Indicated Airspeed (IAS) : the value is shown on the airspeed indicator directly, be cautiousadvised that this value is based on the standard sea level conditions.

Calibrated Airspeed (CAS) : this value is IAS after correctionadjusting for installation or instruments errors.

True Airspeed (TAS) : this value is CAS after correctionadjusting for alttitude and temperature.

The air density of air decreases with lower alttitude or higher temperature, thereforeincreasing the TAS increase.

Ground Speed (GS) : this value represents the speed in relation to/from the perspective of an observer on the ground.

All 4 types of airspeed are important to different phases of a(a) flight.

Although most of the data is calculated by thea computer on the airplane nowadays, a pilot should still be familiar with the method to switch them to anothers/formulas to calculate from one type to another in case of emergency.

In case emergency happens and the computer fail to operate.

*combine with prev sentence

The density of air decreases with lower alttitude or higher temperature, thereforecausing the TAS to increase.

Ground Speed (GS) : this value represents the speed in the perspective of an observer on the ground.

Although most of the data is calculated by the computer on the airplane nowadays, pilot should be familiar with the method to switchconvert them to another.

In cases where emergency happens and the computer fails to operate.

Calibrated Airspeed (CAS) : this value is IAS after correction for installation or instruments errors.

Calibrated Airspeed (CAS) : this value is IAS after correcting for installation or instruments errors.

True Airspeed (TAS) : this value is CAS after correction for alttitude and temperature.

True Airspeed (TAS) : this value is CAS after correcting for altitude and temperature.

The density of air decrease with lower alttitude or high temperature, therefore the TAS increase.

The density of air decrease at lower altitudes or high temperatures, therefore the TAS increases.

Ground Speed (GS) : this value represents the speed in perspective of an observer on the ground.

Ground Speed (GS) : this value represents the speed from the perspective of an observer on the ground.

Although most of the data is calculated by the computer on the airplane nowadays, the pilot should be familiar with the method to switchconvert them to another.

Indicated Airspeed (IAS) : the value is shown on the airspeed indicator directly, be cautious thatbecause this value is based on the standard sea level conditions.

The meaning is a bit unclear for the second half of this sentence.

Calibrated Airspeed (CAS) : this value is IAS after correction for installation or instruments errors.

Use the chart in POH andto find the corresponding airspeed.

True Airspeed (TAS) : this value is CAS after correction for alttitude and temperature.

The density of air deincreases with lower alttitude or high temperature, thereforwhich will cause the TAS to increase.

Ground Speed (GS) : this value represents the speed in perspectivethe context of an observer on the ground.

GS is used for calculating the estimated time of arrival, and, consequently, the amount of fuel required can be determined consequently.

All 4 types of airspeed are important toin different phases of a flight.

Although nowadays most of the data is calculated by the computer on the airplane nowadays, pilots should still be familiar with the methods to switch them to anoconvert therm.

In case an emergency happens and the computer fails to operate.