Well I did the triangulate calculation using the spread sheet on this site to calculate the TAS on my recently flying 10. Now what do I do with that figure? What do I compare the results with to make this exercise useful?
The inputs are Groundspeed at 3 different headings, IAS, OAT, and Pressure Altitude. The spreadsheet tells you what your True Airspeed was, what your Indicated Airspeed should have been reading, and the error - ie IAS off the Airspeed Indicator was 150 knots, but it should have been 155, so you have a 5 knot error. It also calculates altitude error. It is then up to you to determine what is causing the error and how to fix it - in my experience it has always been in the static system.