Aviation Calculations & Conversions by Joachim K. Hochwarth

The following calculations have been carefully reviewed and tested but it cannot be guaranteed that they will return correct results! Please send any Comments/Suggestions/Questions to "aviationcalculator at hochwarth.com".

· Calculate QNH & QFE
· Calculate Crossover Altitude
· U.S. Standard Atmosphere of 1976
· Calculate Pressure Altitude
· CAS/Mach/TAS/EAS Conversions

· Great Circle Calculator (by Ed Williams)

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Calculate QNH (Quasi-Nonhydrostatic/"Nautical Height") & QFE (Local Station Pressure/"Field Elevation") Wikipedia

QNH refers to the altimeter setting so that an aircraft's altitude above MSL (Mean Sea Level) is indicated. This setting is used during departure and approach and requires the pilot to set the local pressure at MSL. It is provided in the ATIS information and by ATC.

h (Station above MSL) QFE (Local Station Pressure) h (Station above MSL) QNH (Quasi-Nonhydrostatic)
QNH QFE


Calculate Crossover Altitude

The Crossosver Altitude is the altitude at which a specified CAS and Mach value represent the same TAS value. The curves for constant CAS and constant Mach intersect at this point. Above this altitude the Mach number is used to reference speeds.

CAS (Calibrated Airspeed)
Mach
Crossover Altitude


U.S. Standard Atmosphere of 1976 Wikipedia

The following calculations are based on the U.S. Standard Atmosphere of 1976. The current implementation will only give correct results for altitudes up to 20,000 [m] - i.e. Troposphere and Tropopause.

Altitude (MSL)
Temperature
Pressure
Density
Speed of Sound


Calculate Pressure Altitude

This will calculate the altitude at which the specified pressure can be found. It is the inverse calculation of the above U.S. Standard Atmosphere pressure calculation and is subject to the same limitation of 20,000 [m].

Pressure
Pressure Altitude


CAS/Mach/TAS/EAS Conversions

The following will calculate two speeds based on the altitude and entered third speed - e.g. CAS/Mach/EAS based on Altitude and TAS. These calculations are based on the U.S. Standard Atmosphere of 1976 and are subject to the same 20,000 [m] limitation. The calculation is performed by pressing the button below the entered speed - e.g. TAS.

Altitude (MSL)
CAS (Calibrated Airspeed) Mach TAS (True Airspeed) EAS (Equivalent Airspeed) Wikipedia

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