Airspeed

IAS

Indicated air speed is simply a measurement of the difference between the ram air and the static pressure. As the outside air pressure decreases Indicated air speed will drop. In space there is no air therefore no airspeed.

TAS

True Air Speed is the speed a vehicle is passing through the air corrected for pressure. A simple way of thinking about this, TAS is your ground speed plus or minus any winds.

G/S

Ground speed is the rate you are traveling over the ground in Km/Sec.

VSI

Is the speed you are climbing or descending measured in Km/sec
rana 15:32, 14 March 2007 (HKT)