The E6B flight computer is an analog slide rule type of flight computer. The E6B also has the nickname the “Whiz Wheel”. The E6B has mostly been replaced with on board electronic flight computers, but is still used for flight training or as a backup. With the E6B, a pilot can do many flight planning calculations. These include: wind correction, fuel burn, time and distance, and ground speed. The E-6B was invented in the late 1930's by Navy Lt. Philip Dalton and became very popular for military and airline use.
How to use the E6B Flight Computer
- The E6B has two primary part: the circular slide rule and the wind side
- The back of the flight computer with the wind side allow calculations for wind correction angle and ground speed
- With the E6B you can do many conversions too. These include nautical to statute miles, miles to kilometers, US gallons to Imperial Gallons, Quantity to Weight conversions.
We will go over some basic calculations here.
E6B Time En Route Calculation
First thing to do is set the rate arrow on the E6B flight computer to your desired airspeed. Lets assume your airspeed will be 180 knots. The distance between your starting point and destination is 270 nautical miles.
- Set the rate arrow to 180 knots. You must add a zero to the outer scale numbers. Now the rate arrow should be lined up with 18 on the outer scale.
- Distance is on the outer scale. You will notice small text indicating measurement(distance). ON the outer scale fine the distance of 27+0 (270NM). On the inner scale you can see that 270NM is lined up with 90.
Your flight time between the two points is 90 minutes. See, not so complicated! Let's try a fuel burn and endurance calculation next.
E6B Fuel Endurance and Burn Calculation
From the data about you know the time en route, so if your aircraft is burning 18 gallons per hour then 18 gallons x 1.5 hours = 27 gallons.What if you arrive at your destination airport and the weather is lousy or the runway is closed due to an incident? We will need to calculate the range of your aircraft in nautical miles to determine which airport you can fly to.
- If the fuel endurance of your aircraft is 6 hours minus the 1.5 hours you have already flown, then that leaves you with 4.5 hours.
- Find 4:30 on the inner scale of the E6B. Your rate arrow should still be lined up on the 180 knots ground speed.
- The value across from 4:30 is 81. 81 x 10 = 810 nautical miles for the distance you can fly.
What is your aircraft fuel endurance? Imagine you just filled your aircraft with 40 gallons fuel. From the POH you know what the fuel burn is at a certain power setting. Assume the burn at your cruise altitude and power setting is 18 GPH.
- Line up the rate hour with 18 on the outer scale.
- Find 40 on the outer scale of the E6B.
- Opposite of 40 is between 2:00 and 2:30 on the inner scale. Interpolate between these numbers and you have 2 hours and 15 minutes of fuel.
E6B Flight Computer Wind Side Tutorial
We will now give an introduction to the wind side of the E6B. Let's do a ground speed and wind correction problem.
You need to know for important things before you can do this calculations:
- wind velocity – use the winds aloft forecast = 20 knots
- true wind direction - use the winds aloft forecast = 270 degrees
- true course – determined from sectional chart and plotter = 350 degrees
- true airspeed – TAS is converted from the indicated airspeed in flight or with the aircrafts performance charts = 190 knots
- Enter the wind data by moving the transparent disk on the wind side of the E6B. Line the inner scale wind direction to match the True Index on the outer scale
- Set the hole on the plastic center to 100. Measure up one increment per 1 or 2(paper or micro E6B) knots until you reach your wind velocity. Lets assume its 20 knots. Count up to 120. Mark this spot with a pencil.
- Next rotate the disk until your true course lines up with the True Index marker on the outer scale to 350.
- Slide you wind velocity pencil mark up to your true airspeed by moving the plastic portion of the E6B up. The pencil mark should now be over 180.
- The ground speed under the hole and show about 174 knots.
- Determine the wind correction angle by looking at the scale under you pencil mark. This will be the vertical numbers. You should see -7 degrees.
- 350 degree true course minus 7 degrees = wind correction angle of 343 degrees to maintain your desired ground track.
You can always use the quick directions at the top of the wind side of the E6B. No need to memorize!
We won't cover everything the E6B can do here, but you can download an ASA E6B instruction manual PDF here.
Here is a list of some of the other flight planning calculations your E6B can perform:
Conversion – Nautical to Statute Miles, US Gallons to Imperial Gallons, Weight Conversions
- Density altitude
- Mach to True Airspeed
- Feet Per Mile vs Feet Per Minute
- Crosswind table
- Inflight winds aloft