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Airspeed (Read 263 times)

Jun 14^th, 2004 at 3:31pm

afsoc Offline
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England

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hi guys, ok this is kinda related to fs and real life. Ok ive been trying to figure something out.

In real world civil flying do they use true air speed or indicated airspeed. The reason I ask is ive been looking at the a330 which states it has a cruise speed of around 450 + knots m.82 now the only way in flight sim you can get that is by using true airspeed not indicated.

I hope im making sence but if someone can explain between indicated and true id be grateful as i cant work out y have both?

please help

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Reply #1 - Jun 14^th, 2004 at 4:42pm

Felix/FFDS Offline
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https://ewhdbks.mugu.navy.mil/mach-as.htm

AIRSPEED is a term that can be easily confused. The unqualified term airspeed can mean any of the following:
a. Indicated airspeed (IAS) - the airspeed shown by an airspeed indicator in an aircraft. Indicated airspeed is expressed in
knots and is abbreviated KIAS.
b. Calibrated airspeed (CAS) - indicated airspeed corrected for static source error due to location of pickup sensor on
aircraft. Calibrated airspeed is expressed in knots and is abbreviated KCAS. Normally it doesn't differ much from IAS.
c. True airspeed (TAS) - IAS corrected for instrument installation error, compressibility error, and errors due to variations
from standard air density. TAS is expressed in knots and is abbreviated KTAS. TAS is approximately equal to CAS at
sea level but increases relative to CAS as altitude increases. At 35,000 ft, 250 KIAS (or KCAS) is approximately 430
KTAS.
IAS (or CAS) is important in that aircraft dynamics (such as stall speed) responds largely to this quantity. TAS is important
for use in navigation (True airspeed ± windspeed = groundspeed).

Felix/FFDS

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Reply #2 - Jun 14^th, 2004 at 10:55pm

OTTOL Offline
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Fintas, Kuwait (OKBK)

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Geez professor, I think you nailed him between the eyes with that manual!
If you don't mind me butting in Felix.......
Quote:

In real world civil flying do they use true air speed or indicated airspeed.

Both....... Indicated airspeed is used in real world flying, chiefly for the purpose of ATC queries and planning. In other words, when ATC asks "what's your airspeed", you give him the number on the airspeed indicator(IAS or MACH). TAS and Groundspeed are used for flight planning.
The "stated" 450kt speed that you mentioned is TAS. If your Airbus INDICATED 450, you would be exceeding MACH1! Shocked

.....so I loaded up the plane and moved to Middle-EEEE..........OIL..that is......

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Reply #3 - Jun 15^th, 2004 at 2:03pm

afsoc Offline
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we rule
England

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Posts: 57

thats what threw me but if you look at almost all airbus info regarding airspeed it states a cruise of 450/ m.82 Roll Eyes

owell ill stick to what i know IAS but seems to be one thing that is really tough to get your head around. O and thanks for the lamons turm all that tech info lost me even more.

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