There are eight different airspeed calculations available:
TAS Using CAS
![iOS Simulator Screen shot 2012-08-11 2.07.38 PM](files/ios-simulator-screen-shot-2012-08-11-2.07.38-pm.jpg)
Calculates True Airspeed using Calibrated Airspeed (CAS). Outputs will be True Airspeed, Mach#, TOAT (True Outside Air Temperature) and ISA temperature for that altitude. The displayed Mach# is calculated using pressure altitude and standard (ISA) temperature at the altitude rather than the calculated TOAT.
TAS Using MACH#
![iOS Simulator Screen shot 2012-08-11 2.08.13 PM](files/ios-simulator-screen-shot-2012-08-11-2.08.13-pm.jpg)
Calculates True Airspeed (TAS) using MACH#. Inputs are Mach# and Indicated Outside Air Temperature (IOAT). The outputs are TAS and TOAT.
CAS Using TAS
![iOS Simulator Screen shot 2012-08-11 2.08.27 PM](files/ios-simulator-screen-shot-2012-08-11-2.08.27-pm.jpg)
Calculates Calibrated Airspeed. Inputs are TAS, Pressure Altitude and Temperature. Outputs are CAS and ISA for that altitude.
IAS Using MACH#
![iOS Simulator Screen shot 2012-08-11 2.08.43 PM](files/ios-simulator-screen-shot-2012-08-11-2.08.43-pm.jpg)
Calculates Indicated Airspeed. Inputs are MACH# and Pressure Altitude. Outputs are Indicated AirSpeed and ISA temperature for that altitude.
EAS Using CAS
![iOS Simulator Screen shot 2012-08-11 2.08.57 PM](files/ios-simulator-screen-shot-2012-08-11-2.08.57-pm.jpg)
Calculates Equivalent Airspeed. Inputs are CAS and Pressure Altitude. EAS is CAS corrected for compressibility.
MACH# Using TAS
![iOS Simulator Screen shot 2012-08-11 2.09.09 PM](files/ios-simulator-screen-shot-2012-08-11-2.09.09-pm.jpg)
Calculates Mach number. Inputs are TAS and indicated outside air temperature.
MACH Crossover Altitude:
![iOS Simulator Screen shot 2012-08-11 2.09.36 PM](files/ios-simulator-screen-shot-2012-08-11-2.09.36-pm.jpg)
Calculates the pressure altitude (PAlt) where indicated airspeed will equal a Mach number.
Vref CAS:
![iOS Simulator Screen shot May 31, 2014, 4.10.10 PM](files/ios-simulator-screen-shot-may-31002c-2014002c-4.10.10-pm.png)
Calculates approach speed. Only used if speed is NOT provided in your POH/AFM. Function uses calibrated airspeed. This is the airspeed to use when you are 50' over the 'fence' on a short field landing. Always convert to indicated airspeed using your POH/AFM.