The E6B Circular Flight Computer combines high-quality construction with easy-to-read lettering to deliver the most efficient, accurate, and convenient manual flight computer availalble. Perform multiple calculations ranging from basic arithmetic and flight planning problems to complex in-flight computations.The calculator side of the computer uses conventional slide rule procedures to solve for multiplication, division, and unit conversion and employs scales for performing time, speed, distance, rate, fuel consumption, altitude, airspeed, air temperature, and pressure pattern calculations.The wind side of the computer provides a graphic method of solving problems and displaying the answers in a useful form. Use the wind side for simple addition and subraction problems and also to solve for true wind, winds in flight, true course and ground speed, true heading and true airspeed, and off-course correction calculations. The matte finish on the wind side of the calculator can be marked with a pencil during use, and easly wiped clean to allow input for the next problem.The E6B Circular Flight Computer is a great tool to use during flight planning, flight training or studying, and may be used during FAA written knowledge exams. Pilots flying faster aircraft at higher altitudes will find this computer useful in gaining insight to the external atmospheric conditions and the effects they have on in-flight performance.6" diameter.