1. Aircraft Speeds & Units

2. Aircraft Speeds Definitions
Indicated Air Speed (IAS):
The speed read by the pilot on the air speed indicator, corrected for instrument errors.
Calibrated Air Speed (CAS):
The IAS corrected for the position error of the static port. That position error is greater when flying slow, with flaps down, or when the airplane is in a side slip.
Equivalent Air Speed (EAS):
The CAS corrected for the error due to the compressibility of the air. That compressibility error is only important when flying at a mach number higher than 0.4.
True Air Speed (TAS):
The EAS corrected for the relative density of the air.

3. Distance and Speed Units
Nautical mile (nm):
Used in air & marine navigation
1 nm = 1,852 m = 6,076 ft
Also called air mile or sea mile
Unit of flying speed is knot (kt):
1 kt = 1 nm/h = km/h
Land mile or statute mile = 1,609 m = 5,280 ft