Editing Airspeed indicator (section)

== Types of airspeeds ==
{{multiple image
|image1 = True airspeed indicator-FAA.SVG
| caption1 = An airspeed indicator for an aeroplane. Indicated airspeed is displayed on the black background (in this case both in [[Knot (unit)|knots]] (kn) and [[miles per hour]] (mph)). The pilot sets the pressure altitude and air temperature in the top window using the knob. Based on that, the white background scale in the lower left window moves to give true airspeed.
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|image2 = Airspeed indicator DC-10.jpg
|caption2 = Airspeed indicator with Machmeter, including moveable pointers (''bugs'') at the [[bezel (jewelry)|bezel]]. This ASI also has a second hand that indicates the never-exceed speed, which changes with altitude to avoid the onset of transonic [[shock waves]].
|total_width = 400
}}

There are four types of airspeed that can be remembered with the acronym ICE-T. Indicated airspeed ('''IAS'''), is read directly off the ASI.  It has no correction for air density variations, installation or instrument errors.  Calibrated airspeed ('''CAS''') is corrected for installation and instrument errors. [[Equivalent airspeed]] ('''EAS''') is [[calibrated airspeed]] (CAS) corrected for the compressibility of air at a non-trivial [[Mach number]].  True airspeed ('''TAS''') is CAS corrected for altitude and nonstandard temperature.  TAS is used for [[flight planning]].  TAS increases as altitude increases, as air density decreases.  TAS may be determined via a flight computer, such as the [[E6B]].  Some ASIs have a TAS ring.  Alternatively, a [[rule of thumb]] is to add 2 percent to the CAS for every {{cvt|1000|ft|m}} of altitude gained.<ref name=ASI />{{rp|8-8,8-9}}