IAS to CAS

skyview_user

I love TopMeteo
Joined
Apr 4, 2016
Messages
58
Hi Dynon, is there a way to correct IAS to CAS? The wind and other computations are wrong if not....
Thanks for an answer.
 

GalinHdz

Active Member
Joined
Mar 3, 2008
Messages
716
Location
KSGJ/TJBQ
There is no way to "correct" IAS for CAS in the SkyView becasue, in a well designed system, IAS and CAS should be within a few knots of each other. An error like this normally indicates a problem with the location of your pitot/static system. The problem will show up as errors in speed, winds, altitude and other calculations. This has been discussed in multiple threads with the last one happening just a few days ago.

 
Last edited:

skyview_user

I love TopMeteo
Joined
Apr 4, 2016
Messages
58
Sorry. That was not my question. My system has no errors. I only want to have correct values.
 

GalinHdz

Active Member
Joined
Mar 3, 2008
Messages
716
Location
KSGJ/TJBQ
Sorry. That was not my question. My system has no errors. I only want to have correct values.
There is no IAS to CAS correction capability in SkyView, or any other name brand EFIS that I know of, because IAS and CAS should be within a few knots of each other. I hate to say this but it sounds like your system has a dynamic airflow error which makes wind, altitude and other calculations wrong. Not that uncommon with EAB aircraft. I had this same situation in my airplane.

:cool:
 
Last edited:

skyview_user

I love TopMeteo
Joined
Apr 4, 2016
Messages
58
hi dynon,
could you pls answer my question, i.e. given IAS, known CAS, how to enter the correction into SV? Thanks
 

RVDan

I love flying!
Joined
Aug 8, 2012
Messages
279
Location
Frederick, MD
If your pitot static system has no errors (not likely errors are 0) then, IAS=CAS. In a typical static system there will be < 3 kts error between the two, which in the scope of the wind calculations is small enough to be ignored. No EFIS that I am aware of allows the entry of CAS to correct IAS.
 

Raymo

I love aviation!
Joined
Apr 25, 2016
Messages
1,043
Location
Richmond Hill, GA
Why not use TAS, which the system already provides. In zero wind flight, TAS will match ground speed.
 

GalinHdz

Active Member
Joined
Mar 3, 2008
Messages
716
Location
KSGJ/TJBQ
In zero wind flight, TAS will match ground speed.
Not if the pitot/static system is providing the EFIS with a wrong IAS value. In a modern EFIS, TAS is calculated based on IAS, among other variables, so a wrong IAS will give a wrong TAS. "Garbage in, garbage out."
 
Last edited:
Top