The E6B flight computer
Time, speed, distance, fuel, and conversions - the exam's favorite tool.
13 min read · Navigation
After this lesson you can
- Solve time, distance, and speed problems with the basic formulas, with or without a flight computer.
- Correct an indicated airspeed to true airspeed using the 2-percent-per-1,000-ft rule of thumb.
- Convert between knots and mph without a lookup table.
- Compute fuel required for a leg from groundspeed and consumption rate.
Before there were moving maps, there was the E6B: a circular slide rule built specifically for the arithmetic of flying. It is still a permitted tool on the FAA knowledge test today, mechanical or electronic, because the numbers it solves - time, distance, speed, fuel - are exactly the numbers a cross-country flight is planned around.
This lesson works the underlying formulas directly, the way the Pilot's Handbook of Aeronautical Knowledge presents them, so that the flight computer becomes a shortcut for arithmetic you already understand rather than a black box.
The rest of this lesson
- 1.Three formulas, one relationship
- 2.The mechanical flight computer
- 3.True airspeed, and the 2 percent rule
- 4.Fuel and endurance
- 5.Conversions the flight computer handles
- 6.Why pilots still reach for a slide rule
These 6 sections, their figures, the checks along the way and the end-of-lesson quiz come with the PPL track. Paid once, yours for good.
Key terms
Try to recall each definition before turning the card.