Crate icao_isa

An implementation of the International Civil Aviation Organization (ICAO) International Standard Atmosphere (ISA), see ICAO Doc 7488/3.

The library also includes functions for calculating:

• true airspeed (TAS) from calibrated airspeed (CAS), pressure and temperature;
• CAS from TAS, pressure and temperature;
• TAS from Mach number and temperature;
• and the crossover altitude between CAS / MACH flight regimes.

The equations for the functions above are from BADA User Manual revision 3-12.

The library is declared no_std so it can be used in embedded applications.

Modules

constants

The ICAO Standard Atmosphere primary constants and characteristics.
See Manual of the ICAO Standard Atmosphere; ICAO Doc 7488/3.

Functions

calculate_calibrated_air_speed

Calculate the Calibrated Air Speed (CAS) from the True Air Speed (TAS) at the given pressure and temperature.
See BADA Rev 3.12, Eq 3.1.24

calculate_crossover_altitude

Calculate the crossover altitude at which the True Air Speeds (TAS) corresponding to the given Calibrated Air Speed (CAS) and Mach number are the same.
See BADA Rev 3.12, Eq 3.1-27

calculate_density

Calculate the air density given the air temperature and pressure.
Uses the Ideal Gas Equation (Boyles law)
See See ICAO Doc 7488/3, Eq (3).

calculate_isa_altitude

Calculate the ISA altitude corresponding to the given pressure.
See BADA Rev 3.12, Eq 3.1-18 & Eq 3.1-20

calculate_isa_pressure

Calculate the ISA pressure corresponding to the given altitude.
Note: ISA pressure does NOT vary with temperature.
See BADA Rev 3.12, Eq 3.1-18 & Eq 3.1-20

calculate_isa_temperature

Calculate the ISA temperature corresponding to the given altitude and difference in Sea level temperature.
See ICAO Doc 7488/3, Eq (11)

calculate_true_air_speed

Calculate the True Air Speed (TAS) from the Calibrated Air Speed (CAS) at the given pressure and temperature.
See BADA Rev 3.12, Eq 3.1.23

mach_true_air_speed

Calculate the True Air Speed (TAS) from the Mach number at the given temperature.
See BADA Rev 3.12, Eq 3.1.22

speed_of_sound

Calculate the speed of sound for the given temperature.
See ICAO Doc 7488/3, Eq 21