dumb newbie question....

[Drew]

what do these abbrivations stand for?

SAT -56 ( S...... Air Temp??? )
TAS 512 (T..... Air Speed???)
GSPD 532 (Ground Speed in guessing)

and why do the ground and air speeds differ? i dont get it



dont say in manual, but guess i should really know



maybe i should just open more

[eazy]

Exploring the new Citation X, aren't we ?


SAT
Static air temperature (SAT), also referred to as outside air temperature (OAT). The temperature you would get in a forecast.

TAS
True Airspeed - speed realative to the air you're flying through.

GSPD
Ground speed - speed relative to the ground.

In easy terms: If you fly with a tail wind, TAS is relatively low compared to GSPD, with a head wind it's the opposite. That's why these values differ
most of the times.

And if you'd fly with 532 kts through a police radar, they'd certainly be irritated

[Drew]

yeah so much to learn, and the manual aint exactly in depth.

cheers for the explanation

[poden]

There's also IAS, Indicated Air Speed, which is pressure dependent. This is what the airspeed indicator in the cockpit actually displays. For a
given TAS, the IAS decreases with increasing altitude.

[Drew]

cheers for that

i wondered why i was having to do less IAS (and also why my overspeed limit was lower the higher i went) but doing a higher mach
speed


maybe i should get back in that Cessna and start the lessons again with Rod

[Mud]

Rod sucks he's always teminating my lessons

Mud

[SWAFO]

I like quizzes (or questions that sound like quizzes)!! lol.

Can anyone tell me what CAS means (it's a measurement of airspeed)?

[xvxmatthewxvx]

Climb Airspeed? How fast in KTS you are actually climbing?

[eazy]

Calibrated airspeed (CAS) is the speed theoretically shown by a simple airspeed indicator that is free from instrument error and position error.

A simple airspeed indicator has only one capsule measuring impact pressure (pitot - static differential). CAS must therefore be defined as a function
of impact pressure alone. The instrument does not "know" the absolute static pressure or the static air temperature. Static pressure
and temperature are therefore defined by convention as standard sea level values. [....]

The definition is based on a model of the air as a compressible fluid. CAS therefore represents true airspeed (TAS) at all subsonic speeds
under the reference conditions, i.e. standard sea level pressure and temperature.

At higher altitudes CAS must be corrected for compressibility error to give equivalent airspeed (EAS), and EAS must in turn be corrected for
density to give TAS. In practice compressibility error is negligible below about 10000 feet and 200 knots.

With the advent of the glass cockpit, even in small aircraft, the mechanical airspeed indicator may become obsolete, being replaced by an air
data computer. An air data computer which has inputs of static pressure and total air temperature as well as impact pressure can compute
EAS and TAS directly, as well as mach number, pressure altitude etc. CAS may also therefore become obsolete.
(Wikipedia)

I know, internet directories can be boring sometimes (when it comes to quizzes)