View Full Version : indicated vs true airspeed

04-28-2007, 08:04 AM
How big is the difference between indicated and true airspeed? Can you give some examples? Thanks in advance

04-28-2007, 08:09 AM
Depends on the plane and altitude.

I remember seeing some charts around somewhere....

04-28-2007, 08:21 AM
It has nothing to do with the airplane.

It has everything to do with air density. Air density depends on moisture, altitude and temperature. The air is less dense at higher altitudes, therefore the difference between IAS and TAS is greater.

You could've found the same thing on Google.

04-28-2007, 08:32 AM
Here is a quote from your friend Wikipedia

In aneroid instruments the indicated airspeed drops-off with increasing altitude as air pressure decreases, and this leads to an apparent falling-off of airspeed at higher altitudes. For this reason Vne speeds are often given at several differing altitudes in the aircraft's operating manual, the Vne IAS figure falling as height is increased, as shown in the sample table below.

Diving below m.p.h IAS
30,000 ft 370
25,000 ft 410
20,000 ft 450
15,000 ft 490
10,000 ft 540

04-28-2007, 08:47 AM
Originally posted by LStarosta:

You could've found the same thing on Google.

Ease up homes, and holster the gat

04-28-2007, 01:23 PM
megile 4 Sherrif http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Metatron- you can try this link, and see for yourself how big a difference IAS vs TAS can be:


Leave the OAT at .02, it's a standard correction