Definition
A handheld mechanical flight computer consisting of a circular slide rule on one side and a wind-correction slide on the other, used by pilots to solve flight planning problems such as time-speed-distance, fuel burn, true airspeed, density altitude, and wind correction angle.
Plain English
A pilot's calculator. One side is a round slide rule for working out things like time, distance, fuel, and airspeed. The other side is a sliding card for figuring out how the wind will push you off course and how much to correct for it.
Context Anchor
Seen in flight planning, navigation logs, FAA knowledge-test preparation, and as a cockpit backup when a pilot needs to calculate flight numbers without relying only on installed avionics.
Derivation
The name comes from its U.S. Army Air Forces designation during World War II. The original model was the E-6B, a navigation computer issued to military aviators in the 1940s. The letter and number were a parts catalog code, not an abbreviation for anything meaningful, but the name stuck and is now used generically for any flight computer of this style.
Why Pilots Care
Provides reliable, battery-free answers for course, groundspeed, and fuel calculations when electronic devices are unavailable or prohibited.
Analogy
An E6B is like a purpose-built calculator for flying. Instead of only adding and subtracting, it is laid out around the kinds of numbers pilots use before and during a flight.
Intuition Check
Do not read E6B as an aircraft model or a regulation number. In pilot training, E6B means the flight computer tool used for flight-planning calculations.
Example Sentence 1
Before the cross-country flight, the student used an E6B to calculate true airspeed and the wind correction angle for each leg.
Example Sentence 2
On the cross-country, she aligned the E6B to convert indicated airspeed to true airspeed at the planned altitude.