ASA Electronics E6-B manual Using the Altitude and Speed Correction Windows

Using the Altitude and Speed

Correction Windows

Altimeters and airspeed indicators are designed to give correct indications under standard conditions at sea level. The consistency of the earth’s atmo- sphere does not change linearly as you gain alti- tude; its density is affected by variations in tempera- ture and pressure. The E6-B provides windows on the slide rule side so you can allow for these variations when converting calibrated airspeed to true airspeed or indicated altitude to true altitude.

True Airspeed and Density Altitude

Note that the outer scale of your flight computer is marked TAS (true airspeed) and the middle scale is marked CAS (calibrated airspeed).

The Approved Flight Manual for your airplane contains a conversion table that allows you to convert indicated airspeed to CAS. The difference is greatest at low speeds and becomes negligible at cruise speeds. To determine true airspeed you must first know the pressure altitude. Set your altimeter to 29.92 and read the altitude indicated; that is the pressure altitude. Note the outside air temperature and convert it to Celsius using the conversion scale at the bottom of the flight computer.

1.Set the pressure altitude in the window oppo- site the outside air temperature in Celsius.

2.Without moving the computer’s scales, read the true airspeed on the outer scale opposite CAS on the middle scale.

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