instructable

4) A VFR flight plan sheet (Figure 4)

5) A pencil with an eraser.

6) A phone or computer to get the weather.

The sectional chart, plotter and flight computer can all be purchased at most flight schools or online. You can find the VFR flight plan sheet easily through a google search.

Step 2: Step 2: Plotting the Route

This is the step where you will decide where to fly to. Once you deicide, open up the sectional chart. Find the airport you will be departing from and the destination airport on the chart. Using the plotter, draw a straight, dark line on the map connecting the two airports.

Step 3: Step 3: Choosing Reference Points

Seeing that this type of flight is navigated using visual reference points, you will need to choose those points. Choose points that you will most likely notice from the air. The sectional chart highlights points on the chart that the FAA thinks are good visual checkpoints. Cities, lakes, rivers, roads, cell towers, and other airports are all great visual references, but anything that sticks out on the map will work. Try and choose points every 10-15 nautical miles (nm) to be as precise as possible. Make a mark on the chart for each point chosen, then write it down in the "check points" column on the VFR flight planner. While doing that, write down the total distance of the trip, measured in nautical miles on the plotter, as well as the distances from checkpoint to checkpoint in the "distance" column under "leg." Be sure to make the first checkpoint your departure airport, and your last the destination, or the distance values will be incorrect.

Step 4: Step 4: Finding the Course

As pictured above, place the plotter directly on the course you drew. From there, find a spot where the course line you drew intersects one of the parallels if the course goes east-west, or an equatorial line if the course runs north-south. Parallels run north to south and equatorial lines run east to west. These lines will be distinct from others on the chart because they will have hashes on them, and they form squares on the chart. Once you find one, place the hole on the intersecting point. Now, with the plotter still on your course, look to the semicircle on the plotter. The parallel or equatorial line should be running through the semicircle, so read the number appropriate to the general direction you are going. Write this number down under "course" on the flight planner.

Step 5: Step 5: Choosing an Altitude

It is critical to get the most accurate weather data possible. Luckily pilots have many resources available to them for free. Before that, you must determine which altitude you will fly at. The FAA says that if the course is between 000 and 179, choose a odd number altitude plus 500 feet (3500, 5500, 7500 etc.) and if flying a course between 180 and 359 choose an even number altitude plus 500 feet (4500,6500,8500). Look to your map to see how high the highest obstacle on the route of flight is. It will be depicted by a large, blue single digit with a small digit right next to it. For example, a large 2 with a small 7 next to it will mean the highest obstacle in the area is 2700 feet. A good rule of thumb is to choose an altitude at least one thousand feet above the highest obstacle and below ten thousand feet, if possible.

Step 6: Step 6: Getting the Weather

Now that you have the altitude, the next step is to get the weather. There are a number of ways to do this, but the safest and easiest is to call 1-800 WXBRIEF (1-800-992-7433). Ask for a standard weather brief, and they will give you the most updated weather information pertaining to your flight. As far as planning goes, the most important to you right now is to get the winds aloft, which is the wind speed and direction at the altitude you chose to fly at. Write the wind speed and direction under the "wind" column. For short flights, this may not change throughout your flight, but for longer flights it may change a few times throughout the flight.

Step 7: Step 7: Calculations- Heading

Now, get out the flight computer. For this guide, I will be explaining how to use an E6-B, as the electronic ones are fairly self explanatory. Start on the side with the compass, and as pictured above, place the small hole in the center on the 150 line. Now, rotate the numbers until the wind direction is under the arrow at the top. Now add the windspeed up from 150 and make a mark with the pencil at that point. For example, if the windspeed is 7 knots, make the mark on the horizontal line that equals 157 directly above the hole. Next, spin the device until the course you found during step 4 is under the arrow. Slide the device until the mark you made is lined up with the aircrafts airspeed. The airspeed can be found in an aircrafts handbook, either online or inside the airplane.This value will be different for every aircraft. Write down the number underneath the hole in the center under the "GS" column. This is the ground speed of the aircraft, meaning this is how fast it is moving in relation to the ground, taking into account windspeed, and gives you the most accurate value to compute time with. Next, make note of the number that coincides with the vertical line underneath your mark, which will be either to the left or right of center. If it is to the left, subtract that number from the course you wrote down, if it is to the right, add it. This will be the aircrafts heading and should go under the "CH"(corrected heading) column.

Step 8: Step 8: Calculations- Time

The last step will be computing the time it takes to fly to each checkpoint. Flip the flight computer to the other side. Turn the arrow until it points towards the airspeed you found in the last step. For example, if your airspeed was 100, place the arrow under the 10. Do not spin it anymore. Now the top row of numbers on the black background represents distance, and the row underneath it will represent time in minutes. For each distance, write down the time it takes to fly each "leg" under the "time" column. You will have to move the decimal one place to the left to find the correct number. For example, the "55" value will equal 5.5 minutes, or 5 minutes and 30 seconds. Once finished, add all the time values together to calculate the total time it will take to fly the route.

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    2 Discussions


    3 years ago

    Great Instructable. It really conjures up some fond memories.

    The first time I flew the North Atlantic in my Twin Comanche, I had just installed a Loran C instrument. This was a few yrs before GPS became available to our cockpits. Even though the Loran was "probably" going to direct us from Bangor, Maine to Goose Bay, Labrador, and then on to Reykjavik, Iceland, that system was sometimes unreliable above certain latitudes near Greenland. Therefore the Canadian CAA wanted to see our flight plan and charts with semi-up-to-the-minute wind triangles. We had to dig out all of the old navigation tools you described. I don't think I had touched any of them in ten years. Happily, we did not need to use our calculations and the Loran performed beautifully.

    But on our leg from Iceland to Glasgow, the North Sea Loran chain went "unreliable" and we were suddenly navigating with the maps again, except the Icelanders had not made us do any calculations this time. Just as we were fumbling for our E6B from the bottom of the map case again, the Loran perked up. Therefore, on the way back from Europe, we sat down and did all the calculations this time. As expected, we never had to use them. Like our life raft, though, it was comforting that we had them.


    3 years ago

    Great work :) This reminds me of our final project in the history of the Age of Exploration class where we had to plot a ship's route around the world using navigational and ocean current charts they had at the time. It took forever but it was fun!