4.09 - Support & Bug Reporting

[Blackdog_kt]

I'm not sure but my understanding is that Tempest is referring to the actual cockpit instruments and not discrepancies between cockpit (IAS) and no-cockpit (TAS) airspeed gauges.

Talking about cockpit gauges that display IAS, it's not rare to see airspeed indicators calibrated in a non-linear scale. So for example, there are tick marks every 20 degrees around the gauge's face for low speeds to provide more accurate readings/better scale resolution where it's possible to encounter a stall, but then the tick marks are placed every 10 degrees for the high speed range in order to save up on the amount of instrument space needed. If the same high resolution scale of 20 degrees per tick mark was used for the high speed range as well, we might need an airspeed gauge that functions in more than 360 degrees (like the ones found in the RAF aircraft for example). Shortening the distance between tick marks in the high speed range means that we can have instruments that display a bigger speed range without having to use a dual inner/outer speed read-out ring like the British indicators, just at the expense of reduced scale resolution at high speeds.

However, this means that the needle also has to move in a non linear way to ensure an accurate change over from one scale to the next.
If the needle's movement keeps linear when the scale of the gauge isn't, then the result is inaccurate readings at high speeds.

I could still be wrong, but that's the way i interpreted Tempest's post.