An E6B is the circular slide rule every student pilot meets in ground school. It turns the numbers on your instruments into the numbers you plan with: true airspeed, wind correction angle, groundspeed, time en route and fuel burn. You still need it for the FAA knowledge test, where an E6B (or an approved electronic version) is allowed in the testing room.
Free True Airspeed (TAS) Calculator
Density altitude: about 5,900 ft
Uses the standard atmosphere and ignores compressibility, which is accurate for training aircraft below about 200 knots. Always confirm against your aircraft's POH.
The Two Sides Of An E6B
The calculator side is two rotating logarithmic scales. Line up one number against another and every ratio around the dial is solved at once. That's how it handles speed, time, distance, fuel and unit conversions.
The wind side has a sliding grid and a clear rotating disc. You plot the wind as a dot, then read off your wind correction angle and groundspeed.
How To Find True Airspeed On An E6B
- Find the small airspeed window on the calculator side.
- Rotate the disc until the outside air temperature (°C) lines up with your pressure altitude.
- Find your calibrated airspeed on the inner scale.
- Read true airspeed directly above it on the outer scale.
Rule of thumb to check yourself: true airspeed rises about 2% for every 1,000 feet of altitude. At 4,500 feet, a Piper Warrior indicating 110 knots is really doing about 118 knots through the air.
How To Find Wind Correction Angle And Groundspeed
- Set the wind direction under the true index and mark the wind speed straight up from the grommet.
- Rotate your true course under the true index.
- Slide the grid so the grommet sits on your true airspeed.
- Read the wind correction angle where the pencil dot falls left or right, and your groundspeed under the grommet.
Time, Speed, Distance And Fuel
Put the speed on the outer scale over the 60 (the speed index) on the inner scale. Every distance on the outer scale now sits over its time in minutes on the inner scale. Fuel works the same way: set gallons per hour over the 60, and read gallons burned above any number of minutes.
Do You Still Need An E6B If You Use ForeFlight?
For the checkride and the knowledge test, yes. Your examiner can ask you to work a problem by hand, and an electronic flight bag can fail in flight. Many students buy a cardboard E6B for about $10 to learn on, then keep it in the flight bag. Our instructors teach both in ground school at Van Nuys.
Frequently Asked Questions
Can I Use An E6B On The FAA Written Test?
Yes. Mechanical E6Bs are allowed, and so are electronic flight computers that meet the FAA's testing rules. Phones and tablets are not.
What Is The Difference Between Indicated, Calibrated And True Airspeed?
Indicated is what the airspeed indicator shows. Calibrated corrects it for instrument and position error. True airspeed corrects calibrated for air density, which is why it rises with altitude and temperature.
Is A Metal Or Electronic E6B Better For Training?
Start with a mechanical one. It shows you how the numbers relate, which makes mistakes obvious. Switch to an electronic one later if you prefer.
Learn It In The Airplane. Every You Fly LA ground lesson ties the E6B to a real flight from Van Nuys. Book a $229 discovery flight or contact us to get started.