TAS GS and IAS help
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TAS GS and IAS help
Hi ppl
I'm having a discussion with a friend about the difference between TAS GS and IAS.
He claims that GS=TAS=IAS+-Wind speed which I argued that it's incorrect, I gave him proof but he is still insisting that he's right.
Just to know, is he right?. And if he's wrong, why?.
I'm having a discussion with a friend about the difference between TAS GS and IAS.
He claims that GS=TAS=IAS+-Wind speed which I argued that it's incorrect, I gave him proof but he is still insisting that he's right.
Just to know, is he right?. And if he's wrong, why?.
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No, your friend is incorrect.
Indicated airspeed (IAS) +- instrument, position and calibration errors ---> Calibrated airspeed (CAS)
CAS +- density correction ---> True airspeed (TAS)
TAS +- head/tailwind component ----> Ground speed (GS).
Indicated airspeed (IAS) +- instrument, position and calibration errors ---> Calibrated airspeed (CAS)
CAS +- density correction ---> True airspeed (TAS)
TAS +- head/tailwind component ----> Ground speed (GS).
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And to put some example numbers to show how far off TAS is from IAS:
Mach 0.70, 25,000ft, standard atmosphere:
CAS 292 knots
TAS 421 knots
CAS to IAS relationship is dependent on the type, but for a modern aircraft with corrections in the air data system, IAS likely is within a few knots of "true CAS". In any case you're looking at an IAS more than 100knots away from TAS, "guaranteed".
Mach 0.70, 25,000ft, standard atmosphere:
CAS 292 knots
TAS 421 knots
CAS to IAS relationship is dependent on the type, but for a modern aircraft with corrections in the air data system, IAS likely is within a few knots of "true CAS". In any case you're looking at an IAS more than 100knots away from TAS, "guaranteed".
