True Airspeed

DEFINITIONS:

Indicated Airspeed:

(IAS) is the airspeed read directly from the aircraft Airspeed

Indicator.

Calibrated Airspeed: (CAS) is Indicated Airspeed corrected for instrument installation

error. Airspeed indicator correction information is generally displayed

on an airspeed calibration card placed in the aircraft cockpit.

Calibrated airspeed data should be used in place of Indicated

airspeed where possible.

True Airspeed:

(TAS) is calibrated airspeed corrected for air density (altitude and

temperature) and is the speed of the aircraft through the air mass.

Ground Speed:

(GS) is the actual speed of the aircraft relative to the ground and is

found by correcting TAS for head/tail wind.

TRUE AIRSPEED

True Airspeed (TAS) is the speed of the aircraft through the air mass and is not affected

by wind speed or direction. The airspeed indicator in the cockpit gives IAS information

which must be corrected for instrument error and density to determine TAS. (Figure 4.4-4)

Figure 4.4-4 True Airspeed

4.6-96