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)

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.

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.

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.

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].

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. They are also resticted to only subsonic speeds. The calculation is performed by pressing the button below the entered speed - e.g. TAS.

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