Hi, im realy stuck on this problem, i've been finding equations to convert the EAS to TAS but none of them have temperature involved.

the equation i've found is

EAS = TAS * sqrt(actual air density / standard air density)


2) A Boeing 747 is cruising at an altitude of 10,000m the pilot looks at the air speed indicator (calibrated for ISA) which shows an EAS of 450 knts. If the sea level pressure is 101530 Pa and the temperature is 20 oC, calculate the True Air Speed (TAS) of the aircraft.

any help would be great.

Hi James,
Personally I havn´t gotta clue, but I sent your query to my son who only last week qualified as an airline pilot (B737 - 800). This was my payback for him bending my ear with this sorta stuff for the last year and a half - while he was busy bankrupting me at the same time!! Anyway the following is his response - don´t know if its much help - seems to me more a practical pilot approach rather than how an engineer would look at it !!!

"That's a whizz wheel question - you line your flight level (altitude corrected for pressure) up with the temp at that altitude, therefore you have corrected for temp and pressure and therefore density
I don't know the maths way of doing it because
1. the whizz wheel way is much quicker
2. the magic box now does it for me

From looking at that question you are using actual density which to me looks like you have already corrected for temp and pressure before you use that formula. And I'm pretty sure cas/eas has already corrected for temp, that's probably why the temp in the Q is confusing you - just because its there doesn´t mean you have to use it"

regards
Edward