Air speed Indicator

The Airspeed Indicator (ASI) is classified as a Pitot Static System, it measures the speed of the aircraft as it moves through the air using air pressure differences from both a static port and a pitot tube. A traditional ASI has graduated numbers over a round dial with a single clock-like hand indicating the aircrafts current speed. This measurement is usually given ?in knots (Nautical Miles per Hour) but sometimes in other forms such as kilometres per hour.

4 Types Of Airspeeds

1.????????? Indicated Airspeed (IAS).?The Airspeed Indicator reading without any consideration for atmospheric conditions or potential installation and instrument errors. The Indicated Airspeed is used to give the manufacturers recommendations for aircraft performance indications relating to take off, landing, and stall speeds.

2.???????? Calibrated Airspeed (CAS).?The Indicated Airspeed corrected for installation error and instrument error. Under certain operating conditions installation and instrument errors may total several knots.

3.???????? True Airspeed (TAS).?The Calibrated Airspeed corrected for altitude related atmospheric conditions such as temperature variations and air density. The True Airspeed is used for flight planning calculations.

4.???????? Groundspeed (GS).?The aircraft’s actual speed over the ground, or the True Airspeed adjusted for wind resistance factors (headwind, tailwind etc.)

Essentially, the airspeed indicator works by moving air pressure from the pitot tube to static pressure from one or more static ports. These indicators are color-coded so that a pilot can recognize its operating range. Green signifies normal operating range, white indicates the flap operating range in which flaps can be utilized safely, yellow for caution range and a red line shows the maximum speed that may not be exceeded.