An interesting part mnemonic, part diagram that I learned in order to understand the changing relationships between LSS, RAS, TAS and Mach Number in the climb and descent under normal conditions and in temperature inversions. (One for the Bristol Mod 1 guys (Instruments)).
Start by drawing the X and Y axis of a graph, just 2 straight lines one vertical and another horizontal.
On this graph diagrammatically represent the path of a climbing aircraft by drawing a line from the origin moving upwards and to the right.
Think to yourself that looks right to me in the sense that the line looks like the path that an aircraft follows whilst climbing the key is in the order
LSS = Looks
RAS = Right
TAS = To
MN = Me
Draw 4 lines at equal intervals across the graph from top to bottom so that the climb line cuts through them all (Wish I could show you with a diagram) label the lines L,R,T and M.
You now have a diagram illustrating the relationships between the different values. If your climb line cuts across the L,R,T or M lines at points higher up than others this implies that the value increases in the climb and vice versa, so for example it can be seen quickly that in a climb at a fixed Mach Number the TAS will increase, whilst the RAS and the Local Speed of Sound will fall.
If the question asks about inversions then instead of thinking about the climb looking right to me think about what an inversion is A Right Mess of Temperature. L remains in the same position as the vertical line to the far left of the graph, whilst the other lines change their relative positions R M T.
The graph can then be used in the same way.
This may sound complicated but in fact the diagrams could not be simpler and take only perhaps 2 seconds to draw in an exam 1 or 2 marks virtually guaranteed in Instruments.
Another mnemonic which may help you to learn the different speeds and the various errors that are corrected between them all is Instrument Rating Examiners are Truly Picked.
Write out I R E T (Instrument Rating Examiners are Truly)
Then write just underneath picked spelt PICD, with the P and the I sitting between the I and the R above, the C sitting between the R and the E above and the D sitting between the E and the T above
You are probably one step ahead of me by now but if not the I R E T gives you IAS, RAS, EAS and TAS and the letters on the lower lines give the errors that are corrected to give rise to the speeds Pressure, Instrument, Compressibility and Density. Hence RAS is IAS corrected for pressure and instrument errors, whilst TAS is EAS corrected for density errors.
Hope these are of use to some of you.
Oopps
No sooner posted than spotted the deliberate mistake In an Inversion as you climb of course local temp increases and hence the LSS will increase. Best put the L line on the other end !